Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
4 : *
5 : * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 : *
7 : * Interactivity improvements by Mike Galbraith
8 : * (C) 2007 Mike Galbraith <efault@gmx.de>
9 : *
10 : * Various enhancements by Dmitry Adamushko.
11 : * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
12 : *
13 : * Group scheduling enhancements by Srivatsa Vaddagiri
14 : * Copyright IBM Corporation, 2007
15 : * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
16 : *
17 : * Scaled math optimizations by Thomas Gleixner
18 : * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
19 : *
20 : * Adaptive scheduling granularity, math enhancements by Peter Zijlstra
21 : * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
22 : */
23 : #include <linux/energy_model.h>
24 : #include <linux/mmap_lock.h>
25 : #include <linux/hugetlb_inline.h>
26 : #include <linux/jiffies.h>
27 : #include <linux/mm_api.h>
28 : #include <linux/highmem.h>
29 : #include <linux/spinlock_api.h>
30 : #include <linux/cpumask_api.h>
31 : #include <linux/lockdep_api.h>
32 : #include <linux/softirq.h>
33 : #include <linux/refcount_api.h>
34 : #include <linux/topology.h>
35 : #include <linux/sched/clock.h>
36 : #include <linux/sched/cond_resched.h>
37 : #include <linux/sched/cputime.h>
38 : #include <linux/sched/isolation.h>
39 : #include <linux/sched/nohz.h>
40 :
41 : #include <linux/cpuidle.h>
42 : #include <linux/interrupt.h>
43 : #include <linux/memory-tiers.h>
44 : #include <linux/mempolicy.h>
45 : #include <linux/mutex_api.h>
46 : #include <linux/profile.h>
47 : #include <linux/psi.h>
48 : #include <linux/ratelimit.h>
49 : #include <linux/task_work.h>
50 :
51 : #include <asm/switch_to.h>
52 :
53 : #include <linux/sched/cond_resched.h>
54 :
55 : #include "sched.h"
56 : #include "stats.h"
57 : #include "autogroup.h"
58 :
59 : /*
60 : * Targeted preemption latency for CPU-bound tasks:
61 : *
62 : * NOTE: this latency value is not the same as the concept of
63 : * 'timeslice length' - timeslices in CFS are of variable length
64 : * and have no persistent notion like in traditional, time-slice
65 : * based scheduling concepts.
66 : *
67 : * (to see the precise effective timeslice length of your workload,
68 : * run vmstat and monitor the context-switches (cs) field)
69 : *
70 : * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
71 : */
72 : unsigned int sysctl_sched_latency = 6000000ULL;
73 : static unsigned int normalized_sysctl_sched_latency = 6000000ULL;
74 :
75 : /*
76 : * The initial- and re-scaling of tunables is configurable
77 : *
78 : * Options are:
79 : *
80 : * SCHED_TUNABLESCALING_NONE - unscaled, always *1
81 : * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
82 : * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
83 : *
84 : * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
85 : */
86 : unsigned int sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG;
87 :
88 : /*
89 : * Minimal preemption granularity for CPU-bound tasks:
90 : *
91 : * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
92 : */
93 : unsigned int sysctl_sched_min_granularity = 750000ULL;
94 : static unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
95 :
96 : /*
97 : * Minimal preemption granularity for CPU-bound SCHED_IDLE tasks.
98 : * Applies only when SCHED_IDLE tasks compete with normal tasks.
99 : *
100 : * (default: 0.75 msec)
101 : */
102 : unsigned int sysctl_sched_idle_min_granularity = 750000ULL;
103 :
104 : /*
105 : * This value is kept at sysctl_sched_latency/sysctl_sched_min_granularity
106 : */
107 : static unsigned int sched_nr_latency = 8;
108 :
109 : /*
110 : * After fork, child runs first. If set to 0 (default) then
111 : * parent will (try to) run first.
112 : */
113 : unsigned int sysctl_sched_child_runs_first __read_mostly;
114 :
115 : /*
116 : * SCHED_OTHER wake-up granularity.
117 : *
118 : * This option delays the preemption effects of decoupled workloads
119 : * and reduces their over-scheduling. Synchronous workloads will still
120 : * have immediate wakeup/sleep latencies.
121 : *
122 : * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
123 : */
124 : unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
125 : static unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
126 :
127 : const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
128 :
129 : int sched_thermal_decay_shift;
130 0 : static int __init setup_sched_thermal_decay_shift(char *str)
131 : {
132 0 : int _shift = 0;
133 :
134 0 : if (kstrtoint(str, 0, &_shift))
135 0 : pr_warn("Unable to set scheduler thermal pressure decay shift parameter\n");
136 :
137 0 : sched_thermal_decay_shift = clamp(_shift, 0, 10);
138 0 : return 1;
139 : }
140 : __setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift);
141 :
142 : #ifdef CONFIG_SMP
143 : /*
144 : * For asym packing, by default the lower numbered CPU has higher priority.
145 : */
146 : int __weak arch_asym_cpu_priority(int cpu)
147 : {
148 : return -cpu;
149 : }
150 :
151 : /*
152 : * The margin used when comparing utilization with CPU capacity.
153 : *
154 : * (default: ~20%)
155 : */
156 : #define fits_capacity(cap, max) ((cap) * 1280 < (max) * 1024)
157 :
158 : /*
159 : * The margin used when comparing CPU capacities.
160 : * is 'cap1' noticeably greater than 'cap2'
161 : *
162 : * (default: ~5%)
163 : */
164 : #define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
165 : #endif
166 :
167 : #ifdef CONFIG_CFS_BANDWIDTH
168 : /*
169 : * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
170 : * each time a cfs_rq requests quota.
171 : *
172 : * Note: in the case that the slice exceeds the runtime remaining (either due
173 : * to consumption or the quota being specified to be smaller than the slice)
174 : * we will always only issue the remaining available time.
175 : *
176 : * (default: 5 msec, units: microseconds)
177 : */
178 : static unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
179 : #endif
180 :
181 : #ifdef CONFIG_NUMA_BALANCING
182 : /* Restrict the NUMA promotion throughput (MB/s) for each target node. */
183 : static unsigned int sysctl_numa_balancing_promote_rate_limit = 65536;
184 : #endif
185 :
186 : #ifdef CONFIG_SYSCTL
187 : static struct ctl_table sched_fair_sysctls[] = {
188 : {
189 : .procname = "sched_child_runs_first",
190 : .data = &sysctl_sched_child_runs_first,
191 : .maxlen = sizeof(unsigned int),
192 : .mode = 0644,
193 : .proc_handler = proc_dointvec,
194 : },
195 : #ifdef CONFIG_CFS_BANDWIDTH
196 : {
197 : .procname = "sched_cfs_bandwidth_slice_us",
198 : .data = &sysctl_sched_cfs_bandwidth_slice,
199 : .maxlen = sizeof(unsigned int),
200 : .mode = 0644,
201 : .proc_handler = proc_dointvec_minmax,
202 : .extra1 = SYSCTL_ONE,
203 : },
204 : #endif
205 : #ifdef CONFIG_NUMA_BALANCING
206 : {
207 : .procname = "numa_balancing_promote_rate_limit_MBps",
208 : .data = &sysctl_numa_balancing_promote_rate_limit,
209 : .maxlen = sizeof(unsigned int),
210 : .mode = 0644,
211 : .proc_handler = proc_dointvec_minmax,
212 : .extra1 = SYSCTL_ZERO,
213 : },
214 : #endif /* CONFIG_NUMA_BALANCING */
215 : {}
216 : };
217 :
218 1 : static int __init sched_fair_sysctl_init(void)
219 : {
220 1 : register_sysctl_init("kernel", sched_fair_sysctls);
221 1 : return 0;
222 : }
223 : late_initcall(sched_fair_sysctl_init);
224 : #endif
225 :
226 : static inline void update_load_add(struct load_weight *lw, unsigned long inc)
227 : {
228 1210 : lw->weight += inc;
229 1210 : lw->inv_weight = 0;
230 : }
231 :
232 : static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
233 : {
234 1033 : lw->weight -= dec;
235 1033 : lw->inv_weight = 0;
236 : }
237 :
238 : static inline void update_load_set(struct load_weight *lw, unsigned long w)
239 : {
240 5 : lw->weight = w;
241 5 : lw->inv_weight = 0;
242 : }
243 :
244 : /*
245 : * Increase the granularity value when there are more CPUs,
246 : * because with more CPUs the 'effective latency' as visible
247 : * to users decreases. But the relationship is not linear,
248 : * so pick a second-best guess by going with the log2 of the
249 : * number of CPUs.
250 : *
251 : * This idea comes from the SD scheduler of Con Kolivas:
252 : */
253 : static unsigned int get_update_sysctl_factor(void)
254 : {
255 1 : unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8);
256 : unsigned int factor;
257 :
258 : switch (sysctl_sched_tunable_scaling) {
259 : case SCHED_TUNABLESCALING_NONE:
260 : factor = 1;
261 : break;
262 : case SCHED_TUNABLESCALING_LINEAR:
263 : factor = cpus;
264 : break;
265 : case SCHED_TUNABLESCALING_LOG:
266 : default:
267 : factor = 1 + ilog2(cpus);
268 : break;
269 : }
270 :
271 : return factor;
272 : }
273 :
274 : static void update_sysctl(void)
275 : {
276 1 : unsigned int factor = get_update_sysctl_factor();
277 :
278 : #define SET_SYSCTL(name) \
279 : (sysctl_##name = (factor) * normalized_sysctl_##name)
280 1 : SET_SYSCTL(sched_min_granularity);
281 1 : SET_SYSCTL(sched_latency);
282 1 : SET_SYSCTL(sched_wakeup_granularity);
283 : #undef SET_SYSCTL
284 : }
285 :
286 1 : void __init sched_init_granularity(void)
287 : {
288 : update_sysctl();
289 1 : }
290 :
291 : #define WMULT_CONST (~0U)
292 : #define WMULT_SHIFT 32
293 :
294 : static void __update_inv_weight(struct load_weight *lw)
295 : {
296 : unsigned long w;
297 :
298 176 : if (likely(lw->inv_weight))
299 : return;
300 :
301 176 : w = scale_load_down(lw->weight);
302 :
303 176 : if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
304 0 : lw->inv_weight = 1;
305 176 : else if (unlikely(!w))
306 0 : lw->inv_weight = WMULT_CONST;
307 : else
308 176 : lw->inv_weight = WMULT_CONST / w;
309 : }
310 :
311 : /*
312 : * delta_exec * weight / lw.weight
313 : * OR
314 : * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT
315 : *
316 : * Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case
317 : * we're guaranteed shift stays positive because inv_weight is guaranteed to
318 : * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22.
319 : *
320 : * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus
321 : * weight/lw.weight <= 1, and therefore our shift will also be positive.
322 : */
323 176 : static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw)
324 : {
325 176 : u64 fact = scale_load_down(weight);
326 176 : u32 fact_hi = (u32)(fact >> 32);
327 176 : int shift = WMULT_SHIFT;
328 : int fs;
329 :
330 176 : __update_inv_weight(lw);
331 :
332 176 : if (unlikely(fact_hi)) {
333 0 : fs = fls(fact_hi);
334 0 : shift -= fs;
335 0 : fact >>= fs;
336 : }
337 :
338 352 : fact = mul_u32_u32(fact, lw->inv_weight);
339 :
340 176 : fact_hi = (u32)(fact >> 32);
341 176 : if (fact_hi) {
342 0 : fs = fls(fact_hi);
343 0 : shift -= fs;
344 0 : fact >>= fs;
345 : }
346 :
347 352 : return mul_u64_u32_shr(delta_exec, fact, shift);
348 : }
349 :
350 :
351 : const struct sched_class fair_sched_class;
352 :
353 : /**************************************************************
354 : * CFS operations on generic schedulable entities:
355 : */
356 :
357 : #ifdef CONFIG_FAIR_GROUP_SCHED
358 :
359 : /* Walk up scheduling entities hierarchy */
360 : #define for_each_sched_entity(se) \
361 : for (; se; se = se->parent)
362 :
363 : static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
364 : {
365 : struct rq *rq = rq_of(cfs_rq);
366 : int cpu = cpu_of(rq);
367 :
368 : if (cfs_rq->on_list)
369 : return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list;
370 :
371 : cfs_rq->on_list = 1;
372 :
373 : /*
374 : * Ensure we either appear before our parent (if already
375 : * enqueued) or force our parent to appear after us when it is
376 : * enqueued. The fact that we always enqueue bottom-up
377 : * reduces this to two cases and a special case for the root
378 : * cfs_rq. Furthermore, it also means that we will always reset
379 : * tmp_alone_branch either when the branch is connected
380 : * to a tree or when we reach the top of the tree
381 : */
382 : if (cfs_rq->tg->parent &&
383 : cfs_rq->tg->parent->cfs_rq[cpu]->on_list) {
384 : /*
385 : * If parent is already on the list, we add the child
386 : * just before. Thanks to circular linked property of
387 : * the list, this means to put the child at the tail
388 : * of the list that starts by parent.
389 : */
390 : list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
391 : &(cfs_rq->tg->parent->cfs_rq[cpu]->leaf_cfs_rq_list));
392 : /*
393 : * The branch is now connected to its tree so we can
394 : * reset tmp_alone_branch to the beginning of the
395 : * list.
396 : */
397 : rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
398 : return true;
399 : }
400 :
401 : if (!cfs_rq->tg->parent) {
402 : /*
403 : * cfs rq without parent should be put
404 : * at the tail of the list.
405 : */
406 : list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
407 : &rq->leaf_cfs_rq_list);
408 : /*
409 : * We have reach the top of a tree so we can reset
410 : * tmp_alone_branch to the beginning of the list.
411 : */
412 : rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
413 : return true;
414 : }
415 :
416 : /*
417 : * The parent has not already been added so we want to
418 : * make sure that it will be put after us.
419 : * tmp_alone_branch points to the begin of the branch
420 : * where we will add parent.
421 : */
422 : list_add_rcu(&cfs_rq->leaf_cfs_rq_list, rq->tmp_alone_branch);
423 : /*
424 : * update tmp_alone_branch to points to the new begin
425 : * of the branch
426 : */
427 : rq->tmp_alone_branch = &cfs_rq->leaf_cfs_rq_list;
428 : return false;
429 : }
430 :
431 : static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
432 : {
433 : if (cfs_rq->on_list) {
434 : struct rq *rq = rq_of(cfs_rq);
435 :
436 : /*
437 : * With cfs_rq being unthrottled/throttled during an enqueue,
438 : * it can happen the tmp_alone_branch points the a leaf that
439 : * we finally want to del. In this case, tmp_alone_branch moves
440 : * to the prev element but it will point to rq->leaf_cfs_rq_list
441 : * at the end of the enqueue.
442 : */
443 : if (rq->tmp_alone_branch == &cfs_rq->leaf_cfs_rq_list)
444 : rq->tmp_alone_branch = cfs_rq->leaf_cfs_rq_list.prev;
445 :
446 : list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
447 : cfs_rq->on_list = 0;
448 : }
449 : }
450 :
451 : static inline void assert_list_leaf_cfs_rq(struct rq *rq)
452 : {
453 : SCHED_WARN_ON(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list);
454 : }
455 :
456 : /* Iterate thr' all leaf cfs_rq's on a runqueue */
457 : #define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \
458 : list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list, \
459 : leaf_cfs_rq_list)
460 :
461 : /* Do the two (enqueued) entities belong to the same group ? */
462 : static inline struct cfs_rq *
463 : is_same_group(struct sched_entity *se, struct sched_entity *pse)
464 : {
465 : if (se->cfs_rq == pse->cfs_rq)
466 : return se->cfs_rq;
467 :
468 : return NULL;
469 : }
470 :
471 : static inline struct sched_entity *parent_entity(const struct sched_entity *se)
472 : {
473 : return se->parent;
474 : }
475 :
476 : static void
477 : find_matching_se(struct sched_entity **se, struct sched_entity **pse)
478 : {
479 : int se_depth, pse_depth;
480 :
481 : /*
482 : * preemption test can be made between sibling entities who are in the
483 : * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
484 : * both tasks until we find their ancestors who are siblings of common
485 : * parent.
486 : */
487 :
488 : /* First walk up until both entities are at same depth */
489 : se_depth = (*se)->depth;
490 : pse_depth = (*pse)->depth;
491 :
492 : while (se_depth > pse_depth) {
493 : se_depth--;
494 : *se = parent_entity(*se);
495 : }
496 :
497 : while (pse_depth > se_depth) {
498 : pse_depth--;
499 : *pse = parent_entity(*pse);
500 : }
501 :
502 : while (!is_same_group(*se, *pse)) {
503 : *se = parent_entity(*se);
504 : *pse = parent_entity(*pse);
505 : }
506 : }
507 :
508 : static int tg_is_idle(struct task_group *tg)
509 : {
510 : return tg->idle > 0;
511 : }
512 :
513 : static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
514 : {
515 : return cfs_rq->idle > 0;
516 : }
517 :
518 : static int se_is_idle(struct sched_entity *se)
519 : {
520 : if (entity_is_task(se))
521 : return task_has_idle_policy(task_of(se));
522 : return cfs_rq_is_idle(group_cfs_rq(se));
523 : }
524 :
525 : #else /* !CONFIG_FAIR_GROUP_SCHED */
526 :
527 : #define for_each_sched_entity(se) \
528 : for (; se; se = NULL)
529 :
530 : static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
531 : {
532 : return true;
533 : }
534 :
535 : static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
536 : {
537 : }
538 :
539 : static inline void assert_list_leaf_cfs_rq(struct rq *rq)
540 : {
541 : }
542 :
543 : #define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) \
544 : for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = pos)
545 :
546 : static inline struct sched_entity *parent_entity(struct sched_entity *se)
547 : {
548 : return NULL;
549 : }
550 :
551 : static inline void
552 : find_matching_se(struct sched_entity **se, struct sched_entity **pse)
553 : {
554 : }
555 :
556 : static inline int tg_is_idle(struct task_group *tg)
557 : {
558 : return 0;
559 : }
560 :
561 : static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
562 : {
563 : return 0;
564 : }
565 :
566 : static int se_is_idle(struct sched_entity *se)
567 : {
568 : return 0;
569 : }
570 :
571 : #endif /* CONFIG_FAIR_GROUP_SCHED */
572 :
573 : static __always_inline
574 : void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec);
575 :
576 : /**************************************************************
577 : * Scheduling class tree data structure manipulation methods:
578 : */
579 :
580 : static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
581 : {
582 2061 : s64 delta = (s64)(vruntime - max_vruntime);
583 2061 : if (delta > 0)
584 864 : max_vruntime = vruntime;
585 :
586 : return max_vruntime;
587 : }
588 :
589 : static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
590 : {
591 1 : s64 delta = (s64)(vruntime - min_vruntime);
592 1 : if (delta < 0)
593 1 : min_vruntime = vruntime;
594 :
595 : return min_vruntime;
596 : }
597 :
598 : static inline bool entity_before(const struct sched_entity *a,
599 : const struct sched_entity *b)
600 : {
601 377 : return (s64)(a->vruntime - b->vruntime) < 0;
602 : }
603 :
604 : #define __node_2_se(node) \
605 : rb_entry((node), struct sched_entity, run_node)
606 :
607 1030 : static void update_min_vruntime(struct cfs_rq *cfs_rq)
608 : {
609 1030 : struct sched_entity *curr = cfs_rq->curr;
610 1030 : struct rb_node *leftmost = rb_first_cached(&cfs_rq->tasks_timeline);
611 :
612 1030 : u64 vruntime = cfs_rq->min_vruntime;
613 :
614 1030 : if (curr) {
615 1030 : if (curr->on_rq)
616 1 : vruntime = curr->vruntime;
617 : else
618 : curr = NULL;
619 : }
620 :
621 1030 : if (leftmost) { /* non-empty tree */
622 1029 : struct sched_entity *se = __node_2_se(leftmost);
623 :
624 1029 : if (!curr)
625 1028 : vruntime = se->vruntime;
626 : else
627 1 : vruntime = min_vruntime(vruntime, se->vruntime);
628 : }
629 :
630 : /* ensure we never gain time by being placed backwards. */
631 2060 : u64_u32_store(cfs_rq->min_vruntime,
632 : max_vruntime(cfs_rq->min_vruntime, vruntime));
633 1030 : }
634 :
635 : static inline bool __entity_less(struct rb_node *a, const struct rb_node *b)
636 : {
637 377 : return entity_before(__node_2_se(a), __node_2_se(b));
638 : }
639 :
640 : /*
641 : * Enqueue an entity into the rb-tree:
642 : */
643 1035 : static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
644 : {
645 2070 : rb_add_cached(&se->run_node, &cfs_rq->tasks_timeline, __entity_less);
646 1035 : }
647 :
648 : static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
649 : {
650 1034 : rb_erase_cached(&se->run_node, &cfs_rq->tasks_timeline);
651 : }
652 :
653 0 : struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
654 : {
655 1030 : struct rb_node *left = rb_first_cached(&cfs_rq->tasks_timeline);
656 :
657 1030 : if (!left)
658 : return NULL;
659 :
660 1030 : return __node_2_se(left);
661 : }
662 :
663 : static struct sched_entity *__pick_next_entity(struct sched_entity *se)
664 : {
665 0 : struct rb_node *next = rb_next(&se->run_node);
666 :
667 0 : if (!next)
668 : return NULL;
669 :
670 0 : return __node_2_se(next);
671 : }
672 :
673 : #ifdef CONFIG_SCHED_DEBUG
674 : struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
675 : {
676 : struct rb_node *last = rb_last(&cfs_rq->tasks_timeline.rb_root);
677 :
678 : if (!last)
679 : return NULL;
680 :
681 : return __node_2_se(last);
682 : }
683 :
684 : /**************************************************************
685 : * Scheduling class statistics methods:
686 : */
687 :
688 : int sched_update_scaling(void)
689 : {
690 : unsigned int factor = get_update_sysctl_factor();
691 :
692 : sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
693 : sysctl_sched_min_granularity);
694 :
695 : #define WRT_SYSCTL(name) \
696 : (normalized_sysctl_##name = sysctl_##name / (factor))
697 : WRT_SYSCTL(sched_min_granularity);
698 : WRT_SYSCTL(sched_latency);
699 : WRT_SYSCTL(sched_wakeup_granularity);
700 : #undef WRT_SYSCTL
701 :
702 : return 0;
703 : }
704 : #endif
705 :
706 : /*
707 : * delta /= w
708 : */
709 : static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se)
710 : {
711 514 : if (unlikely(se->load.weight != NICE_0_LOAD))
712 0 : delta = __calc_delta(delta, NICE_0_LOAD, &se->load);
713 :
714 : return delta;
715 : }
716 :
717 : /*
718 : * The idea is to set a period in which each task runs once.
719 : *
720 : * When there are too many tasks (sched_nr_latency) we have to stretch
721 : * this period because otherwise the slices get too small.
722 : *
723 : * p = (nr <= nl) ? l : l*nr/nl
724 : */
725 : static u64 __sched_period(unsigned long nr_running)
726 : {
727 176 : if (unlikely(nr_running > sched_nr_latency))
728 0 : return nr_running * sysctl_sched_min_granularity;
729 : else
730 176 : return sysctl_sched_latency;
731 : }
732 :
733 : static bool sched_idle_cfs_rq(struct cfs_rq *cfs_rq);
734 :
735 : /*
736 : * We calculate the wall-time slice from the period by taking a part
737 : * proportional to the weight.
738 : *
739 : * s = p*P[w/rw]
740 : */
741 176 : static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
742 : {
743 176 : unsigned int nr_running = cfs_rq->nr_running;
744 176 : struct sched_entity *init_se = se;
745 : unsigned int min_gran;
746 : u64 slice;
747 :
748 : if (sched_feat(ALT_PERIOD))
749 176 : nr_running = rq_of(cfs_rq)->cfs.h_nr_running;
750 :
751 176 : slice = __sched_period(nr_running + !se->on_rq);
752 :
753 176 : for_each_sched_entity(se) {
754 : struct load_weight *load;
755 : struct load_weight lw;
756 : struct cfs_rq *qcfs_rq;
757 :
758 352 : qcfs_rq = cfs_rq_of(se);
759 176 : load = &qcfs_rq->load;
760 :
761 176 : if (unlikely(!se->on_rq)) {
762 175 : lw = qcfs_rq->load;
763 :
764 350 : update_load_add(&lw, se->load.weight);
765 175 : load = &lw;
766 : }
767 176 : slice = __calc_delta(slice, se->load.weight, load);
768 : }
769 :
770 : if (sched_feat(BASE_SLICE)) {
771 176 : if (se_is_idle(init_se) && !sched_idle_cfs_rq(cfs_rq))
772 : min_gran = sysctl_sched_idle_min_granularity;
773 : else
774 176 : min_gran = sysctl_sched_min_granularity;
775 :
776 176 : slice = max_t(u64, slice, min_gran);
777 : }
778 :
779 176 : return slice;
780 : }
781 :
782 : /*
783 : * We calculate the vruntime slice of a to-be-inserted task.
784 : *
785 : * vs = s/w
786 : */
787 175 : static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
788 : {
789 350 : return calc_delta_fair(sched_slice(cfs_rq, se), se);
790 : }
791 :
792 : #include "pelt.h"
793 : #ifdef CONFIG_SMP
794 :
795 : static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
796 : static unsigned long task_h_load(struct task_struct *p);
797 : static unsigned long capacity_of(int cpu);
798 :
799 : /* Give new sched_entity start runnable values to heavy its load in infant time */
800 : void init_entity_runnable_average(struct sched_entity *se)
801 : {
802 : struct sched_avg *sa = &se->avg;
803 :
804 : memset(sa, 0, sizeof(*sa));
805 :
806 : /*
807 : * Tasks are initialized with full load to be seen as heavy tasks until
808 : * they get a chance to stabilize to their real load level.
809 : * Group entities are initialized with zero load to reflect the fact that
810 : * nothing has been attached to the task group yet.
811 : */
812 : if (entity_is_task(se))
813 : sa->load_avg = scale_load_down(se->load.weight);
814 :
815 : /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
816 : }
817 :
818 : /*
819 : * With new tasks being created, their initial util_avgs are extrapolated
820 : * based on the cfs_rq's current util_avg:
821 : *
822 : * util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight
823 : *
824 : * However, in many cases, the above util_avg does not give a desired
825 : * value. Moreover, the sum of the util_avgs may be divergent, such
826 : * as when the series is a harmonic series.
827 : *
828 : * To solve this problem, we also cap the util_avg of successive tasks to
829 : * only 1/2 of the left utilization budget:
830 : *
831 : * util_avg_cap = (cpu_scale - cfs_rq->avg.util_avg) / 2^n
832 : *
833 : * where n denotes the nth task and cpu_scale the CPU capacity.
834 : *
835 : * For example, for a CPU with 1024 of capacity, a simplest series from
836 : * the beginning would be like:
837 : *
838 : * task util_avg: 512, 256, 128, 64, 32, 16, 8, ...
839 : * cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ...
840 : *
841 : * Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap)
842 : * if util_avg > util_avg_cap.
843 : */
844 : void post_init_entity_util_avg(struct task_struct *p)
845 : {
846 : struct sched_entity *se = &p->se;
847 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
848 : struct sched_avg *sa = &se->avg;
849 : long cpu_scale = arch_scale_cpu_capacity(cpu_of(rq_of(cfs_rq)));
850 : long cap = (long)(cpu_scale - cfs_rq->avg.util_avg) / 2;
851 :
852 : if (p->sched_class != &fair_sched_class) {
853 : /*
854 : * For !fair tasks do:
855 : *
856 : update_cfs_rq_load_avg(now, cfs_rq);
857 : attach_entity_load_avg(cfs_rq, se);
858 : switched_from_fair(rq, p);
859 : *
860 : * such that the next switched_to_fair() has the
861 : * expected state.
862 : */
863 : se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq);
864 : return;
865 : }
866 :
867 : if (cap > 0) {
868 : if (cfs_rq->avg.util_avg != 0) {
869 : sa->util_avg = cfs_rq->avg.util_avg * se->load.weight;
870 : sa->util_avg /= (cfs_rq->avg.load_avg + 1);
871 :
872 : if (sa->util_avg > cap)
873 : sa->util_avg = cap;
874 : } else {
875 : sa->util_avg = cap;
876 : }
877 : }
878 :
879 : sa->runnable_avg = sa->util_avg;
880 : }
881 :
882 : #else /* !CONFIG_SMP */
883 175 : void init_entity_runnable_average(struct sched_entity *se)
884 : {
885 175 : }
886 175 : void post_init_entity_util_avg(struct task_struct *p)
887 : {
888 175 : }
889 : static void update_tg_load_avg(struct cfs_rq *cfs_rq)
890 : {
891 : }
892 : #endif /* CONFIG_SMP */
893 :
894 : /*
895 : * Update the current task's runtime statistics.
896 : */
897 3104 : static void update_curr(struct cfs_rq *cfs_rq)
898 : {
899 3104 : struct sched_entity *curr = cfs_rq->curr;
900 6208 : u64 now = rq_clock_task(rq_of(cfs_rq));
901 : u64 delta_exec;
902 :
903 3104 : if (unlikely(!curr))
904 : return;
905 :
906 3097 : delta_exec = now - curr->exec_start;
907 3097 : if (unlikely((s64)delta_exec <= 0))
908 : return;
909 :
910 1 : curr->exec_start = now;
911 :
912 : if (schedstat_enabled()) {
913 : struct sched_statistics *stats;
914 :
915 : stats = __schedstats_from_se(curr);
916 : __schedstat_set(stats->exec_max,
917 : max(delta_exec, stats->exec_max));
918 : }
919 :
920 1 : curr->sum_exec_runtime += delta_exec;
921 : schedstat_add(cfs_rq->exec_clock, delta_exec);
922 :
923 1 : curr->vruntime += calc_delta_fair(delta_exec, curr);
924 1 : update_min_vruntime(cfs_rq);
925 :
926 : if (entity_is_task(curr)) {
927 1 : struct task_struct *curtask = task_of(curr);
928 :
929 1 : trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
930 1 : cgroup_account_cputime(curtask, delta_exec);
931 : account_group_exec_runtime(curtask, delta_exec);
932 : }
933 :
934 : account_cfs_rq_runtime(cfs_rq, delta_exec);
935 : }
936 :
937 0 : static void update_curr_fair(struct rq *rq)
938 : {
939 0 : update_curr(cfs_rq_of(&rq->curr->se));
940 0 : }
941 :
942 : static inline void
943 : update_stats_wait_start_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
944 : {
945 : struct sched_statistics *stats;
946 0 : struct task_struct *p = NULL;
947 :
948 : if (!schedstat_enabled())
949 : return;
950 :
951 : stats = __schedstats_from_se(se);
952 :
953 : if (entity_is_task(se))
954 : p = task_of(se);
955 :
956 : __update_stats_wait_start(rq_of(cfs_rq), p, stats);
957 : }
958 :
959 : static inline void
960 : update_stats_wait_end_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
961 : {
962 : struct sched_statistics *stats;
963 1034 : struct task_struct *p = NULL;
964 :
965 : if (!schedstat_enabled())
966 : return;
967 :
968 : stats = __schedstats_from_se(se);
969 :
970 : /*
971 : * When the sched_schedstat changes from 0 to 1, some sched se
972 : * maybe already in the runqueue, the se->statistics.wait_start
973 : * will be 0.So it will let the delta wrong. We need to avoid this
974 : * scenario.
975 : */
976 : if (unlikely(!schedstat_val(stats->wait_start)))
977 : return;
978 :
979 : if (entity_is_task(se))
980 : p = task_of(se);
981 :
982 : __update_stats_wait_end(rq_of(cfs_rq), p, stats);
983 : }
984 :
985 : static inline void
986 : update_stats_enqueue_sleeper_fair(struct cfs_rq *cfs_rq, struct sched_entity *se)
987 : {
988 : struct sched_statistics *stats;
989 : struct task_struct *tsk = NULL;
990 :
991 : if (!schedstat_enabled())
992 : return;
993 :
994 : stats = __schedstats_from_se(se);
995 :
996 : if (entity_is_task(se))
997 : tsk = task_of(se);
998 :
999 : __update_stats_enqueue_sleeper(rq_of(cfs_rq), tsk, stats);
1000 : }
1001 :
1002 : /*
1003 : * Task is being enqueued - update stats:
1004 : */
1005 : static inline void
1006 : update_stats_enqueue_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1007 : {
1008 : if (!schedstat_enabled())
1009 : return;
1010 :
1011 : /*
1012 : * Are we enqueueing a waiting task? (for current tasks
1013 : * a dequeue/enqueue event is a NOP)
1014 : */
1015 : if (se != cfs_rq->curr)
1016 : update_stats_wait_start_fair(cfs_rq, se);
1017 :
1018 : if (flags & ENQUEUE_WAKEUP)
1019 : update_stats_enqueue_sleeper_fair(cfs_rq, se);
1020 : }
1021 :
1022 : static inline void
1023 : update_stats_dequeue_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1024 : {
1025 :
1026 : if (!schedstat_enabled())
1027 : return;
1028 :
1029 : /*
1030 : * Mark the end of the wait period if dequeueing a
1031 : * waiting task:
1032 : */
1033 : if (se != cfs_rq->curr)
1034 : update_stats_wait_end_fair(cfs_rq, se);
1035 :
1036 : if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) {
1037 : struct task_struct *tsk = task_of(se);
1038 : unsigned int state;
1039 :
1040 : /* XXX racy against TTWU */
1041 : state = READ_ONCE(tsk->__state);
1042 : if (state & TASK_INTERRUPTIBLE)
1043 : __schedstat_set(tsk->stats.sleep_start,
1044 : rq_clock(rq_of(cfs_rq)));
1045 : if (state & TASK_UNINTERRUPTIBLE)
1046 : __schedstat_set(tsk->stats.block_start,
1047 : rq_clock(rq_of(cfs_rq)));
1048 : }
1049 : }
1050 :
1051 : /*
1052 : * We are picking a new current task - update its stats:
1053 : */
1054 : static inline void
1055 : update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
1056 : {
1057 : /*
1058 : * We are starting a new run period:
1059 : */
1060 2068 : se->exec_start = rq_clock_task(rq_of(cfs_rq));
1061 : }
1062 :
1063 : /**************************************************
1064 : * Scheduling class queueing methods:
1065 : */
1066 :
1067 : static inline bool is_core_idle(int cpu)
1068 : {
1069 : #ifdef CONFIG_SCHED_SMT
1070 : int sibling;
1071 :
1072 : for_each_cpu(sibling, cpu_smt_mask(cpu)) {
1073 : if (cpu == sibling)
1074 : continue;
1075 :
1076 : if (!idle_cpu(sibling))
1077 : return false;
1078 : }
1079 : #endif
1080 :
1081 : return true;
1082 : }
1083 :
1084 : #ifdef CONFIG_NUMA
1085 : #define NUMA_IMBALANCE_MIN 2
1086 :
1087 : static inline long
1088 : adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
1089 : {
1090 : /*
1091 : * Allow a NUMA imbalance if busy CPUs is less than the maximum
1092 : * threshold. Above this threshold, individual tasks may be contending
1093 : * for both memory bandwidth and any shared HT resources. This is an
1094 : * approximation as the number of running tasks may not be related to
1095 : * the number of busy CPUs due to sched_setaffinity.
1096 : */
1097 : if (dst_running > imb_numa_nr)
1098 : return imbalance;
1099 :
1100 : /*
1101 : * Allow a small imbalance based on a simple pair of communicating
1102 : * tasks that remain local when the destination is lightly loaded.
1103 : */
1104 : if (imbalance <= NUMA_IMBALANCE_MIN)
1105 : return 0;
1106 :
1107 : return imbalance;
1108 : }
1109 : #endif /* CONFIG_NUMA */
1110 :
1111 : #ifdef CONFIG_NUMA_BALANCING
1112 : /*
1113 : * Approximate time to scan a full NUMA task in ms. The task scan period is
1114 : * calculated based on the tasks virtual memory size and
1115 : * numa_balancing_scan_size.
1116 : */
1117 : unsigned int sysctl_numa_balancing_scan_period_min = 1000;
1118 : unsigned int sysctl_numa_balancing_scan_period_max = 60000;
1119 :
1120 : /* Portion of address space to scan in MB */
1121 : unsigned int sysctl_numa_balancing_scan_size = 256;
1122 :
1123 : /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
1124 : unsigned int sysctl_numa_balancing_scan_delay = 1000;
1125 :
1126 : /* The page with hint page fault latency < threshold in ms is considered hot */
1127 : unsigned int sysctl_numa_balancing_hot_threshold = MSEC_PER_SEC;
1128 :
1129 : struct numa_group {
1130 : refcount_t refcount;
1131 :
1132 : spinlock_t lock; /* nr_tasks, tasks */
1133 : int nr_tasks;
1134 : pid_t gid;
1135 : int active_nodes;
1136 :
1137 : struct rcu_head rcu;
1138 : unsigned long total_faults;
1139 : unsigned long max_faults_cpu;
1140 : /*
1141 : * faults[] array is split into two regions: faults_mem and faults_cpu.
1142 : *
1143 : * Faults_cpu is used to decide whether memory should move
1144 : * towards the CPU. As a consequence, these stats are weighted
1145 : * more by CPU use than by memory faults.
1146 : */
1147 : unsigned long faults[];
1148 : };
1149 :
1150 : /*
1151 : * For functions that can be called in multiple contexts that permit reading
1152 : * ->numa_group (see struct task_struct for locking rules).
1153 : */
1154 : static struct numa_group *deref_task_numa_group(struct task_struct *p)
1155 : {
1156 : return rcu_dereference_check(p->numa_group, p == current ||
1157 : (lockdep_is_held(__rq_lockp(task_rq(p))) && !READ_ONCE(p->on_cpu)));
1158 : }
1159 :
1160 : static struct numa_group *deref_curr_numa_group(struct task_struct *p)
1161 : {
1162 : return rcu_dereference_protected(p->numa_group, p == current);
1163 : }
1164 :
1165 : static inline unsigned long group_faults_priv(struct numa_group *ng);
1166 : static inline unsigned long group_faults_shared(struct numa_group *ng);
1167 :
1168 : static unsigned int task_nr_scan_windows(struct task_struct *p)
1169 : {
1170 : unsigned long rss = 0;
1171 : unsigned long nr_scan_pages;
1172 :
1173 : /*
1174 : * Calculations based on RSS as non-present and empty pages are skipped
1175 : * by the PTE scanner and NUMA hinting faults should be trapped based
1176 : * on resident pages
1177 : */
1178 : nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT);
1179 : rss = get_mm_rss(p->mm);
1180 : if (!rss)
1181 : rss = nr_scan_pages;
1182 :
1183 : rss = round_up(rss, nr_scan_pages);
1184 : return rss / nr_scan_pages;
1185 : }
1186 :
1187 : /* For sanity's sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */
1188 : #define MAX_SCAN_WINDOW 2560
1189 :
1190 : static unsigned int task_scan_min(struct task_struct *p)
1191 : {
1192 : unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size);
1193 : unsigned int scan, floor;
1194 : unsigned int windows = 1;
1195 :
1196 : if (scan_size < MAX_SCAN_WINDOW)
1197 : windows = MAX_SCAN_WINDOW / scan_size;
1198 : floor = 1000 / windows;
1199 :
1200 : scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p);
1201 : return max_t(unsigned int, floor, scan);
1202 : }
1203 :
1204 : static unsigned int task_scan_start(struct task_struct *p)
1205 : {
1206 : unsigned long smin = task_scan_min(p);
1207 : unsigned long period = smin;
1208 : struct numa_group *ng;
1209 :
1210 : /* Scale the maximum scan period with the amount of shared memory. */
1211 : rcu_read_lock();
1212 : ng = rcu_dereference(p->numa_group);
1213 : if (ng) {
1214 : unsigned long shared = group_faults_shared(ng);
1215 : unsigned long private = group_faults_priv(ng);
1216 :
1217 : period *= refcount_read(&ng->refcount);
1218 : period *= shared + 1;
1219 : period /= private + shared + 1;
1220 : }
1221 : rcu_read_unlock();
1222 :
1223 : return max(smin, period);
1224 : }
1225 :
1226 : static unsigned int task_scan_max(struct task_struct *p)
1227 : {
1228 : unsigned long smin = task_scan_min(p);
1229 : unsigned long smax;
1230 : struct numa_group *ng;
1231 :
1232 : /* Watch for min being lower than max due to floor calculations */
1233 : smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p);
1234 :
1235 : /* Scale the maximum scan period with the amount of shared memory. */
1236 : ng = deref_curr_numa_group(p);
1237 : if (ng) {
1238 : unsigned long shared = group_faults_shared(ng);
1239 : unsigned long private = group_faults_priv(ng);
1240 : unsigned long period = smax;
1241 :
1242 : period *= refcount_read(&ng->refcount);
1243 : period *= shared + 1;
1244 : period /= private + shared + 1;
1245 :
1246 : smax = max(smax, period);
1247 : }
1248 :
1249 : return max(smin, smax);
1250 : }
1251 :
1252 : static void account_numa_enqueue(struct rq *rq, struct task_struct *p)
1253 : {
1254 : rq->nr_numa_running += (p->numa_preferred_nid != NUMA_NO_NODE);
1255 : rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p));
1256 : }
1257 :
1258 : static void account_numa_dequeue(struct rq *rq, struct task_struct *p)
1259 : {
1260 : rq->nr_numa_running -= (p->numa_preferred_nid != NUMA_NO_NODE);
1261 : rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p));
1262 : }
1263 :
1264 : /* Shared or private faults. */
1265 : #define NR_NUMA_HINT_FAULT_TYPES 2
1266 :
1267 : /* Memory and CPU locality */
1268 : #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2)
1269 :
1270 : /* Averaged statistics, and temporary buffers. */
1271 : #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2)
1272 :
1273 : pid_t task_numa_group_id(struct task_struct *p)
1274 : {
1275 : struct numa_group *ng;
1276 : pid_t gid = 0;
1277 :
1278 : rcu_read_lock();
1279 : ng = rcu_dereference(p->numa_group);
1280 : if (ng)
1281 : gid = ng->gid;
1282 : rcu_read_unlock();
1283 :
1284 : return gid;
1285 : }
1286 :
1287 : /*
1288 : * The averaged statistics, shared & private, memory & CPU,
1289 : * occupy the first half of the array. The second half of the
1290 : * array is for current counters, which are averaged into the
1291 : * first set by task_numa_placement.
1292 : */
1293 : static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv)
1294 : {
1295 : return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv;
1296 : }
1297 :
1298 : static inline unsigned long task_faults(struct task_struct *p, int nid)
1299 : {
1300 : if (!p->numa_faults)
1301 : return 0;
1302 :
1303 : return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] +
1304 : p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)];
1305 : }
1306 :
1307 : static inline unsigned long group_faults(struct task_struct *p, int nid)
1308 : {
1309 : struct numa_group *ng = deref_task_numa_group(p);
1310 :
1311 : if (!ng)
1312 : return 0;
1313 :
1314 : return ng->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
1315 : ng->faults[task_faults_idx(NUMA_MEM, nid, 1)];
1316 : }
1317 :
1318 : static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
1319 : {
1320 : return group->faults[task_faults_idx(NUMA_CPU, nid, 0)] +
1321 : group->faults[task_faults_idx(NUMA_CPU, nid, 1)];
1322 : }
1323 :
1324 : static inline unsigned long group_faults_priv(struct numa_group *ng)
1325 : {
1326 : unsigned long faults = 0;
1327 : int node;
1328 :
1329 : for_each_online_node(node) {
1330 : faults += ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
1331 : }
1332 :
1333 : return faults;
1334 : }
1335 :
1336 : static inline unsigned long group_faults_shared(struct numa_group *ng)
1337 : {
1338 : unsigned long faults = 0;
1339 : int node;
1340 :
1341 : for_each_online_node(node) {
1342 : faults += ng->faults[task_faults_idx(NUMA_MEM, node, 0)];
1343 : }
1344 :
1345 : return faults;
1346 : }
1347 :
1348 : /*
1349 : * A node triggering more than 1/3 as many NUMA faults as the maximum is
1350 : * considered part of a numa group's pseudo-interleaving set. Migrations
1351 : * between these nodes are slowed down, to allow things to settle down.
1352 : */
1353 : #define ACTIVE_NODE_FRACTION 3
1354 :
1355 : static bool numa_is_active_node(int nid, struct numa_group *ng)
1356 : {
1357 : return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu;
1358 : }
1359 :
1360 : /* Handle placement on systems where not all nodes are directly connected. */
1361 : static unsigned long score_nearby_nodes(struct task_struct *p, int nid,
1362 : int lim_dist, bool task)
1363 : {
1364 : unsigned long score = 0;
1365 : int node, max_dist;
1366 :
1367 : /*
1368 : * All nodes are directly connected, and the same distance
1369 : * from each other. No need for fancy placement algorithms.
1370 : */
1371 : if (sched_numa_topology_type == NUMA_DIRECT)
1372 : return 0;
1373 :
1374 : /* sched_max_numa_distance may be changed in parallel. */
1375 : max_dist = READ_ONCE(sched_max_numa_distance);
1376 : /*
1377 : * This code is called for each node, introducing N^2 complexity,
1378 : * which should be ok given the number of nodes rarely exceeds 8.
1379 : */
1380 : for_each_online_node(node) {
1381 : unsigned long faults;
1382 : int dist = node_distance(nid, node);
1383 :
1384 : /*
1385 : * The furthest away nodes in the system are not interesting
1386 : * for placement; nid was already counted.
1387 : */
1388 : if (dist >= max_dist || node == nid)
1389 : continue;
1390 :
1391 : /*
1392 : * On systems with a backplane NUMA topology, compare groups
1393 : * of nodes, and move tasks towards the group with the most
1394 : * memory accesses. When comparing two nodes at distance
1395 : * "hoplimit", only nodes closer by than "hoplimit" are part
1396 : * of each group. Skip other nodes.
1397 : */
1398 : if (sched_numa_topology_type == NUMA_BACKPLANE && dist >= lim_dist)
1399 : continue;
1400 :
1401 : /* Add up the faults from nearby nodes. */
1402 : if (task)
1403 : faults = task_faults(p, node);
1404 : else
1405 : faults = group_faults(p, node);
1406 :
1407 : /*
1408 : * On systems with a glueless mesh NUMA topology, there are
1409 : * no fixed "groups of nodes". Instead, nodes that are not
1410 : * directly connected bounce traffic through intermediate
1411 : * nodes; a numa_group can occupy any set of nodes.
1412 : * The further away a node is, the less the faults count.
1413 : * This seems to result in good task placement.
1414 : */
1415 : if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
1416 : faults *= (max_dist - dist);
1417 : faults /= (max_dist - LOCAL_DISTANCE);
1418 : }
1419 :
1420 : score += faults;
1421 : }
1422 :
1423 : return score;
1424 : }
1425 :
1426 : /*
1427 : * These return the fraction of accesses done by a particular task, or
1428 : * task group, on a particular numa node. The group weight is given a
1429 : * larger multiplier, in order to group tasks together that are almost
1430 : * evenly spread out between numa nodes.
1431 : */
1432 : static inline unsigned long task_weight(struct task_struct *p, int nid,
1433 : int dist)
1434 : {
1435 : unsigned long faults, total_faults;
1436 :
1437 : if (!p->numa_faults)
1438 : return 0;
1439 :
1440 : total_faults = p->total_numa_faults;
1441 :
1442 : if (!total_faults)
1443 : return 0;
1444 :
1445 : faults = task_faults(p, nid);
1446 : faults += score_nearby_nodes(p, nid, dist, true);
1447 :
1448 : return 1000 * faults / total_faults;
1449 : }
1450 :
1451 : static inline unsigned long group_weight(struct task_struct *p, int nid,
1452 : int dist)
1453 : {
1454 : struct numa_group *ng = deref_task_numa_group(p);
1455 : unsigned long faults, total_faults;
1456 :
1457 : if (!ng)
1458 : return 0;
1459 :
1460 : total_faults = ng->total_faults;
1461 :
1462 : if (!total_faults)
1463 : return 0;
1464 :
1465 : faults = group_faults(p, nid);
1466 : faults += score_nearby_nodes(p, nid, dist, false);
1467 :
1468 : return 1000 * faults / total_faults;
1469 : }
1470 :
1471 : /*
1472 : * If memory tiering mode is enabled, cpupid of slow memory page is
1473 : * used to record scan time instead of CPU and PID. When tiering mode
1474 : * is disabled at run time, the scan time (in cpupid) will be
1475 : * interpreted as CPU and PID. So CPU needs to be checked to avoid to
1476 : * access out of array bound.
1477 : */
1478 : static inline bool cpupid_valid(int cpupid)
1479 : {
1480 : return cpupid_to_cpu(cpupid) < nr_cpu_ids;
1481 : }
1482 :
1483 : /*
1484 : * For memory tiering mode, if there are enough free pages (more than
1485 : * enough watermark defined here) in fast memory node, to take full
1486 : * advantage of fast memory capacity, all recently accessed slow
1487 : * memory pages will be migrated to fast memory node without
1488 : * considering hot threshold.
1489 : */
1490 : static bool pgdat_free_space_enough(struct pglist_data *pgdat)
1491 : {
1492 : int z;
1493 : unsigned long enough_wmark;
1494 :
1495 : enough_wmark = max(1UL * 1024 * 1024 * 1024 >> PAGE_SHIFT,
1496 : pgdat->node_present_pages >> 4);
1497 : for (z = pgdat->nr_zones - 1; z >= 0; z--) {
1498 : struct zone *zone = pgdat->node_zones + z;
1499 :
1500 : if (!populated_zone(zone))
1501 : continue;
1502 :
1503 : if (zone_watermark_ok(zone, 0,
1504 : wmark_pages(zone, WMARK_PROMO) + enough_wmark,
1505 : ZONE_MOVABLE, 0))
1506 : return true;
1507 : }
1508 : return false;
1509 : }
1510 :
1511 : /*
1512 : * For memory tiering mode, when page tables are scanned, the scan
1513 : * time will be recorded in struct page in addition to make page
1514 : * PROT_NONE for slow memory page. So when the page is accessed, in
1515 : * hint page fault handler, the hint page fault latency is calculated
1516 : * via,
1517 : *
1518 : * hint page fault latency = hint page fault time - scan time
1519 : *
1520 : * The smaller the hint page fault latency, the higher the possibility
1521 : * for the page to be hot.
1522 : */
1523 : static int numa_hint_fault_latency(struct page *page)
1524 : {
1525 : int last_time, time;
1526 :
1527 : time = jiffies_to_msecs(jiffies);
1528 : last_time = xchg_page_access_time(page, time);
1529 :
1530 : return (time - last_time) & PAGE_ACCESS_TIME_MASK;
1531 : }
1532 :
1533 : /*
1534 : * For memory tiering mode, too high promotion/demotion throughput may
1535 : * hurt application latency. So we provide a mechanism to rate limit
1536 : * the number of pages that are tried to be promoted.
1537 : */
1538 : static bool numa_promotion_rate_limit(struct pglist_data *pgdat,
1539 : unsigned long rate_limit, int nr)
1540 : {
1541 : unsigned long nr_cand;
1542 : unsigned int now, start;
1543 :
1544 : now = jiffies_to_msecs(jiffies);
1545 : mod_node_page_state(pgdat, PGPROMOTE_CANDIDATE, nr);
1546 : nr_cand = node_page_state(pgdat, PGPROMOTE_CANDIDATE);
1547 : start = pgdat->nbp_rl_start;
1548 : if (now - start > MSEC_PER_SEC &&
1549 : cmpxchg(&pgdat->nbp_rl_start, start, now) == start)
1550 : pgdat->nbp_rl_nr_cand = nr_cand;
1551 : if (nr_cand - pgdat->nbp_rl_nr_cand >= rate_limit)
1552 : return true;
1553 : return false;
1554 : }
1555 :
1556 : #define NUMA_MIGRATION_ADJUST_STEPS 16
1557 :
1558 : static void numa_promotion_adjust_threshold(struct pglist_data *pgdat,
1559 : unsigned long rate_limit,
1560 : unsigned int ref_th)
1561 : {
1562 : unsigned int now, start, th_period, unit_th, th;
1563 : unsigned long nr_cand, ref_cand, diff_cand;
1564 :
1565 : now = jiffies_to_msecs(jiffies);
1566 : th_period = sysctl_numa_balancing_scan_period_max;
1567 : start = pgdat->nbp_th_start;
1568 : if (now - start > th_period &&
1569 : cmpxchg(&pgdat->nbp_th_start, start, now) == start) {
1570 : ref_cand = rate_limit *
1571 : sysctl_numa_balancing_scan_period_max / MSEC_PER_SEC;
1572 : nr_cand = node_page_state(pgdat, PGPROMOTE_CANDIDATE);
1573 : diff_cand = nr_cand - pgdat->nbp_th_nr_cand;
1574 : unit_th = ref_th * 2 / NUMA_MIGRATION_ADJUST_STEPS;
1575 : th = pgdat->nbp_threshold ? : ref_th;
1576 : if (diff_cand > ref_cand * 11 / 10)
1577 : th = max(th - unit_th, unit_th);
1578 : else if (diff_cand < ref_cand * 9 / 10)
1579 : th = min(th + unit_th, ref_th * 2);
1580 : pgdat->nbp_th_nr_cand = nr_cand;
1581 : pgdat->nbp_threshold = th;
1582 : }
1583 : }
1584 :
1585 : bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
1586 : int src_nid, int dst_cpu)
1587 : {
1588 : struct numa_group *ng = deref_curr_numa_group(p);
1589 : int dst_nid = cpu_to_node(dst_cpu);
1590 : int last_cpupid, this_cpupid;
1591 :
1592 : /*
1593 : * The pages in slow memory node should be migrated according
1594 : * to hot/cold instead of private/shared.
1595 : */
1596 : if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
1597 : !node_is_toptier(src_nid)) {
1598 : struct pglist_data *pgdat;
1599 : unsigned long rate_limit;
1600 : unsigned int latency, th, def_th;
1601 :
1602 : pgdat = NODE_DATA(dst_nid);
1603 : if (pgdat_free_space_enough(pgdat)) {
1604 : /* workload changed, reset hot threshold */
1605 : pgdat->nbp_threshold = 0;
1606 : return true;
1607 : }
1608 :
1609 : def_th = sysctl_numa_balancing_hot_threshold;
1610 : rate_limit = sysctl_numa_balancing_promote_rate_limit << \
1611 : (20 - PAGE_SHIFT);
1612 : numa_promotion_adjust_threshold(pgdat, rate_limit, def_th);
1613 :
1614 : th = pgdat->nbp_threshold ? : def_th;
1615 : latency = numa_hint_fault_latency(page);
1616 : if (latency >= th)
1617 : return false;
1618 :
1619 : return !numa_promotion_rate_limit(pgdat, rate_limit,
1620 : thp_nr_pages(page));
1621 : }
1622 :
1623 : this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
1624 : last_cpupid = page_cpupid_xchg_last(page, this_cpupid);
1625 :
1626 : if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
1627 : !node_is_toptier(src_nid) && !cpupid_valid(last_cpupid))
1628 : return false;
1629 :
1630 : /*
1631 : * Allow first faults or private faults to migrate immediately early in
1632 : * the lifetime of a task. The magic number 4 is based on waiting for
1633 : * two full passes of the "multi-stage node selection" test that is
1634 : * executed below.
1635 : */
1636 : if ((p->numa_preferred_nid == NUMA_NO_NODE || p->numa_scan_seq <= 4) &&
1637 : (cpupid_pid_unset(last_cpupid) || cpupid_match_pid(p, last_cpupid)))
1638 : return true;
1639 :
1640 : /*
1641 : * Multi-stage node selection is used in conjunction with a periodic
1642 : * migration fault to build a temporal task<->page relation. By using
1643 : * a two-stage filter we remove short/unlikely relations.
1644 : *
1645 : * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate
1646 : * a task's usage of a particular page (n_p) per total usage of this
1647 : * page (n_t) (in a given time-span) to a probability.
1648 : *
1649 : * Our periodic faults will sample this probability and getting the
1650 : * same result twice in a row, given these samples are fully
1651 : * independent, is then given by P(n)^2, provided our sample period
1652 : * is sufficiently short compared to the usage pattern.
1653 : *
1654 : * This quadric squishes small probabilities, making it less likely we
1655 : * act on an unlikely task<->page relation.
1656 : */
1657 : if (!cpupid_pid_unset(last_cpupid) &&
1658 : cpupid_to_nid(last_cpupid) != dst_nid)
1659 : return false;
1660 :
1661 : /* Always allow migrate on private faults */
1662 : if (cpupid_match_pid(p, last_cpupid))
1663 : return true;
1664 :
1665 : /* A shared fault, but p->numa_group has not been set up yet. */
1666 : if (!ng)
1667 : return true;
1668 :
1669 : /*
1670 : * Destination node is much more heavily used than the source
1671 : * node? Allow migration.
1672 : */
1673 : if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) *
1674 : ACTIVE_NODE_FRACTION)
1675 : return true;
1676 :
1677 : /*
1678 : * Distribute memory according to CPU & memory use on each node,
1679 : * with 3/4 hysteresis to avoid unnecessary memory migrations:
1680 : *
1681 : * faults_cpu(dst) 3 faults_cpu(src)
1682 : * --------------- * - > ---------------
1683 : * faults_mem(dst) 4 faults_mem(src)
1684 : */
1685 : return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 >
1686 : group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4;
1687 : }
1688 :
1689 : /*
1690 : * 'numa_type' describes the node at the moment of load balancing.
1691 : */
1692 : enum numa_type {
1693 : /* The node has spare capacity that can be used to run more tasks. */
1694 : node_has_spare = 0,
1695 : /*
1696 : * The node is fully used and the tasks don't compete for more CPU
1697 : * cycles. Nevertheless, some tasks might wait before running.
1698 : */
1699 : node_fully_busy,
1700 : /*
1701 : * The node is overloaded and can't provide expected CPU cycles to all
1702 : * tasks.
1703 : */
1704 : node_overloaded
1705 : };
1706 :
1707 : /* Cached statistics for all CPUs within a node */
1708 : struct numa_stats {
1709 : unsigned long load;
1710 : unsigned long runnable;
1711 : unsigned long util;
1712 : /* Total compute capacity of CPUs on a node */
1713 : unsigned long compute_capacity;
1714 : unsigned int nr_running;
1715 : unsigned int weight;
1716 : enum numa_type node_type;
1717 : int idle_cpu;
1718 : };
1719 :
1720 : struct task_numa_env {
1721 : struct task_struct *p;
1722 :
1723 : int src_cpu, src_nid;
1724 : int dst_cpu, dst_nid;
1725 : int imb_numa_nr;
1726 :
1727 : struct numa_stats src_stats, dst_stats;
1728 :
1729 : int imbalance_pct;
1730 : int dist;
1731 :
1732 : struct task_struct *best_task;
1733 : long best_imp;
1734 : int best_cpu;
1735 : };
1736 :
1737 : static unsigned long cpu_load(struct rq *rq);
1738 : static unsigned long cpu_runnable(struct rq *rq);
1739 :
1740 : static inline enum
1741 : numa_type numa_classify(unsigned int imbalance_pct,
1742 : struct numa_stats *ns)
1743 : {
1744 : if ((ns->nr_running > ns->weight) &&
1745 : (((ns->compute_capacity * 100) < (ns->util * imbalance_pct)) ||
1746 : ((ns->compute_capacity * imbalance_pct) < (ns->runnable * 100))))
1747 : return node_overloaded;
1748 :
1749 : if ((ns->nr_running < ns->weight) ||
1750 : (((ns->compute_capacity * 100) > (ns->util * imbalance_pct)) &&
1751 : ((ns->compute_capacity * imbalance_pct) > (ns->runnable * 100))))
1752 : return node_has_spare;
1753 :
1754 : return node_fully_busy;
1755 : }
1756 :
1757 : #ifdef CONFIG_SCHED_SMT
1758 : /* Forward declarations of select_idle_sibling helpers */
1759 : static inline bool test_idle_cores(int cpu);
1760 : static inline int numa_idle_core(int idle_core, int cpu)
1761 : {
1762 : if (!static_branch_likely(&sched_smt_present) ||
1763 : idle_core >= 0 || !test_idle_cores(cpu))
1764 : return idle_core;
1765 :
1766 : /*
1767 : * Prefer cores instead of packing HT siblings
1768 : * and triggering future load balancing.
1769 : */
1770 : if (is_core_idle(cpu))
1771 : idle_core = cpu;
1772 :
1773 : return idle_core;
1774 : }
1775 : #else
1776 : static inline int numa_idle_core(int idle_core, int cpu)
1777 : {
1778 : return idle_core;
1779 : }
1780 : #endif
1781 :
1782 : /*
1783 : * Gather all necessary information to make NUMA balancing placement
1784 : * decisions that are compatible with standard load balancer. This
1785 : * borrows code and logic from update_sg_lb_stats but sharing a
1786 : * common implementation is impractical.
1787 : */
1788 : static void update_numa_stats(struct task_numa_env *env,
1789 : struct numa_stats *ns, int nid,
1790 : bool find_idle)
1791 : {
1792 : int cpu, idle_core = -1;
1793 :
1794 : memset(ns, 0, sizeof(*ns));
1795 : ns->idle_cpu = -1;
1796 :
1797 : rcu_read_lock();
1798 : for_each_cpu(cpu, cpumask_of_node(nid)) {
1799 : struct rq *rq = cpu_rq(cpu);
1800 :
1801 : ns->load += cpu_load(rq);
1802 : ns->runnable += cpu_runnable(rq);
1803 : ns->util += cpu_util_cfs(cpu);
1804 : ns->nr_running += rq->cfs.h_nr_running;
1805 : ns->compute_capacity += capacity_of(cpu);
1806 :
1807 : if (find_idle && idle_core < 0 && !rq->nr_running && idle_cpu(cpu)) {
1808 : if (READ_ONCE(rq->numa_migrate_on) ||
1809 : !cpumask_test_cpu(cpu, env->p->cpus_ptr))
1810 : continue;
1811 :
1812 : if (ns->idle_cpu == -1)
1813 : ns->idle_cpu = cpu;
1814 :
1815 : idle_core = numa_idle_core(idle_core, cpu);
1816 : }
1817 : }
1818 : rcu_read_unlock();
1819 :
1820 : ns->weight = cpumask_weight(cpumask_of_node(nid));
1821 :
1822 : ns->node_type = numa_classify(env->imbalance_pct, ns);
1823 :
1824 : if (idle_core >= 0)
1825 : ns->idle_cpu = idle_core;
1826 : }
1827 :
1828 : static void task_numa_assign(struct task_numa_env *env,
1829 : struct task_struct *p, long imp)
1830 : {
1831 : struct rq *rq = cpu_rq(env->dst_cpu);
1832 :
1833 : /* Check if run-queue part of active NUMA balance. */
1834 : if (env->best_cpu != env->dst_cpu && xchg(&rq->numa_migrate_on, 1)) {
1835 : int cpu;
1836 : int start = env->dst_cpu;
1837 :
1838 : /* Find alternative idle CPU. */
1839 : for_each_cpu_wrap(cpu, cpumask_of_node(env->dst_nid), start + 1) {
1840 : if (cpu == env->best_cpu || !idle_cpu(cpu) ||
1841 : !cpumask_test_cpu(cpu, env->p->cpus_ptr)) {
1842 : continue;
1843 : }
1844 :
1845 : env->dst_cpu = cpu;
1846 : rq = cpu_rq(env->dst_cpu);
1847 : if (!xchg(&rq->numa_migrate_on, 1))
1848 : goto assign;
1849 : }
1850 :
1851 : /* Failed to find an alternative idle CPU */
1852 : return;
1853 : }
1854 :
1855 : assign:
1856 : /*
1857 : * Clear previous best_cpu/rq numa-migrate flag, since task now
1858 : * found a better CPU to move/swap.
1859 : */
1860 : if (env->best_cpu != -1 && env->best_cpu != env->dst_cpu) {
1861 : rq = cpu_rq(env->best_cpu);
1862 : WRITE_ONCE(rq->numa_migrate_on, 0);
1863 : }
1864 :
1865 : if (env->best_task)
1866 : put_task_struct(env->best_task);
1867 : if (p)
1868 : get_task_struct(p);
1869 :
1870 : env->best_task = p;
1871 : env->best_imp = imp;
1872 : env->best_cpu = env->dst_cpu;
1873 : }
1874 :
1875 : static bool load_too_imbalanced(long src_load, long dst_load,
1876 : struct task_numa_env *env)
1877 : {
1878 : long imb, old_imb;
1879 : long orig_src_load, orig_dst_load;
1880 : long src_capacity, dst_capacity;
1881 :
1882 : /*
1883 : * The load is corrected for the CPU capacity available on each node.
1884 : *
1885 : * src_load dst_load
1886 : * ------------ vs ---------
1887 : * src_capacity dst_capacity
1888 : */
1889 : src_capacity = env->src_stats.compute_capacity;
1890 : dst_capacity = env->dst_stats.compute_capacity;
1891 :
1892 : imb = abs(dst_load * src_capacity - src_load * dst_capacity);
1893 :
1894 : orig_src_load = env->src_stats.load;
1895 : orig_dst_load = env->dst_stats.load;
1896 :
1897 : old_imb = abs(orig_dst_load * src_capacity - orig_src_load * dst_capacity);
1898 :
1899 : /* Would this change make things worse? */
1900 : return (imb > old_imb);
1901 : }
1902 :
1903 : /*
1904 : * Maximum NUMA importance can be 1998 (2*999);
1905 : * SMALLIMP @ 30 would be close to 1998/64.
1906 : * Used to deter task migration.
1907 : */
1908 : #define SMALLIMP 30
1909 :
1910 : /*
1911 : * This checks if the overall compute and NUMA accesses of the system would
1912 : * be improved if the source tasks was migrated to the target dst_cpu taking
1913 : * into account that it might be best if task running on the dst_cpu should
1914 : * be exchanged with the source task
1915 : */
1916 : static bool task_numa_compare(struct task_numa_env *env,
1917 : long taskimp, long groupimp, bool maymove)
1918 : {
1919 : struct numa_group *cur_ng, *p_ng = deref_curr_numa_group(env->p);
1920 : struct rq *dst_rq = cpu_rq(env->dst_cpu);
1921 : long imp = p_ng ? groupimp : taskimp;
1922 : struct task_struct *cur;
1923 : long src_load, dst_load;
1924 : int dist = env->dist;
1925 : long moveimp = imp;
1926 : long load;
1927 : bool stopsearch = false;
1928 :
1929 : if (READ_ONCE(dst_rq->numa_migrate_on))
1930 : return false;
1931 :
1932 : rcu_read_lock();
1933 : cur = rcu_dereference(dst_rq->curr);
1934 : if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur)))
1935 : cur = NULL;
1936 :
1937 : /*
1938 : * Because we have preemption enabled we can get migrated around and
1939 : * end try selecting ourselves (current == env->p) as a swap candidate.
1940 : */
1941 : if (cur == env->p) {
1942 : stopsearch = true;
1943 : goto unlock;
1944 : }
1945 :
1946 : if (!cur) {
1947 : if (maymove && moveimp >= env->best_imp)
1948 : goto assign;
1949 : else
1950 : goto unlock;
1951 : }
1952 :
1953 : /* Skip this swap candidate if cannot move to the source cpu. */
1954 : if (!cpumask_test_cpu(env->src_cpu, cur->cpus_ptr))
1955 : goto unlock;
1956 :
1957 : /*
1958 : * Skip this swap candidate if it is not moving to its preferred
1959 : * node and the best task is.
1960 : */
1961 : if (env->best_task &&
1962 : env->best_task->numa_preferred_nid == env->src_nid &&
1963 : cur->numa_preferred_nid != env->src_nid) {
1964 : goto unlock;
1965 : }
1966 :
1967 : /*
1968 : * "imp" is the fault differential for the source task between the
1969 : * source and destination node. Calculate the total differential for
1970 : * the source task and potential destination task. The more negative
1971 : * the value is, the more remote accesses that would be expected to
1972 : * be incurred if the tasks were swapped.
1973 : *
1974 : * If dst and source tasks are in the same NUMA group, or not
1975 : * in any group then look only at task weights.
1976 : */
1977 : cur_ng = rcu_dereference(cur->numa_group);
1978 : if (cur_ng == p_ng) {
1979 : /*
1980 : * Do not swap within a group or between tasks that have
1981 : * no group if there is spare capacity. Swapping does
1982 : * not address the load imbalance and helps one task at
1983 : * the cost of punishing another.
1984 : */
1985 : if (env->dst_stats.node_type == node_has_spare)
1986 : goto unlock;
1987 :
1988 : imp = taskimp + task_weight(cur, env->src_nid, dist) -
1989 : task_weight(cur, env->dst_nid, dist);
1990 : /*
1991 : * Add some hysteresis to prevent swapping the
1992 : * tasks within a group over tiny differences.
1993 : */
1994 : if (cur_ng)
1995 : imp -= imp / 16;
1996 : } else {
1997 : /*
1998 : * Compare the group weights. If a task is all by itself
1999 : * (not part of a group), use the task weight instead.
2000 : */
2001 : if (cur_ng && p_ng)
2002 : imp += group_weight(cur, env->src_nid, dist) -
2003 : group_weight(cur, env->dst_nid, dist);
2004 : else
2005 : imp += task_weight(cur, env->src_nid, dist) -
2006 : task_weight(cur, env->dst_nid, dist);
2007 : }
2008 :
2009 : /* Discourage picking a task already on its preferred node */
2010 : if (cur->numa_preferred_nid == env->dst_nid)
2011 : imp -= imp / 16;
2012 :
2013 : /*
2014 : * Encourage picking a task that moves to its preferred node.
2015 : * This potentially makes imp larger than it's maximum of
2016 : * 1998 (see SMALLIMP and task_weight for why) but in this
2017 : * case, it does not matter.
2018 : */
2019 : if (cur->numa_preferred_nid == env->src_nid)
2020 : imp += imp / 8;
2021 :
2022 : if (maymove && moveimp > imp && moveimp > env->best_imp) {
2023 : imp = moveimp;
2024 : cur = NULL;
2025 : goto assign;
2026 : }
2027 :
2028 : /*
2029 : * Prefer swapping with a task moving to its preferred node over a
2030 : * task that is not.
2031 : */
2032 : if (env->best_task && cur->numa_preferred_nid == env->src_nid &&
2033 : env->best_task->numa_preferred_nid != env->src_nid) {
2034 : goto assign;
2035 : }
2036 :
2037 : /*
2038 : * If the NUMA importance is less than SMALLIMP,
2039 : * task migration might only result in ping pong
2040 : * of tasks and also hurt performance due to cache
2041 : * misses.
2042 : */
2043 : if (imp < SMALLIMP || imp <= env->best_imp + SMALLIMP / 2)
2044 : goto unlock;
2045 :
2046 : /*
2047 : * In the overloaded case, try and keep the load balanced.
2048 : */
2049 : load = task_h_load(env->p) - task_h_load(cur);
2050 : if (!load)
2051 : goto assign;
2052 :
2053 : dst_load = env->dst_stats.load + load;
2054 : src_load = env->src_stats.load - load;
2055 :
2056 : if (load_too_imbalanced(src_load, dst_load, env))
2057 : goto unlock;
2058 :
2059 : assign:
2060 : /* Evaluate an idle CPU for a task numa move. */
2061 : if (!cur) {
2062 : int cpu = env->dst_stats.idle_cpu;
2063 :
2064 : /* Nothing cached so current CPU went idle since the search. */
2065 : if (cpu < 0)
2066 : cpu = env->dst_cpu;
2067 :
2068 : /*
2069 : * If the CPU is no longer truly idle and the previous best CPU
2070 : * is, keep using it.
2071 : */
2072 : if (!idle_cpu(cpu) && env->best_cpu >= 0 &&
2073 : idle_cpu(env->best_cpu)) {
2074 : cpu = env->best_cpu;
2075 : }
2076 :
2077 : env->dst_cpu = cpu;
2078 : }
2079 :
2080 : task_numa_assign(env, cur, imp);
2081 :
2082 : /*
2083 : * If a move to idle is allowed because there is capacity or load
2084 : * balance improves then stop the search. While a better swap
2085 : * candidate may exist, a search is not free.
2086 : */
2087 : if (maymove && !cur && env->best_cpu >= 0 && idle_cpu(env->best_cpu))
2088 : stopsearch = true;
2089 :
2090 : /*
2091 : * If a swap candidate must be identified and the current best task
2092 : * moves its preferred node then stop the search.
2093 : */
2094 : if (!maymove && env->best_task &&
2095 : env->best_task->numa_preferred_nid == env->src_nid) {
2096 : stopsearch = true;
2097 : }
2098 : unlock:
2099 : rcu_read_unlock();
2100 :
2101 : return stopsearch;
2102 : }
2103 :
2104 : static void task_numa_find_cpu(struct task_numa_env *env,
2105 : long taskimp, long groupimp)
2106 : {
2107 : bool maymove = false;
2108 : int cpu;
2109 :
2110 : /*
2111 : * If dst node has spare capacity, then check if there is an
2112 : * imbalance that would be overruled by the load balancer.
2113 : */
2114 : if (env->dst_stats.node_type == node_has_spare) {
2115 : unsigned int imbalance;
2116 : int src_running, dst_running;
2117 :
2118 : /*
2119 : * Would movement cause an imbalance? Note that if src has
2120 : * more running tasks that the imbalance is ignored as the
2121 : * move improves the imbalance from the perspective of the
2122 : * CPU load balancer.
2123 : * */
2124 : src_running = env->src_stats.nr_running - 1;
2125 : dst_running = env->dst_stats.nr_running + 1;
2126 : imbalance = max(0, dst_running - src_running);
2127 : imbalance = adjust_numa_imbalance(imbalance, dst_running,
2128 : env->imb_numa_nr);
2129 :
2130 : /* Use idle CPU if there is no imbalance */
2131 : if (!imbalance) {
2132 : maymove = true;
2133 : if (env->dst_stats.idle_cpu >= 0) {
2134 : env->dst_cpu = env->dst_stats.idle_cpu;
2135 : task_numa_assign(env, NULL, 0);
2136 : return;
2137 : }
2138 : }
2139 : } else {
2140 : long src_load, dst_load, load;
2141 : /*
2142 : * If the improvement from just moving env->p direction is better
2143 : * than swapping tasks around, check if a move is possible.
2144 : */
2145 : load = task_h_load(env->p);
2146 : dst_load = env->dst_stats.load + load;
2147 : src_load = env->src_stats.load - load;
2148 : maymove = !load_too_imbalanced(src_load, dst_load, env);
2149 : }
2150 :
2151 : for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) {
2152 : /* Skip this CPU if the source task cannot migrate */
2153 : if (!cpumask_test_cpu(cpu, env->p->cpus_ptr))
2154 : continue;
2155 :
2156 : env->dst_cpu = cpu;
2157 : if (task_numa_compare(env, taskimp, groupimp, maymove))
2158 : break;
2159 : }
2160 : }
2161 :
2162 : static int task_numa_migrate(struct task_struct *p)
2163 : {
2164 : struct task_numa_env env = {
2165 : .p = p,
2166 :
2167 : .src_cpu = task_cpu(p),
2168 : .src_nid = task_node(p),
2169 :
2170 : .imbalance_pct = 112,
2171 :
2172 : .best_task = NULL,
2173 : .best_imp = 0,
2174 : .best_cpu = -1,
2175 : };
2176 : unsigned long taskweight, groupweight;
2177 : struct sched_domain *sd;
2178 : long taskimp, groupimp;
2179 : struct numa_group *ng;
2180 : struct rq *best_rq;
2181 : int nid, ret, dist;
2182 :
2183 : /*
2184 : * Pick the lowest SD_NUMA domain, as that would have the smallest
2185 : * imbalance and would be the first to start moving tasks about.
2186 : *
2187 : * And we want to avoid any moving of tasks about, as that would create
2188 : * random movement of tasks -- counter the numa conditions we're trying
2189 : * to satisfy here.
2190 : */
2191 : rcu_read_lock();
2192 : sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu));
2193 : if (sd) {
2194 : env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2;
2195 : env.imb_numa_nr = sd->imb_numa_nr;
2196 : }
2197 : rcu_read_unlock();
2198 :
2199 : /*
2200 : * Cpusets can break the scheduler domain tree into smaller
2201 : * balance domains, some of which do not cross NUMA boundaries.
2202 : * Tasks that are "trapped" in such domains cannot be migrated
2203 : * elsewhere, so there is no point in (re)trying.
2204 : */
2205 : if (unlikely(!sd)) {
2206 : sched_setnuma(p, task_node(p));
2207 : return -EINVAL;
2208 : }
2209 :
2210 : env.dst_nid = p->numa_preferred_nid;
2211 : dist = env.dist = node_distance(env.src_nid, env.dst_nid);
2212 : taskweight = task_weight(p, env.src_nid, dist);
2213 : groupweight = group_weight(p, env.src_nid, dist);
2214 : update_numa_stats(&env, &env.src_stats, env.src_nid, false);
2215 : taskimp = task_weight(p, env.dst_nid, dist) - taskweight;
2216 : groupimp = group_weight(p, env.dst_nid, dist) - groupweight;
2217 : update_numa_stats(&env, &env.dst_stats, env.dst_nid, true);
2218 :
2219 : /* Try to find a spot on the preferred nid. */
2220 : task_numa_find_cpu(&env, taskimp, groupimp);
2221 :
2222 : /*
2223 : * Look at other nodes in these cases:
2224 : * - there is no space available on the preferred_nid
2225 : * - the task is part of a numa_group that is interleaved across
2226 : * multiple NUMA nodes; in order to better consolidate the group,
2227 : * we need to check other locations.
2228 : */
2229 : ng = deref_curr_numa_group(p);
2230 : if (env.best_cpu == -1 || (ng && ng->active_nodes > 1)) {
2231 : for_each_node_state(nid, N_CPU) {
2232 : if (nid == env.src_nid || nid == p->numa_preferred_nid)
2233 : continue;
2234 :
2235 : dist = node_distance(env.src_nid, env.dst_nid);
2236 : if (sched_numa_topology_type == NUMA_BACKPLANE &&
2237 : dist != env.dist) {
2238 : taskweight = task_weight(p, env.src_nid, dist);
2239 : groupweight = group_weight(p, env.src_nid, dist);
2240 : }
2241 :
2242 : /* Only consider nodes where both task and groups benefit */
2243 : taskimp = task_weight(p, nid, dist) - taskweight;
2244 : groupimp = group_weight(p, nid, dist) - groupweight;
2245 : if (taskimp < 0 && groupimp < 0)
2246 : continue;
2247 :
2248 : env.dist = dist;
2249 : env.dst_nid = nid;
2250 : update_numa_stats(&env, &env.dst_stats, env.dst_nid, true);
2251 : task_numa_find_cpu(&env, taskimp, groupimp);
2252 : }
2253 : }
2254 :
2255 : /*
2256 : * If the task is part of a workload that spans multiple NUMA nodes,
2257 : * and is migrating into one of the workload's active nodes, remember
2258 : * this node as the task's preferred numa node, so the workload can
2259 : * settle down.
2260 : * A task that migrated to a second choice node will be better off
2261 : * trying for a better one later. Do not set the preferred node here.
2262 : */
2263 : if (ng) {
2264 : if (env.best_cpu == -1)
2265 : nid = env.src_nid;
2266 : else
2267 : nid = cpu_to_node(env.best_cpu);
2268 :
2269 : if (nid != p->numa_preferred_nid)
2270 : sched_setnuma(p, nid);
2271 : }
2272 :
2273 : /* No better CPU than the current one was found. */
2274 : if (env.best_cpu == -1) {
2275 : trace_sched_stick_numa(p, env.src_cpu, NULL, -1);
2276 : return -EAGAIN;
2277 : }
2278 :
2279 : best_rq = cpu_rq(env.best_cpu);
2280 : if (env.best_task == NULL) {
2281 : ret = migrate_task_to(p, env.best_cpu);
2282 : WRITE_ONCE(best_rq->numa_migrate_on, 0);
2283 : if (ret != 0)
2284 : trace_sched_stick_numa(p, env.src_cpu, NULL, env.best_cpu);
2285 : return ret;
2286 : }
2287 :
2288 : ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu);
2289 : WRITE_ONCE(best_rq->numa_migrate_on, 0);
2290 :
2291 : if (ret != 0)
2292 : trace_sched_stick_numa(p, env.src_cpu, env.best_task, env.best_cpu);
2293 : put_task_struct(env.best_task);
2294 : return ret;
2295 : }
2296 :
2297 : /* Attempt to migrate a task to a CPU on the preferred node. */
2298 : static void numa_migrate_preferred(struct task_struct *p)
2299 : {
2300 : unsigned long interval = HZ;
2301 :
2302 : /* This task has no NUMA fault statistics yet */
2303 : if (unlikely(p->numa_preferred_nid == NUMA_NO_NODE || !p->numa_faults))
2304 : return;
2305 :
2306 : /* Periodically retry migrating the task to the preferred node */
2307 : interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16);
2308 : p->numa_migrate_retry = jiffies + interval;
2309 :
2310 : /* Success if task is already running on preferred CPU */
2311 : if (task_node(p) == p->numa_preferred_nid)
2312 : return;
2313 :
2314 : /* Otherwise, try migrate to a CPU on the preferred node */
2315 : task_numa_migrate(p);
2316 : }
2317 :
2318 : /*
2319 : * Find out how many nodes the workload is actively running on. Do this by
2320 : * tracking the nodes from which NUMA hinting faults are triggered. This can
2321 : * be different from the set of nodes where the workload's memory is currently
2322 : * located.
2323 : */
2324 : static void numa_group_count_active_nodes(struct numa_group *numa_group)
2325 : {
2326 : unsigned long faults, max_faults = 0;
2327 : int nid, active_nodes = 0;
2328 :
2329 : for_each_node_state(nid, N_CPU) {
2330 : faults = group_faults_cpu(numa_group, nid);
2331 : if (faults > max_faults)
2332 : max_faults = faults;
2333 : }
2334 :
2335 : for_each_node_state(nid, N_CPU) {
2336 : faults = group_faults_cpu(numa_group, nid);
2337 : if (faults * ACTIVE_NODE_FRACTION > max_faults)
2338 : active_nodes++;
2339 : }
2340 :
2341 : numa_group->max_faults_cpu = max_faults;
2342 : numa_group->active_nodes = active_nodes;
2343 : }
2344 :
2345 : /*
2346 : * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS
2347 : * increments. The more local the fault statistics are, the higher the scan
2348 : * period will be for the next scan window. If local/(local+remote) ratio is
2349 : * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS)
2350 : * the scan period will decrease. Aim for 70% local accesses.
2351 : */
2352 : #define NUMA_PERIOD_SLOTS 10
2353 : #define NUMA_PERIOD_THRESHOLD 7
2354 :
2355 : /*
2356 : * Increase the scan period (slow down scanning) if the majority of
2357 : * our memory is already on our local node, or if the majority of
2358 : * the page accesses are shared with other processes.
2359 : * Otherwise, decrease the scan period.
2360 : */
2361 : static void update_task_scan_period(struct task_struct *p,
2362 : unsigned long shared, unsigned long private)
2363 : {
2364 : unsigned int period_slot;
2365 : int lr_ratio, ps_ratio;
2366 : int diff;
2367 :
2368 : unsigned long remote = p->numa_faults_locality[0];
2369 : unsigned long local = p->numa_faults_locality[1];
2370 :
2371 : /*
2372 : * If there were no record hinting faults then either the task is
2373 : * completely idle or all activity is in areas that are not of interest
2374 : * to automatic numa balancing. Related to that, if there were failed
2375 : * migration then it implies we are migrating too quickly or the local
2376 : * node is overloaded. In either case, scan slower
2377 : */
2378 : if (local + shared == 0 || p->numa_faults_locality[2]) {
2379 : p->numa_scan_period = min(p->numa_scan_period_max,
2380 : p->numa_scan_period << 1);
2381 :
2382 : p->mm->numa_next_scan = jiffies +
2383 : msecs_to_jiffies(p->numa_scan_period);
2384 :
2385 : return;
2386 : }
2387 :
2388 : /*
2389 : * Prepare to scale scan period relative to the current period.
2390 : * == NUMA_PERIOD_THRESHOLD scan period stays the same
2391 : * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster)
2392 : * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower)
2393 : */
2394 : period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS);
2395 : lr_ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote);
2396 : ps_ratio = (private * NUMA_PERIOD_SLOTS) / (private + shared);
2397 :
2398 : if (ps_ratio >= NUMA_PERIOD_THRESHOLD) {
2399 : /*
2400 : * Most memory accesses are local. There is no need to
2401 : * do fast NUMA scanning, since memory is already local.
2402 : */
2403 : int slot = ps_ratio - NUMA_PERIOD_THRESHOLD;
2404 : if (!slot)
2405 : slot = 1;
2406 : diff = slot * period_slot;
2407 : } else if (lr_ratio >= NUMA_PERIOD_THRESHOLD) {
2408 : /*
2409 : * Most memory accesses are shared with other tasks.
2410 : * There is no point in continuing fast NUMA scanning,
2411 : * since other tasks may just move the memory elsewhere.
2412 : */
2413 : int slot = lr_ratio - NUMA_PERIOD_THRESHOLD;
2414 : if (!slot)
2415 : slot = 1;
2416 : diff = slot * period_slot;
2417 : } else {
2418 : /*
2419 : * Private memory faults exceed (SLOTS-THRESHOLD)/SLOTS,
2420 : * yet they are not on the local NUMA node. Speed up
2421 : * NUMA scanning to get the memory moved over.
2422 : */
2423 : int ratio = max(lr_ratio, ps_ratio);
2424 : diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot;
2425 : }
2426 :
2427 : p->numa_scan_period = clamp(p->numa_scan_period + diff,
2428 : task_scan_min(p), task_scan_max(p));
2429 : memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
2430 : }
2431 :
2432 : /*
2433 : * Get the fraction of time the task has been running since the last
2434 : * NUMA placement cycle. The scheduler keeps similar statistics, but
2435 : * decays those on a 32ms period, which is orders of magnitude off
2436 : * from the dozens-of-seconds NUMA balancing period. Use the scheduler
2437 : * stats only if the task is so new there are no NUMA statistics yet.
2438 : */
2439 : static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
2440 : {
2441 : u64 runtime, delta, now;
2442 : /* Use the start of this time slice to avoid calculations. */
2443 : now = p->se.exec_start;
2444 : runtime = p->se.sum_exec_runtime;
2445 :
2446 : if (p->last_task_numa_placement) {
2447 : delta = runtime - p->last_sum_exec_runtime;
2448 : *period = now - p->last_task_numa_placement;
2449 :
2450 : /* Avoid time going backwards, prevent potential divide error: */
2451 : if (unlikely((s64)*period < 0))
2452 : *period = 0;
2453 : } else {
2454 : delta = p->se.avg.load_sum;
2455 : *period = LOAD_AVG_MAX;
2456 : }
2457 :
2458 : p->last_sum_exec_runtime = runtime;
2459 : p->last_task_numa_placement = now;
2460 :
2461 : return delta;
2462 : }
2463 :
2464 : /*
2465 : * Determine the preferred nid for a task in a numa_group. This needs to
2466 : * be done in a way that produces consistent results with group_weight,
2467 : * otherwise workloads might not converge.
2468 : */
2469 : static int preferred_group_nid(struct task_struct *p, int nid)
2470 : {
2471 : nodemask_t nodes;
2472 : int dist;
2473 :
2474 : /* Direct connections between all NUMA nodes. */
2475 : if (sched_numa_topology_type == NUMA_DIRECT)
2476 : return nid;
2477 :
2478 : /*
2479 : * On a system with glueless mesh NUMA topology, group_weight
2480 : * scores nodes according to the number of NUMA hinting faults on
2481 : * both the node itself, and on nearby nodes.
2482 : */
2483 : if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
2484 : unsigned long score, max_score = 0;
2485 : int node, max_node = nid;
2486 :
2487 : dist = sched_max_numa_distance;
2488 :
2489 : for_each_node_state(node, N_CPU) {
2490 : score = group_weight(p, node, dist);
2491 : if (score > max_score) {
2492 : max_score = score;
2493 : max_node = node;
2494 : }
2495 : }
2496 : return max_node;
2497 : }
2498 :
2499 : /*
2500 : * Finding the preferred nid in a system with NUMA backplane
2501 : * interconnect topology is more involved. The goal is to locate
2502 : * tasks from numa_groups near each other in the system, and
2503 : * untangle workloads from different sides of the system. This requires
2504 : * searching down the hierarchy of node groups, recursively searching
2505 : * inside the highest scoring group of nodes. The nodemask tricks
2506 : * keep the complexity of the search down.
2507 : */
2508 : nodes = node_states[N_CPU];
2509 : for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) {
2510 : unsigned long max_faults = 0;
2511 : nodemask_t max_group = NODE_MASK_NONE;
2512 : int a, b;
2513 :
2514 : /* Are there nodes at this distance from each other? */
2515 : if (!find_numa_distance(dist))
2516 : continue;
2517 :
2518 : for_each_node_mask(a, nodes) {
2519 : unsigned long faults = 0;
2520 : nodemask_t this_group;
2521 : nodes_clear(this_group);
2522 :
2523 : /* Sum group's NUMA faults; includes a==b case. */
2524 : for_each_node_mask(b, nodes) {
2525 : if (node_distance(a, b) < dist) {
2526 : faults += group_faults(p, b);
2527 : node_set(b, this_group);
2528 : node_clear(b, nodes);
2529 : }
2530 : }
2531 :
2532 : /* Remember the top group. */
2533 : if (faults > max_faults) {
2534 : max_faults = faults;
2535 : max_group = this_group;
2536 : /*
2537 : * subtle: at the smallest distance there is
2538 : * just one node left in each "group", the
2539 : * winner is the preferred nid.
2540 : */
2541 : nid = a;
2542 : }
2543 : }
2544 : /* Next round, evaluate the nodes within max_group. */
2545 : if (!max_faults)
2546 : break;
2547 : nodes = max_group;
2548 : }
2549 : return nid;
2550 : }
2551 :
2552 : static void task_numa_placement(struct task_struct *p)
2553 : {
2554 : int seq, nid, max_nid = NUMA_NO_NODE;
2555 : unsigned long max_faults = 0;
2556 : unsigned long fault_types[2] = { 0, 0 };
2557 : unsigned long total_faults;
2558 : u64 runtime, period;
2559 : spinlock_t *group_lock = NULL;
2560 : struct numa_group *ng;
2561 :
2562 : /*
2563 : * The p->mm->numa_scan_seq field gets updated without
2564 : * exclusive access. Use READ_ONCE() here to ensure
2565 : * that the field is read in a single access:
2566 : */
2567 : seq = READ_ONCE(p->mm->numa_scan_seq);
2568 : if (p->numa_scan_seq == seq)
2569 : return;
2570 : p->numa_scan_seq = seq;
2571 : p->numa_scan_period_max = task_scan_max(p);
2572 :
2573 : total_faults = p->numa_faults_locality[0] +
2574 : p->numa_faults_locality[1];
2575 : runtime = numa_get_avg_runtime(p, &period);
2576 :
2577 : /* If the task is part of a group prevent parallel updates to group stats */
2578 : ng = deref_curr_numa_group(p);
2579 : if (ng) {
2580 : group_lock = &ng->lock;
2581 : spin_lock_irq(group_lock);
2582 : }
2583 :
2584 : /* Find the node with the highest number of faults */
2585 : for_each_online_node(nid) {
2586 : /* Keep track of the offsets in numa_faults array */
2587 : int mem_idx, membuf_idx, cpu_idx, cpubuf_idx;
2588 : unsigned long faults = 0, group_faults = 0;
2589 : int priv;
2590 :
2591 : for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) {
2592 : long diff, f_diff, f_weight;
2593 :
2594 : mem_idx = task_faults_idx(NUMA_MEM, nid, priv);
2595 : membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv);
2596 : cpu_idx = task_faults_idx(NUMA_CPU, nid, priv);
2597 : cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv);
2598 :
2599 : /* Decay existing window, copy faults since last scan */
2600 : diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2;
2601 : fault_types[priv] += p->numa_faults[membuf_idx];
2602 : p->numa_faults[membuf_idx] = 0;
2603 :
2604 : /*
2605 : * Normalize the faults_from, so all tasks in a group
2606 : * count according to CPU use, instead of by the raw
2607 : * number of faults. Tasks with little runtime have
2608 : * little over-all impact on throughput, and thus their
2609 : * faults are less important.
2610 : */
2611 : f_weight = div64_u64(runtime << 16, period + 1);
2612 : f_weight = (f_weight * p->numa_faults[cpubuf_idx]) /
2613 : (total_faults + 1);
2614 : f_diff = f_weight - p->numa_faults[cpu_idx] / 2;
2615 : p->numa_faults[cpubuf_idx] = 0;
2616 :
2617 : p->numa_faults[mem_idx] += diff;
2618 : p->numa_faults[cpu_idx] += f_diff;
2619 : faults += p->numa_faults[mem_idx];
2620 : p->total_numa_faults += diff;
2621 : if (ng) {
2622 : /*
2623 : * safe because we can only change our own group
2624 : *
2625 : * mem_idx represents the offset for a given
2626 : * nid and priv in a specific region because it
2627 : * is at the beginning of the numa_faults array.
2628 : */
2629 : ng->faults[mem_idx] += diff;
2630 : ng->faults[cpu_idx] += f_diff;
2631 : ng->total_faults += diff;
2632 : group_faults += ng->faults[mem_idx];
2633 : }
2634 : }
2635 :
2636 : if (!ng) {
2637 : if (faults > max_faults) {
2638 : max_faults = faults;
2639 : max_nid = nid;
2640 : }
2641 : } else if (group_faults > max_faults) {
2642 : max_faults = group_faults;
2643 : max_nid = nid;
2644 : }
2645 : }
2646 :
2647 : /* Cannot migrate task to CPU-less node */
2648 : if (max_nid != NUMA_NO_NODE && !node_state(max_nid, N_CPU)) {
2649 : int near_nid = max_nid;
2650 : int distance, near_distance = INT_MAX;
2651 :
2652 : for_each_node_state(nid, N_CPU) {
2653 : distance = node_distance(max_nid, nid);
2654 : if (distance < near_distance) {
2655 : near_nid = nid;
2656 : near_distance = distance;
2657 : }
2658 : }
2659 : max_nid = near_nid;
2660 : }
2661 :
2662 : if (ng) {
2663 : numa_group_count_active_nodes(ng);
2664 : spin_unlock_irq(group_lock);
2665 : max_nid = preferred_group_nid(p, max_nid);
2666 : }
2667 :
2668 : if (max_faults) {
2669 : /* Set the new preferred node */
2670 : if (max_nid != p->numa_preferred_nid)
2671 : sched_setnuma(p, max_nid);
2672 : }
2673 :
2674 : update_task_scan_period(p, fault_types[0], fault_types[1]);
2675 : }
2676 :
2677 : static inline int get_numa_group(struct numa_group *grp)
2678 : {
2679 : return refcount_inc_not_zero(&grp->refcount);
2680 : }
2681 :
2682 : static inline void put_numa_group(struct numa_group *grp)
2683 : {
2684 : if (refcount_dec_and_test(&grp->refcount))
2685 : kfree_rcu(grp, rcu);
2686 : }
2687 :
2688 : static void task_numa_group(struct task_struct *p, int cpupid, int flags,
2689 : int *priv)
2690 : {
2691 : struct numa_group *grp, *my_grp;
2692 : struct task_struct *tsk;
2693 : bool join = false;
2694 : int cpu = cpupid_to_cpu(cpupid);
2695 : int i;
2696 :
2697 : if (unlikely(!deref_curr_numa_group(p))) {
2698 : unsigned int size = sizeof(struct numa_group) +
2699 : NR_NUMA_HINT_FAULT_STATS *
2700 : nr_node_ids * sizeof(unsigned long);
2701 :
2702 : grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
2703 : if (!grp)
2704 : return;
2705 :
2706 : refcount_set(&grp->refcount, 1);
2707 : grp->active_nodes = 1;
2708 : grp->max_faults_cpu = 0;
2709 : spin_lock_init(&grp->lock);
2710 : grp->gid = p->pid;
2711 :
2712 : for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
2713 : grp->faults[i] = p->numa_faults[i];
2714 :
2715 : grp->total_faults = p->total_numa_faults;
2716 :
2717 : grp->nr_tasks++;
2718 : rcu_assign_pointer(p->numa_group, grp);
2719 : }
2720 :
2721 : rcu_read_lock();
2722 : tsk = READ_ONCE(cpu_rq(cpu)->curr);
2723 :
2724 : if (!cpupid_match_pid(tsk, cpupid))
2725 : goto no_join;
2726 :
2727 : grp = rcu_dereference(tsk->numa_group);
2728 : if (!grp)
2729 : goto no_join;
2730 :
2731 : my_grp = deref_curr_numa_group(p);
2732 : if (grp == my_grp)
2733 : goto no_join;
2734 :
2735 : /*
2736 : * Only join the other group if its bigger; if we're the bigger group,
2737 : * the other task will join us.
2738 : */
2739 : if (my_grp->nr_tasks > grp->nr_tasks)
2740 : goto no_join;
2741 :
2742 : /*
2743 : * Tie-break on the grp address.
2744 : */
2745 : if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp)
2746 : goto no_join;
2747 :
2748 : /* Always join threads in the same process. */
2749 : if (tsk->mm == current->mm)
2750 : join = true;
2751 :
2752 : /* Simple filter to avoid false positives due to PID collisions */
2753 : if (flags & TNF_SHARED)
2754 : join = true;
2755 :
2756 : /* Update priv based on whether false sharing was detected */
2757 : *priv = !join;
2758 :
2759 : if (join && !get_numa_group(grp))
2760 : goto no_join;
2761 :
2762 : rcu_read_unlock();
2763 :
2764 : if (!join)
2765 : return;
2766 :
2767 : WARN_ON_ONCE(irqs_disabled());
2768 : double_lock_irq(&my_grp->lock, &grp->lock);
2769 :
2770 : for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
2771 : my_grp->faults[i] -= p->numa_faults[i];
2772 : grp->faults[i] += p->numa_faults[i];
2773 : }
2774 : my_grp->total_faults -= p->total_numa_faults;
2775 : grp->total_faults += p->total_numa_faults;
2776 :
2777 : my_grp->nr_tasks--;
2778 : grp->nr_tasks++;
2779 :
2780 : spin_unlock(&my_grp->lock);
2781 : spin_unlock_irq(&grp->lock);
2782 :
2783 : rcu_assign_pointer(p->numa_group, grp);
2784 :
2785 : put_numa_group(my_grp);
2786 : return;
2787 :
2788 : no_join:
2789 : rcu_read_unlock();
2790 : return;
2791 : }
2792 :
2793 : /*
2794 : * Get rid of NUMA statistics associated with a task (either current or dead).
2795 : * If @final is set, the task is dead and has reached refcount zero, so we can
2796 : * safely free all relevant data structures. Otherwise, there might be
2797 : * concurrent reads from places like load balancing and procfs, and we should
2798 : * reset the data back to default state without freeing ->numa_faults.
2799 : */
2800 : void task_numa_free(struct task_struct *p, bool final)
2801 : {
2802 : /* safe: p either is current or is being freed by current */
2803 : struct numa_group *grp = rcu_dereference_raw(p->numa_group);
2804 : unsigned long *numa_faults = p->numa_faults;
2805 : unsigned long flags;
2806 : int i;
2807 :
2808 : if (!numa_faults)
2809 : return;
2810 :
2811 : if (grp) {
2812 : spin_lock_irqsave(&grp->lock, flags);
2813 : for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
2814 : grp->faults[i] -= p->numa_faults[i];
2815 : grp->total_faults -= p->total_numa_faults;
2816 :
2817 : grp->nr_tasks--;
2818 : spin_unlock_irqrestore(&grp->lock, flags);
2819 : RCU_INIT_POINTER(p->numa_group, NULL);
2820 : put_numa_group(grp);
2821 : }
2822 :
2823 : if (final) {
2824 : p->numa_faults = NULL;
2825 : kfree(numa_faults);
2826 : } else {
2827 : p->total_numa_faults = 0;
2828 : for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
2829 : numa_faults[i] = 0;
2830 : }
2831 : }
2832 :
2833 : /*
2834 : * Got a PROT_NONE fault for a page on @node.
2835 : */
2836 : void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
2837 : {
2838 : struct task_struct *p = current;
2839 : bool migrated = flags & TNF_MIGRATED;
2840 : int cpu_node = task_node(current);
2841 : int local = !!(flags & TNF_FAULT_LOCAL);
2842 : struct numa_group *ng;
2843 : int priv;
2844 :
2845 : if (!static_branch_likely(&sched_numa_balancing))
2846 : return;
2847 :
2848 : /* for example, ksmd faulting in a user's mm */
2849 : if (!p->mm)
2850 : return;
2851 :
2852 : /*
2853 : * NUMA faults statistics are unnecessary for the slow memory
2854 : * node for memory tiering mode.
2855 : */
2856 : if (!node_is_toptier(mem_node) &&
2857 : (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ||
2858 : !cpupid_valid(last_cpupid)))
2859 : return;
2860 :
2861 : /* Allocate buffer to track faults on a per-node basis */
2862 : if (unlikely(!p->numa_faults)) {
2863 : int size = sizeof(*p->numa_faults) *
2864 : NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids;
2865 :
2866 : p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
2867 : if (!p->numa_faults)
2868 : return;
2869 :
2870 : p->total_numa_faults = 0;
2871 : memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
2872 : }
2873 :
2874 : /*
2875 : * First accesses are treated as private, otherwise consider accesses
2876 : * to be private if the accessing pid has not changed
2877 : */
2878 : if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) {
2879 : priv = 1;
2880 : } else {
2881 : priv = cpupid_match_pid(p, last_cpupid);
2882 : if (!priv && !(flags & TNF_NO_GROUP))
2883 : task_numa_group(p, last_cpupid, flags, &priv);
2884 : }
2885 :
2886 : /*
2887 : * If a workload spans multiple NUMA nodes, a shared fault that
2888 : * occurs wholly within the set of nodes that the workload is
2889 : * actively using should be counted as local. This allows the
2890 : * scan rate to slow down when a workload has settled down.
2891 : */
2892 : ng = deref_curr_numa_group(p);
2893 : if (!priv && !local && ng && ng->active_nodes > 1 &&
2894 : numa_is_active_node(cpu_node, ng) &&
2895 : numa_is_active_node(mem_node, ng))
2896 : local = 1;
2897 :
2898 : /*
2899 : * Retry to migrate task to preferred node periodically, in case it
2900 : * previously failed, or the scheduler moved us.
2901 : */
2902 : if (time_after(jiffies, p->numa_migrate_retry)) {
2903 : task_numa_placement(p);
2904 : numa_migrate_preferred(p);
2905 : }
2906 :
2907 : if (migrated)
2908 : p->numa_pages_migrated += pages;
2909 : if (flags & TNF_MIGRATE_FAIL)
2910 : p->numa_faults_locality[2] += pages;
2911 :
2912 : p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages;
2913 : p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages;
2914 : p->numa_faults_locality[local] += pages;
2915 : }
2916 :
2917 : static void reset_ptenuma_scan(struct task_struct *p)
2918 : {
2919 : /*
2920 : * We only did a read acquisition of the mmap sem, so
2921 : * p->mm->numa_scan_seq is written to without exclusive access
2922 : * and the update is not guaranteed to be atomic. That's not
2923 : * much of an issue though, since this is just used for
2924 : * statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not
2925 : * expensive, to avoid any form of compiler optimizations:
2926 : */
2927 : WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1);
2928 : p->mm->numa_scan_offset = 0;
2929 : }
2930 :
2931 : static bool vma_is_accessed(struct vm_area_struct *vma)
2932 : {
2933 : unsigned long pids;
2934 : /*
2935 : * Allow unconditional access first two times, so that all the (pages)
2936 : * of VMAs get prot_none fault introduced irrespective of accesses.
2937 : * This is also done to avoid any side effect of task scanning
2938 : * amplifying the unfairness of disjoint set of VMAs' access.
2939 : */
2940 : if (READ_ONCE(current->mm->numa_scan_seq) < 2)
2941 : return true;
2942 :
2943 : pids = vma->numab_state->access_pids[0] | vma->numab_state->access_pids[1];
2944 : return test_bit(hash_32(current->pid, ilog2(BITS_PER_LONG)), &pids);
2945 : }
2946 :
2947 : #define VMA_PID_RESET_PERIOD (4 * sysctl_numa_balancing_scan_delay)
2948 :
2949 : /*
2950 : * The expensive part of numa migration is done from task_work context.
2951 : * Triggered from task_tick_numa().
2952 : */
2953 : static void task_numa_work(struct callback_head *work)
2954 : {
2955 : unsigned long migrate, next_scan, now = jiffies;
2956 : struct task_struct *p = current;
2957 : struct mm_struct *mm = p->mm;
2958 : u64 runtime = p->se.sum_exec_runtime;
2959 : struct vm_area_struct *vma;
2960 : unsigned long start, end;
2961 : unsigned long nr_pte_updates = 0;
2962 : long pages, virtpages;
2963 : struct vma_iterator vmi;
2964 :
2965 : SCHED_WARN_ON(p != container_of(work, struct task_struct, numa_work));
2966 :
2967 : work->next = work;
2968 : /*
2969 : * Who cares about NUMA placement when they're dying.
2970 : *
2971 : * NOTE: make sure not to dereference p->mm before this check,
2972 : * exit_task_work() happens _after_ exit_mm() so we could be called
2973 : * without p->mm even though we still had it when we enqueued this
2974 : * work.
2975 : */
2976 : if (p->flags & PF_EXITING)
2977 : return;
2978 :
2979 : if (!mm->numa_next_scan) {
2980 : mm->numa_next_scan = now +
2981 : msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2982 : }
2983 :
2984 : /*
2985 : * Enforce maximal scan/migration frequency..
2986 : */
2987 : migrate = mm->numa_next_scan;
2988 : if (time_before(now, migrate))
2989 : return;
2990 :
2991 : if (p->numa_scan_period == 0) {
2992 : p->numa_scan_period_max = task_scan_max(p);
2993 : p->numa_scan_period = task_scan_start(p);
2994 : }
2995 :
2996 : next_scan = now + msecs_to_jiffies(p->numa_scan_period);
2997 : if (!try_cmpxchg(&mm->numa_next_scan, &migrate, next_scan))
2998 : return;
2999 :
3000 : /*
3001 : * Delay this task enough that another task of this mm will likely win
3002 : * the next time around.
3003 : */
3004 : p->node_stamp += 2 * TICK_NSEC;
3005 :
3006 : start = mm->numa_scan_offset;
3007 : pages = sysctl_numa_balancing_scan_size;
3008 : pages <<= 20 - PAGE_SHIFT; /* MB in pages */
3009 : virtpages = pages * 8; /* Scan up to this much virtual space */
3010 : if (!pages)
3011 : return;
3012 :
3013 :
3014 : if (!mmap_read_trylock(mm))
3015 : return;
3016 : vma_iter_init(&vmi, mm, start);
3017 : vma = vma_next(&vmi);
3018 : if (!vma) {
3019 : reset_ptenuma_scan(p);
3020 : start = 0;
3021 : vma_iter_set(&vmi, start);
3022 : vma = vma_next(&vmi);
3023 : }
3024 :
3025 : do {
3026 : if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
3027 : is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
3028 : continue;
3029 : }
3030 :
3031 : /*
3032 : * Shared library pages mapped by multiple processes are not
3033 : * migrated as it is expected they are cache replicated. Avoid
3034 : * hinting faults in read-only file-backed mappings or the vdso
3035 : * as migrating the pages will be of marginal benefit.
3036 : */
3037 : if (!vma->vm_mm ||
3038 : (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ)))
3039 : continue;
3040 :
3041 : /*
3042 : * Skip inaccessible VMAs to avoid any confusion between
3043 : * PROT_NONE and NUMA hinting ptes
3044 : */
3045 : if (!vma_is_accessible(vma))
3046 : continue;
3047 :
3048 : /* Initialise new per-VMA NUMAB state. */
3049 : if (!vma->numab_state) {
3050 : vma->numab_state = kzalloc(sizeof(struct vma_numab_state),
3051 : GFP_KERNEL);
3052 : if (!vma->numab_state)
3053 : continue;
3054 :
3055 : vma->numab_state->next_scan = now +
3056 : msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
3057 :
3058 : /* Reset happens after 4 times scan delay of scan start */
3059 : vma->numab_state->next_pid_reset = vma->numab_state->next_scan +
3060 : msecs_to_jiffies(VMA_PID_RESET_PERIOD);
3061 : }
3062 :
3063 : /*
3064 : * Scanning the VMA's of short lived tasks add more overhead. So
3065 : * delay the scan for new VMAs.
3066 : */
3067 : if (mm->numa_scan_seq && time_before(jiffies,
3068 : vma->numab_state->next_scan))
3069 : continue;
3070 :
3071 : /* Do not scan the VMA if task has not accessed */
3072 : if (!vma_is_accessed(vma))
3073 : continue;
3074 :
3075 : /*
3076 : * RESET access PIDs regularly for old VMAs. Resetting after checking
3077 : * vma for recent access to avoid clearing PID info before access..
3078 : */
3079 : if (mm->numa_scan_seq &&
3080 : time_after(jiffies, vma->numab_state->next_pid_reset)) {
3081 : vma->numab_state->next_pid_reset = vma->numab_state->next_pid_reset +
3082 : msecs_to_jiffies(VMA_PID_RESET_PERIOD);
3083 : vma->numab_state->access_pids[0] = READ_ONCE(vma->numab_state->access_pids[1]);
3084 : vma->numab_state->access_pids[1] = 0;
3085 : }
3086 :
3087 : do {
3088 : start = max(start, vma->vm_start);
3089 : end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
3090 : end = min(end, vma->vm_end);
3091 : nr_pte_updates = change_prot_numa(vma, start, end);
3092 :
3093 : /*
3094 : * Try to scan sysctl_numa_balancing_size worth of
3095 : * hpages that have at least one present PTE that
3096 : * is not already pte-numa. If the VMA contains
3097 : * areas that are unused or already full of prot_numa
3098 : * PTEs, scan up to virtpages, to skip through those
3099 : * areas faster.
3100 : */
3101 : if (nr_pte_updates)
3102 : pages -= (end - start) >> PAGE_SHIFT;
3103 : virtpages -= (end - start) >> PAGE_SHIFT;
3104 :
3105 : start = end;
3106 : if (pages <= 0 || virtpages <= 0)
3107 : goto out;
3108 :
3109 : cond_resched();
3110 : } while (end != vma->vm_end);
3111 : } for_each_vma(vmi, vma);
3112 :
3113 : out:
3114 : /*
3115 : * It is possible to reach the end of the VMA list but the last few
3116 : * VMAs are not guaranteed to the vma_migratable. If they are not, we
3117 : * would find the !migratable VMA on the next scan but not reset the
3118 : * scanner to the start so check it now.
3119 : */
3120 : if (vma)
3121 : mm->numa_scan_offset = start;
3122 : else
3123 : reset_ptenuma_scan(p);
3124 : mmap_read_unlock(mm);
3125 :
3126 : /*
3127 : * Make sure tasks use at least 32x as much time to run other code
3128 : * than they used here, to limit NUMA PTE scanning overhead to 3% max.
3129 : * Usually update_task_scan_period slows down scanning enough; on an
3130 : * overloaded system we need to limit overhead on a per task basis.
3131 : */
3132 : if (unlikely(p->se.sum_exec_runtime != runtime)) {
3133 : u64 diff = p->se.sum_exec_runtime - runtime;
3134 : p->node_stamp += 32 * diff;
3135 : }
3136 : }
3137 :
3138 : void init_numa_balancing(unsigned long clone_flags, struct task_struct *p)
3139 : {
3140 : int mm_users = 0;
3141 : struct mm_struct *mm = p->mm;
3142 :
3143 : if (mm) {
3144 : mm_users = atomic_read(&mm->mm_users);
3145 : if (mm_users == 1) {
3146 : mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
3147 : mm->numa_scan_seq = 0;
3148 : }
3149 : }
3150 : p->node_stamp = 0;
3151 : p->numa_scan_seq = mm ? mm->numa_scan_seq : 0;
3152 : p->numa_scan_period = sysctl_numa_balancing_scan_delay;
3153 : p->numa_migrate_retry = 0;
3154 : /* Protect against double add, see task_tick_numa and task_numa_work */
3155 : p->numa_work.next = &p->numa_work;
3156 : p->numa_faults = NULL;
3157 : p->numa_pages_migrated = 0;
3158 : p->total_numa_faults = 0;
3159 : RCU_INIT_POINTER(p->numa_group, NULL);
3160 : p->last_task_numa_placement = 0;
3161 : p->last_sum_exec_runtime = 0;
3162 :
3163 : init_task_work(&p->numa_work, task_numa_work);
3164 :
3165 : /* New address space, reset the preferred nid */
3166 : if (!(clone_flags & CLONE_VM)) {
3167 : p->numa_preferred_nid = NUMA_NO_NODE;
3168 : return;
3169 : }
3170 :
3171 : /*
3172 : * New thread, keep existing numa_preferred_nid which should be copied
3173 : * already by arch_dup_task_struct but stagger when scans start.
3174 : */
3175 : if (mm) {
3176 : unsigned int delay;
3177 :
3178 : delay = min_t(unsigned int, task_scan_max(current),
3179 : current->numa_scan_period * mm_users * NSEC_PER_MSEC);
3180 : delay += 2 * TICK_NSEC;
3181 : p->node_stamp = delay;
3182 : }
3183 : }
3184 :
3185 : /*
3186 : * Drive the periodic memory faults..
3187 : */
3188 : static void task_tick_numa(struct rq *rq, struct task_struct *curr)
3189 : {
3190 : struct callback_head *work = &curr->numa_work;
3191 : u64 period, now;
3192 :
3193 : /*
3194 : * We don't care about NUMA placement if we don't have memory.
3195 : */
3196 : if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work)
3197 : return;
3198 :
3199 : /*
3200 : * Using runtime rather than walltime has the dual advantage that
3201 : * we (mostly) drive the selection from busy threads and that the
3202 : * task needs to have done some actual work before we bother with
3203 : * NUMA placement.
3204 : */
3205 : now = curr->se.sum_exec_runtime;
3206 : period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
3207 :
3208 : if (now > curr->node_stamp + period) {
3209 : if (!curr->node_stamp)
3210 : curr->numa_scan_period = task_scan_start(curr);
3211 : curr->node_stamp += period;
3212 :
3213 : if (!time_before(jiffies, curr->mm->numa_next_scan))
3214 : task_work_add(curr, work, TWA_RESUME);
3215 : }
3216 : }
3217 :
3218 : static void update_scan_period(struct task_struct *p, int new_cpu)
3219 : {
3220 : int src_nid = cpu_to_node(task_cpu(p));
3221 : int dst_nid = cpu_to_node(new_cpu);
3222 :
3223 : if (!static_branch_likely(&sched_numa_balancing))
3224 : return;
3225 :
3226 : if (!p->mm || !p->numa_faults || (p->flags & PF_EXITING))
3227 : return;
3228 :
3229 : if (src_nid == dst_nid)
3230 : return;
3231 :
3232 : /*
3233 : * Allow resets if faults have been trapped before one scan
3234 : * has completed. This is most likely due to a new task that
3235 : * is pulled cross-node due to wakeups or load balancing.
3236 : */
3237 : if (p->numa_scan_seq) {
3238 : /*
3239 : * Avoid scan adjustments if moving to the preferred
3240 : * node or if the task was not previously running on
3241 : * the preferred node.
3242 : */
3243 : if (dst_nid == p->numa_preferred_nid ||
3244 : (p->numa_preferred_nid != NUMA_NO_NODE &&
3245 : src_nid != p->numa_preferred_nid))
3246 : return;
3247 : }
3248 :
3249 : p->numa_scan_period = task_scan_start(p);
3250 : }
3251 :
3252 : #else
3253 : static void task_tick_numa(struct rq *rq, struct task_struct *curr)
3254 : {
3255 : }
3256 :
3257 : static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p)
3258 : {
3259 : }
3260 :
3261 : static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p)
3262 : {
3263 : }
3264 :
3265 : static inline void update_scan_period(struct task_struct *p, int new_cpu)
3266 : {
3267 : }
3268 :
3269 : #endif /* CONFIG_NUMA_BALANCING */
3270 :
3271 : static void
3272 : account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
3273 : {
3274 2070 : update_load_add(&cfs_rq->load, se->load.weight);
3275 : #ifdef CONFIG_SMP
3276 : if (entity_is_task(se)) {
3277 : struct rq *rq = rq_of(cfs_rq);
3278 :
3279 : account_numa_enqueue(rq, task_of(se));
3280 : list_add(&se->group_node, &rq->cfs_tasks);
3281 : }
3282 : #endif
3283 1035 : cfs_rq->nr_running++;
3284 1035 : if (se_is_idle(se))
3285 : cfs_rq->idle_nr_running++;
3286 : }
3287 :
3288 : static void
3289 : account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
3290 : {
3291 2066 : update_load_sub(&cfs_rq->load, se->load.weight);
3292 : #ifdef CONFIG_SMP
3293 : if (entity_is_task(se)) {
3294 : account_numa_dequeue(rq_of(cfs_rq), task_of(se));
3295 : list_del_init(&se->group_node);
3296 : }
3297 : #endif
3298 1033 : cfs_rq->nr_running--;
3299 1033 : if (se_is_idle(se))
3300 : cfs_rq->idle_nr_running--;
3301 : }
3302 :
3303 : /*
3304 : * Signed add and clamp on underflow.
3305 : *
3306 : * Explicitly do a load-store to ensure the intermediate value never hits
3307 : * memory. This allows lockless observations without ever seeing the negative
3308 : * values.
3309 : */
3310 : #define add_positive(_ptr, _val) do { \
3311 : typeof(_ptr) ptr = (_ptr); \
3312 : typeof(_val) val = (_val); \
3313 : typeof(*ptr) res, var = READ_ONCE(*ptr); \
3314 : \
3315 : res = var + val; \
3316 : \
3317 : if (val < 0 && res > var) \
3318 : res = 0; \
3319 : \
3320 : WRITE_ONCE(*ptr, res); \
3321 : } while (0)
3322 :
3323 : /*
3324 : * Unsigned subtract and clamp on underflow.
3325 : *
3326 : * Explicitly do a load-store to ensure the intermediate value never hits
3327 : * memory. This allows lockless observations without ever seeing the negative
3328 : * values.
3329 : */
3330 : #define sub_positive(_ptr, _val) do { \
3331 : typeof(_ptr) ptr = (_ptr); \
3332 : typeof(*ptr) val = (_val); \
3333 : typeof(*ptr) res, var = READ_ONCE(*ptr); \
3334 : res = var - val; \
3335 : if (res > var) \
3336 : res = 0; \
3337 : WRITE_ONCE(*ptr, res); \
3338 : } while (0)
3339 :
3340 : /*
3341 : * Remove and clamp on negative, from a local variable.
3342 : *
3343 : * A variant of sub_positive(), which does not use explicit load-store
3344 : * and is thus optimized for local variable updates.
3345 : */
3346 : #define lsub_positive(_ptr, _val) do { \
3347 : typeof(_ptr) ptr = (_ptr); \
3348 : *ptr -= min_t(typeof(*ptr), *ptr, _val); \
3349 : } while (0)
3350 :
3351 : #ifdef CONFIG_SMP
3352 : static inline void
3353 : enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
3354 : {
3355 : cfs_rq->avg.load_avg += se->avg.load_avg;
3356 : cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
3357 : }
3358 :
3359 : static inline void
3360 : dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
3361 : {
3362 : sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
3363 : sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
3364 : /* See update_cfs_rq_load_avg() */
3365 : cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
3366 : cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
3367 : }
3368 : #else
3369 : static inline void
3370 : enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
3371 : static inline void
3372 : dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
3373 : #endif
3374 :
3375 5 : static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
3376 : unsigned long weight)
3377 : {
3378 5 : if (se->on_rq) {
3379 : /* commit outstanding execution time */
3380 0 : if (cfs_rq->curr == se)
3381 0 : update_curr(cfs_rq);
3382 0 : update_load_sub(&cfs_rq->load, se->load.weight);
3383 : }
3384 5 : dequeue_load_avg(cfs_rq, se);
3385 :
3386 10 : update_load_set(&se->load, weight);
3387 :
3388 : #ifdef CONFIG_SMP
3389 : do {
3390 : u32 divider = get_pelt_divider(&se->avg);
3391 :
3392 : se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
3393 : } while (0);
3394 : #endif
3395 :
3396 5 : enqueue_load_avg(cfs_rq, se);
3397 5 : if (se->on_rq)
3398 0 : update_load_add(&cfs_rq->load, se->load.weight);
3399 :
3400 5 : }
3401 :
3402 5 : void reweight_task(struct task_struct *p, int prio)
3403 : {
3404 5 : struct sched_entity *se = &p->se;
3405 10 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
3406 5 : struct load_weight *load = &se->load;
3407 5 : unsigned long weight = scale_load(sched_prio_to_weight[prio]);
3408 :
3409 5 : reweight_entity(cfs_rq, se, weight);
3410 5 : load->inv_weight = sched_prio_to_wmult[prio];
3411 5 : }
3412 :
3413 : static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
3414 :
3415 : #ifdef CONFIG_FAIR_GROUP_SCHED
3416 : #ifdef CONFIG_SMP
3417 : /*
3418 : * All this does is approximate the hierarchical proportion which includes that
3419 : * global sum we all love to hate.
3420 : *
3421 : * That is, the weight of a group entity, is the proportional share of the
3422 : * group weight based on the group runqueue weights. That is:
3423 : *
3424 : * tg->weight * grq->load.weight
3425 : * ge->load.weight = ----------------------------- (1)
3426 : * \Sum grq->load.weight
3427 : *
3428 : * Now, because computing that sum is prohibitively expensive to compute (been
3429 : * there, done that) we approximate it with this average stuff. The average
3430 : * moves slower and therefore the approximation is cheaper and more stable.
3431 : *
3432 : * So instead of the above, we substitute:
3433 : *
3434 : * grq->load.weight -> grq->avg.load_avg (2)
3435 : *
3436 : * which yields the following:
3437 : *
3438 : * tg->weight * grq->avg.load_avg
3439 : * ge->load.weight = ------------------------------ (3)
3440 : * tg->load_avg
3441 : *
3442 : * Where: tg->load_avg ~= \Sum grq->avg.load_avg
3443 : *
3444 : * That is shares_avg, and it is right (given the approximation (2)).
3445 : *
3446 : * The problem with it is that because the average is slow -- it was designed
3447 : * to be exactly that of course -- this leads to transients in boundary
3448 : * conditions. In specific, the case where the group was idle and we start the
3449 : * one task. It takes time for our CPU's grq->avg.load_avg to build up,
3450 : * yielding bad latency etc..
3451 : *
3452 : * Now, in that special case (1) reduces to:
3453 : *
3454 : * tg->weight * grq->load.weight
3455 : * ge->load.weight = ----------------------------- = tg->weight (4)
3456 : * grp->load.weight
3457 : *
3458 : * That is, the sum collapses because all other CPUs are idle; the UP scenario.
3459 : *
3460 : * So what we do is modify our approximation (3) to approach (4) in the (near)
3461 : * UP case, like:
3462 : *
3463 : * ge->load.weight =
3464 : *
3465 : * tg->weight * grq->load.weight
3466 : * --------------------------------------------------- (5)
3467 : * tg->load_avg - grq->avg.load_avg + grq->load.weight
3468 : *
3469 : * But because grq->load.weight can drop to 0, resulting in a divide by zero,
3470 : * we need to use grq->avg.load_avg as its lower bound, which then gives:
3471 : *
3472 : *
3473 : * tg->weight * grq->load.weight
3474 : * ge->load.weight = ----------------------------- (6)
3475 : * tg_load_avg'
3476 : *
3477 : * Where:
3478 : *
3479 : * tg_load_avg' = tg->load_avg - grq->avg.load_avg +
3480 : * max(grq->load.weight, grq->avg.load_avg)
3481 : *
3482 : * And that is shares_weight and is icky. In the (near) UP case it approaches
3483 : * (4) while in the normal case it approaches (3). It consistently
3484 : * overestimates the ge->load.weight and therefore:
3485 : *
3486 : * \Sum ge->load.weight >= tg->weight
3487 : *
3488 : * hence icky!
3489 : */
3490 : static long calc_group_shares(struct cfs_rq *cfs_rq)
3491 : {
3492 : long tg_weight, tg_shares, load, shares;
3493 : struct task_group *tg = cfs_rq->tg;
3494 :
3495 : tg_shares = READ_ONCE(tg->shares);
3496 :
3497 : load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
3498 :
3499 : tg_weight = atomic_long_read(&tg->load_avg);
3500 :
3501 : /* Ensure tg_weight >= load */
3502 : tg_weight -= cfs_rq->tg_load_avg_contrib;
3503 : tg_weight += load;
3504 :
3505 : shares = (tg_shares * load);
3506 : if (tg_weight)
3507 : shares /= tg_weight;
3508 :
3509 : /*
3510 : * MIN_SHARES has to be unscaled here to support per-CPU partitioning
3511 : * of a group with small tg->shares value. It is a floor value which is
3512 : * assigned as a minimum load.weight to the sched_entity representing
3513 : * the group on a CPU.
3514 : *
3515 : * E.g. on 64-bit for a group with tg->shares of scale_load(15)=15*1024
3516 : * on an 8-core system with 8 tasks each runnable on one CPU shares has
3517 : * to be 15*1024*1/8=1920 instead of scale_load(MIN_SHARES)=2*1024. In
3518 : * case no task is runnable on a CPU MIN_SHARES=2 should be returned
3519 : * instead of 0.
3520 : */
3521 : return clamp_t(long, shares, MIN_SHARES, tg_shares);
3522 : }
3523 : #endif /* CONFIG_SMP */
3524 :
3525 : /*
3526 : * Recomputes the group entity based on the current state of its group
3527 : * runqueue.
3528 : */
3529 : static void update_cfs_group(struct sched_entity *se)
3530 : {
3531 : struct cfs_rq *gcfs_rq = group_cfs_rq(se);
3532 : long shares;
3533 :
3534 : if (!gcfs_rq)
3535 : return;
3536 :
3537 : if (throttled_hierarchy(gcfs_rq))
3538 : return;
3539 :
3540 : #ifndef CONFIG_SMP
3541 : shares = READ_ONCE(gcfs_rq->tg->shares);
3542 :
3543 : if (likely(se->load.weight == shares))
3544 : return;
3545 : #else
3546 : shares = calc_group_shares(gcfs_rq);
3547 : #endif
3548 :
3549 : reweight_entity(cfs_rq_of(se), se, shares);
3550 : }
3551 :
3552 : #else /* CONFIG_FAIR_GROUP_SCHED */
3553 : static inline void update_cfs_group(struct sched_entity *se)
3554 : {
3555 : }
3556 : #endif /* CONFIG_FAIR_GROUP_SCHED */
3557 :
3558 : static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
3559 : {
3560 2069 : struct rq *rq = rq_of(cfs_rq);
3561 :
3562 : if (&rq->cfs == cfs_rq) {
3563 : /*
3564 : * There are a few boundary cases this might miss but it should
3565 : * get called often enough that that should (hopefully) not be
3566 : * a real problem.
3567 : *
3568 : * It will not get called when we go idle, because the idle
3569 : * thread is a different class (!fair), nor will the utilization
3570 : * number include things like RT tasks.
3571 : *
3572 : * As is, the util number is not freq-invariant (we'd have to
3573 : * implement arch_scale_freq_capacity() for that).
3574 : *
3575 : * See cpu_util_cfs().
3576 : */
3577 : cpufreq_update_util(rq, flags);
3578 : }
3579 : }
3580 :
3581 : #ifdef CONFIG_SMP
3582 : static inline bool load_avg_is_decayed(struct sched_avg *sa)
3583 : {
3584 : if (sa->load_sum)
3585 : return false;
3586 :
3587 : if (sa->util_sum)
3588 : return false;
3589 :
3590 : if (sa->runnable_sum)
3591 : return false;
3592 :
3593 : /*
3594 : * _avg must be null when _sum are null because _avg = _sum / divider
3595 : * Make sure that rounding and/or propagation of PELT values never
3596 : * break this.
3597 : */
3598 : SCHED_WARN_ON(sa->load_avg ||
3599 : sa->util_avg ||
3600 : sa->runnable_avg);
3601 :
3602 : return true;
3603 : }
3604 :
3605 : static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
3606 : {
3607 : return u64_u32_load_copy(cfs_rq->avg.last_update_time,
3608 : cfs_rq->last_update_time_copy);
3609 : }
3610 : #ifdef CONFIG_FAIR_GROUP_SCHED
3611 : /*
3612 : * Because list_add_leaf_cfs_rq always places a child cfs_rq on the list
3613 : * immediately before a parent cfs_rq, and cfs_rqs are removed from the list
3614 : * bottom-up, we only have to test whether the cfs_rq before us on the list
3615 : * is our child.
3616 : * If cfs_rq is not on the list, test whether a child needs its to be added to
3617 : * connect a branch to the tree * (see list_add_leaf_cfs_rq() for details).
3618 : */
3619 : static inline bool child_cfs_rq_on_list(struct cfs_rq *cfs_rq)
3620 : {
3621 : struct cfs_rq *prev_cfs_rq;
3622 : struct list_head *prev;
3623 :
3624 : if (cfs_rq->on_list) {
3625 : prev = cfs_rq->leaf_cfs_rq_list.prev;
3626 : } else {
3627 : struct rq *rq = rq_of(cfs_rq);
3628 :
3629 : prev = rq->tmp_alone_branch;
3630 : }
3631 :
3632 : prev_cfs_rq = container_of(prev, struct cfs_rq, leaf_cfs_rq_list);
3633 :
3634 : return (prev_cfs_rq->tg->parent == cfs_rq->tg);
3635 : }
3636 :
3637 : static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
3638 : {
3639 : if (cfs_rq->load.weight)
3640 : return false;
3641 :
3642 : if (!load_avg_is_decayed(&cfs_rq->avg))
3643 : return false;
3644 :
3645 : if (child_cfs_rq_on_list(cfs_rq))
3646 : return false;
3647 :
3648 : return true;
3649 : }
3650 :
3651 : /**
3652 : * update_tg_load_avg - update the tg's load avg
3653 : * @cfs_rq: the cfs_rq whose avg changed
3654 : *
3655 : * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load.
3656 : * However, because tg->load_avg is a global value there are performance
3657 : * considerations.
3658 : *
3659 : * In order to avoid having to look at the other cfs_rq's, we use a
3660 : * differential update where we store the last value we propagated. This in
3661 : * turn allows skipping updates if the differential is 'small'.
3662 : *
3663 : * Updating tg's load_avg is necessary before update_cfs_share().
3664 : */
3665 : static inline void update_tg_load_avg(struct cfs_rq *cfs_rq)
3666 : {
3667 : long delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
3668 :
3669 : /*
3670 : * No need to update load_avg for root_task_group as it is not used.
3671 : */
3672 : if (cfs_rq->tg == &root_task_group)
3673 : return;
3674 :
3675 : if (abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
3676 : atomic_long_add(delta, &cfs_rq->tg->load_avg);
3677 : cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
3678 : }
3679 : }
3680 :
3681 : /*
3682 : * Called within set_task_rq() right before setting a task's CPU. The
3683 : * caller only guarantees p->pi_lock is held; no other assumptions,
3684 : * including the state of rq->lock, should be made.
3685 : */
3686 : void set_task_rq_fair(struct sched_entity *se,
3687 : struct cfs_rq *prev, struct cfs_rq *next)
3688 : {
3689 : u64 p_last_update_time;
3690 : u64 n_last_update_time;
3691 :
3692 : if (!sched_feat(ATTACH_AGE_LOAD))
3693 : return;
3694 :
3695 : /*
3696 : * We are supposed to update the task to "current" time, then its up to
3697 : * date and ready to go to new CPU/cfs_rq. But we have difficulty in
3698 : * getting what current time is, so simply throw away the out-of-date
3699 : * time. This will result in the wakee task is less decayed, but giving
3700 : * the wakee more load sounds not bad.
3701 : */
3702 : if (!(se->avg.last_update_time && prev))
3703 : return;
3704 :
3705 : p_last_update_time = cfs_rq_last_update_time(prev);
3706 : n_last_update_time = cfs_rq_last_update_time(next);
3707 :
3708 : __update_load_avg_blocked_se(p_last_update_time, se);
3709 : se->avg.last_update_time = n_last_update_time;
3710 : }
3711 :
3712 : /*
3713 : * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
3714 : * propagate its contribution. The key to this propagation is the invariant
3715 : * that for each group:
3716 : *
3717 : * ge->avg == grq->avg (1)
3718 : *
3719 : * _IFF_ we look at the pure running and runnable sums. Because they
3720 : * represent the very same entity, just at different points in the hierarchy.
3721 : *
3722 : * Per the above update_tg_cfs_util() and update_tg_cfs_runnable() are trivial
3723 : * and simply copies the running/runnable sum over (but still wrong, because
3724 : * the group entity and group rq do not have their PELT windows aligned).
3725 : *
3726 : * However, update_tg_cfs_load() is more complex. So we have:
3727 : *
3728 : * ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg (2)
3729 : *
3730 : * And since, like util, the runnable part should be directly transferable,
3731 : * the following would _appear_ to be the straight forward approach:
3732 : *
3733 : * grq->avg.load_avg = grq->load.weight * grq->avg.runnable_avg (3)
3734 : *
3735 : * And per (1) we have:
3736 : *
3737 : * ge->avg.runnable_avg == grq->avg.runnable_avg
3738 : *
3739 : * Which gives:
3740 : *
3741 : * ge->load.weight * grq->avg.load_avg
3742 : * ge->avg.load_avg = ----------------------------------- (4)
3743 : * grq->load.weight
3744 : *
3745 : * Except that is wrong!
3746 : *
3747 : * Because while for entities historical weight is not important and we
3748 : * really only care about our future and therefore can consider a pure
3749 : * runnable sum, runqueues can NOT do this.
3750 : *
3751 : * We specifically want runqueues to have a load_avg that includes
3752 : * historical weights. Those represent the blocked load, the load we expect
3753 : * to (shortly) return to us. This only works by keeping the weights as
3754 : * integral part of the sum. We therefore cannot decompose as per (3).
3755 : *
3756 : * Another reason this doesn't work is that runnable isn't a 0-sum entity.
3757 : * Imagine a rq with 2 tasks that each are runnable 2/3 of the time. Then the
3758 : * rq itself is runnable anywhere between 2/3 and 1 depending on how the
3759 : * runnable section of these tasks overlap (or not). If they were to perfectly
3760 : * align the rq as a whole would be runnable 2/3 of the time. If however we
3761 : * always have at least 1 runnable task, the rq as a whole is always runnable.
3762 : *
3763 : * So we'll have to approximate.. :/
3764 : *
3765 : * Given the constraint:
3766 : *
3767 : * ge->avg.running_sum <= ge->avg.runnable_sum <= LOAD_AVG_MAX
3768 : *
3769 : * We can construct a rule that adds runnable to a rq by assuming minimal
3770 : * overlap.
3771 : *
3772 : * On removal, we'll assume each task is equally runnable; which yields:
3773 : *
3774 : * grq->avg.runnable_sum = grq->avg.load_sum / grq->load.weight
3775 : *
3776 : * XXX: only do this for the part of runnable > running ?
3777 : *
3778 : */
3779 : static inline void
3780 : update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
3781 : {
3782 : long delta_sum, delta_avg = gcfs_rq->avg.util_avg - se->avg.util_avg;
3783 : u32 new_sum, divider;
3784 :
3785 : /* Nothing to update */
3786 : if (!delta_avg)
3787 : return;
3788 :
3789 : /*
3790 : * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
3791 : * See ___update_load_avg() for details.
3792 : */
3793 : divider = get_pelt_divider(&cfs_rq->avg);
3794 :
3795 :
3796 : /* Set new sched_entity's utilization */
3797 : se->avg.util_avg = gcfs_rq->avg.util_avg;
3798 : new_sum = se->avg.util_avg * divider;
3799 : delta_sum = (long)new_sum - (long)se->avg.util_sum;
3800 : se->avg.util_sum = new_sum;
3801 :
3802 : /* Update parent cfs_rq utilization */
3803 : add_positive(&cfs_rq->avg.util_avg, delta_avg);
3804 : add_positive(&cfs_rq->avg.util_sum, delta_sum);
3805 :
3806 : /* See update_cfs_rq_load_avg() */
3807 : cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
3808 : cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
3809 : }
3810 :
3811 : static inline void
3812 : update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
3813 : {
3814 : long delta_sum, delta_avg = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
3815 : u32 new_sum, divider;
3816 :
3817 : /* Nothing to update */
3818 : if (!delta_avg)
3819 : return;
3820 :
3821 : /*
3822 : * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
3823 : * See ___update_load_avg() for details.
3824 : */
3825 : divider = get_pelt_divider(&cfs_rq->avg);
3826 :
3827 : /* Set new sched_entity's runnable */
3828 : se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
3829 : new_sum = se->avg.runnable_avg * divider;
3830 : delta_sum = (long)new_sum - (long)se->avg.runnable_sum;
3831 : se->avg.runnable_sum = new_sum;
3832 :
3833 : /* Update parent cfs_rq runnable */
3834 : add_positive(&cfs_rq->avg.runnable_avg, delta_avg);
3835 : add_positive(&cfs_rq->avg.runnable_sum, delta_sum);
3836 : /* See update_cfs_rq_load_avg() */
3837 : cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
3838 : cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
3839 : }
3840 :
3841 : static inline void
3842 : update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
3843 : {
3844 : long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;
3845 : unsigned long load_avg;
3846 : u64 load_sum = 0;
3847 : s64 delta_sum;
3848 : u32 divider;
3849 :
3850 : if (!runnable_sum)
3851 : return;
3852 :
3853 : gcfs_rq->prop_runnable_sum = 0;
3854 :
3855 : /*
3856 : * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
3857 : * See ___update_load_avg() for details.
3858 : */
3859 : divider = get_pelt_divider(&cfs_rq->avg);
3860 :
3861 : if (runnable_sum >= 0) {
3862 : /*
3863 : * Add runnable; clip at LOAD_AVG_MAX. Reflects that until
3864 : * the CPU is saturated running == runnable.
3865 : */
3866 : runnable_sum += se->avg.load_sum;
3867 : runnable_sum = min_t(long, runnable_sum, divider);
3868 : } else {
3869 : /*
3870 : * Estimate the new unweighted runnable_sum of the gcfs_rq by
3871 : * assuming all tasks are equally runnable.
3872 : */
3873 : if (scale_load_down(gcfs_rq->load.weight)) {
3874 : load_sum = div_u64(gcfs_rq->avg.load_sum,
3875 : scale_load_down(gcfs_rq->load.weight));
3876 : }
3877 :
3878 : /* But make sure to not inflate se's runnable */
3879 : runnable_sum = min(se->avg.load_sum, load_sum);
3880 : }
3881 :
3882 : /*
3883 : * runnable_sum can't be lower than running_sum
3884 : * Rescale running sum to be in the same range as runnable sum
3885 : * running_sum is in [0 : LOAD_AVG_MAX << SCHED_CAPACITY_SHIFT]
3886 : * runnable_sum is in [0 : LOAD_AVG_MAX]
3887 : */
3888 : running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;
3889 : runnable_sum = max(runnable_sum, running_sum);
3890 :
3891 : load_sum = se_weight(se) * runnable_sum;
3892 : load_avg = div_u64(load_sum, divider);
3893 :
3894 : delta_avg = load_avg - se->avg.load_avg;
3895 : if (!delta_avg)
3896 : return;
3897 :
3898 : delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
3899 :
3900 : se->avg.load_sum = runnable_sum;
3901 : se->avg.load_avg = load_avg;
3902 : add_positive(&cfs_rq->avg.load_avg, delta_avg);
3903 : add_positive(&cfs_rq->avg.load_sum, delta_sum);
3904 : /* See update_cfs_rq_load_avg() */
3905 : cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
3906 : cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
3907 : }
3908 :
3909 : static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
3910 : {
3911 : cfs_rq->propagate = 1;
3912 : cfs_rq->prop_runnable_sum += runnable_sum;
3913 : }
3914 :
3915 : /* Update task and its cfs_rq load average */
3916 : static inline int propagate_entity_load_avg(struct sched_entity *se)
3917 : {
3918 : struct cfs_rq *cfs_rq, *gcfs_rq;
3919 :
3920 : if (entity_is_task(se))
3921 : return 0;
3922 :
3923 : gcfs_rq = group_cfs_rq(se);
3924 : if (!gcfs_rq->propagate)
3925 : return 0;
3926 :
3927 : gcfs_rq->propagate = 0;
3928 :
3929 : cfs_rq = cfs_rq_of(se);
3930 :
3931 : add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
3932 :
3933 : update_tg_cfs_util(cfs_rq, se, gcfs_rq);
3934 : update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
3935 : update_tg_cfs_load(cfs_rq, se, gcfs_rq);
3936 :
3937 : trace_pelt_cfs_tp(cfs_rq);
3938 : trace_pelt_se_tp(se);
3939 :
3940 : return 1;
3941 : }
3942 :
3943 : /*
3944 : * Check if we need to update the load and the utilization of a blocked
3945 : * group_entity:
3946 : */
3947 : static inline bool skip_blocked_update(struct sched_entity *se)
3948 : {
3949 : struct cfs_rq *gcfs_rq = group_cfs_rq(se);
3950 :
3951 : /*
3952 : * If sched_entity still have not zero load or utilization, we have to
3953 : * decay it:
3954 : */
3955 : if (se->avg.load_avg || se->avg.util_avg)
3956 : return false;
3957 :
3958 : /*
3959 : * If there is a pending propagation, we have to update the load and
3960 : * the utilization of the sched_entity:
3961 : */
3962 : if (gcfs_rq->propagate)
3963 : return false;
3964 :
3965 : /*
3966 : * Otherwise, the load and the utilization of the sched_entity is
3967 : * already zero and there is no pending propagation, so it will be a
3968 : * waste of time to try to decay it:
3969 : */
3970 : return true;
3971 : }
3972 :
3973 : #else /* CONFIG_FAIR_GROUP_SCHED */
3974 :
3975 : static inline void update_tg_load_avg(struct cfs_rq *cfs_rq) {}
3976 :
3977 : static inline int propagate_entity_load_avg(struct sched_entity *se)
3978 : {
3979 : return 0;
3980 : }
3981 :
3982 : static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
3983 :
3984 : #endif /* CONFIG_FAIR_GROUP_SCHED */
3985 :
3986 : #ifdef CONFIG_NO_HZ_COMMON
3987 : static inline void migrate_se_pelt_lag(struct sched_entity *se)
3988 : {
3989 : u64 throttled = 0, now, lut;
3990 : struct cfs_rq *cfs_rq;
3991 : struct rq *rq;
3992 : bool is_idle;
3993 :
3994 : if (load_avg_is_decayed(&se->avg))
3995 : return;
3996 :
3997 : cfs_rq = cfs_rq_of(se);
3998 : rq = rq_of(cfs_rq);
3999 :
4000 : rcu_read_lock();
4001 : is_idle = is_idle_task(rcu_dereference(rq->curr));
4002 : rcu_read_unlock();
4003 :
4004 : /*
4005 : * The lag estimation comes with a cost we don't want to pay all the
4006 : * time. Hence, limiting to the case where the source CPU is idle and
4007 : * we know we are at the greatest risk to have an outdated clock.
4008 : */
4009 : if (!is_idle)
4010 : return;
4011 :
4012 : /*
4013 : * Estimated "now" is: last_update_time + cfs_idle_lag + rq_idle_lag, where:
4014 : *
4015 : * last_update_time (the cfs_rq's last_update_time)
4016 : * = cfs_rq_clock_pelt()@cfs_rq_idle
4017 : * = rq_clock_pelt()@cfs_rq_idle
4018 : * - cfs->throttled_clock_pelt_time@cfs_rq_idle
4019 : *
4020 : * cfs_idle_lag (delta between rq's update and cfs_rq's update)
4021 : * = rq_clock_pelt()@rq_idle - rq_clock_pelt()@cfs_rq_idle
4022 : *
4023 : * rq_idle_lag (delta between now and rq's update)
4024 : * = sched_clock_cpu() - rq_clock()@rq_idle
4025 : *
4026 : * We can then write:
4027 : *
4028 : * now = rq_clock_pelt()@rq_idle - cfs->throttled_clock_pelt_time +
4029 : * sched_clock_cpu() - rq_clock()@rq_idle
4030 : * Where:
4031 : * rq_clock_pelt()@rq_idle is rq->clock_pelt_idle
4032 : * rq_clock()@rq_idle is rq->clock_idle
4033 : * cfs->throttled_clock_pelt_time@cfs_rq_idle
4034 : * is cfs_rq->throttled_pelt_idle
4035 : */
4036 :
4037 : #ifdef CONFIG_CFS_BANDWIDTH
4038 : throttled = u64_u32_load(cfs_rq->throttled_pelt_idle);
4039 : /* The clock has been stopped for throttling */
4040 : if (throttled == U64_MAX)
4041 : return;
4042 : #endif
4043 : now = u64_u32_load(rq->clock_pelt_idle);
4044 : /*
4045 : * Paired with _update_idle_rq_clock_pelt(). It ensures at the worst case
4046 : * is observed the old clock_pelt_idle value and the new clock_idle,
4047 : * which lead to an underestimation. The opposite would lead to an
4048 : * overestimation.
4049 : */
4050 : smp_rmb();
4051 : lut = cfs_rq_last_update_time(cfs_rq);
4052 :
4053 : now -= throttled;
4054 : if (now < lut)
4055 : /*
4056 : * cfs_rq->avg.last_update_time is more recent than our
4057 : * estimation, let's use it.
4058 : */
4059 : now = lut;
4060 : else
4061 : now += sched_clock_cpu(cpu_of(rq)) - u64_u32_load(rq->clock_idle);
4062 :
4063 : __update_load_avg_blocked_se(now, se);
4064 : }
4065 : #else
4066 : static void migrate_se_pelt_lag(struct sched_entity *se) {}
4067 : #endif
4068 :
4069 : /**
4070 : * update_cfs_rq_load_avg - update the cfs_rq's load/util averages
4071 : * @now: current time, as per cfs_rq_clock_pelt()
4072 : * @cfs_rq: cfs_rq to update
4073 : *
4074 : * The cfs_rq avg is the direct sum of all its entities (blocked and runnable)
4075 : * avg. The immediate corollary is that all (fair) tasks must be attached.
4076 : *
4077 : * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example.
4078 : *
4079 : * Return: true if the load decayed or we removed load.
4080 : *
4081 : * Since both these conditions indicate a changed cfs_rq->avg.load we should
4082 : * call update_tg_load_avg() when this function returns true.
4083 : */
4084 : static inline int
4085 : update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
4086 : {
4087 : unsigned long removed_load = 0, removed_util = 0, removed_runnable = 0;
4088 : struct sched_avg *sa = &cfs_rq->avg;
4089 : int decayed = 0;
4090 :
4091 : if (cfs_rq->removed.nr) {
4092 : unsigned long r;
4093 : u32 divider = get_pelt_divider(&cfs_rq->avg);
4094 :
4095 : raw_spin_lock(&cfs_rq->removed.lock);
4096 : swap(cfs_rq->removed.util_avg, removed_util);
4097 : swap(cfs_rq->removed.load_avg, removed_load);
4098 : swap(cfs_rq->removed.runnable_avg, removed_runnable);
4099 : cfs_rq->removed.nr = 0;
4100 : raw_spin_unlock(&cfs_rq->removed.lock);
4101 :
4102 : r = removed_load;
4103 : sub_positive(&sa->load_avg, r);
4104 : sub_positive(&sa->load_sum, r * divider);
4105 : /* See sa->util_sum below */
4106 : sa->load_sum = max_t(u32, sa->load_sum, sa->load_avg * PELT_MIN_DIVIDER);
4107 :
4108 : r = removed_util;
4109 : sub_positive(&sa->util_avg, r);
4110 : sub_positive(&sa->util_sum, r * divider);
4111 : /*
4112 : * Because of rounding, se->util_sum might ends up being +1 more than
4113 : * cfs->util_sum. Although this is not a problem by itself, detaching
4114 : * a lot of tasks with the rounding problem between 2 updates of
4115 : * util_avg (~1ms) can make cfs->util_sum becoming null whereas
4116 : * cfs_util_avg is not.
4117 : * Check that util_sum is still above its lower bound for the new
4118 : * util_avg. Given that period_contrib might have moved since the last
4119 : * sync, we are only sure that util_sum must be above or equal to
4120 : * util_avg * minimum possible divider
4121 : */
4122 : sa->util_sum = max_t(u32, sa->util_sum, sa->util_avg * PELT_MIN_DIVIDER);
4123 :
4124 : r = removed_runnable;
4125 : sub_positive(&sa->runnable_avg, r);
4126 : sub_positive(&sa->runnable_sum, r * divider);
4127 : /* See sa->util_sum above */
4128 : sa->runnable_sum = max_t(u32, sa->runnable_sum,
4129 : sa->runnable_avg * PELT_MIN_DIVIDER);
4130 :
4131 : /*
4132 : * removed_runnable is the unweighted version of removed_load so we
4133 : * can use it to estimate removed_load_sum.
4134 : */
4135 : add_tg_cfs_propagate(cfs_rq,
4136 : -(long)(removed_runnable * divider) >> SCHED_CAPACITY_SHIFT);
4137 :
4138 : decayed = 1;
4139 : }
4140 :
4141 : decayed |= __update_load_avg_cfs_rq(now, cfs_rq);
4142 : u64_u32_store_copy(sa->last_update_time,
4143 : cfs_rq->last_update_time_copy,
4144 : sa->last_update_time);
4145 : return decayed;
4146 : }
4147 :
4148 : /**
4149 : * attach_entity_load_avg - attach this entity to its cfs_rq load avg
4150 : * @cfs_rq: cfs_rq to attach to
4151 : * @se: sched_entity to attach
4152 : *
4153 : * Must call update_cfs_rq_load_avg() before this, since we rely on
4154 : * cfs_rq->avg.last_update_time being current.
4155 : */
4156 : static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
4157 : {
4158 : /*
4159 : * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
4160 : * See ___update_load_avg() for details.
4161 : */
4162 : u32 divider = get_pelt_divider(&cfs_rq->avg);
4163 :
4164 : /*
4165 : * When we attach the @se to the @cfs_rq, we must align the decay
4166 : * window because without that, really weird and wonderful things can
4167 : * happen.
4168 : *
4169 : * XXX illustrate
4170 : */
4171 : se->avg.last_update_time = cfs_rq->avg.last_update_time;
4172 : se->avg.period_contrib = cfs_rq->avg.period_contrib;
4173 :
4174 : /*
4175 : * Hell(o) Nasty stuff.. we need to recompute _sum based on the new
4176 : * period_contrib. This isn't strictly correct, but since we're
4177 : * entirely outside of the PELT hierarchy, nobody cares if we truncate
4178 : * _sum a little.
4179 : */
4180 : se->avg.util_sum = se->avg.util_avg * divider;
4181 :
4182 : se->avg.runnable_sum = se->avg.runnable_avg * divider;
4183 :
4184 : se->avg.load_sum = se->avg.load_avg * divider;
4185 : if (se_weight(se) < se->avg.load_sum)
4186 : se->avg.load_sum = div_u64(se->avg.load_sum, se_weight(se));
4187 : else
4188 : se->avg.load_sum = 1;
4189 :
4190 : enqueue_load_avg(cfs_rq, se);
4191 : cfs_rq->avg.util_avg += se->avg.util_avg;
4192 : cfs_rq->avg.util_sum += se->avg.util_sum;
4193 : cfs_rq->avg.runnable_avg += se->avg.runnable_avg;
4194 : cfs_rq->avg.runnable_sum += se->avg.runnable_sum;
4195 :
4196 : add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
4197 :
4198 : cfs_rq_util_change(cfs_rq, 0);
4199 :
4200 : trace_pelt_cfs_tp(cfs_rq);
4201 : }
4202 :
4203 : /**
4204 : * detach_entity_load_avg - detach this entity from its cfs_rq load avg
4205 : * @cfs_rq: cfs_rq to detach from
4206 : * @se: sched_entity to detach
4207 : *
4208 : * Must call update_cfs_rq_load_avg() before this, since we rely on
4209 : * cfs_rq->avg.last_update_time being current.
4210 : */
4211 : static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
4212 : {
4213 : dequeue_load_avg(cfs_rq, se);
4214 : sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg);
4215 : sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum);
4216 : /* See update_cfs_rq_load_avg() */
4217 : cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
4218 : cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
4219 :
4220 : sub_positive(&cfs_rq->avg.runnable_avg, se->avg.runnable_avg);
4221 : sub_positive(&cfs_rq->avg.runnable_sum, se->avg.runnable_sum);
4222 : /* See update_cfs_rq_load_avg() */
4223 : cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
4224 : cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
4225 :
4226 : add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
4227 :
4228 : cfs_rq_util_change(cfs_rq, 0);
4229 :
4230 : trace_pelt_cfs_tp(cfs_rq);
4231 : }
4232 :
4233 : /*
4234 : * Optional action to be done while updating the load average
4235 : */
4236 : #define UPDATE_TG 0x1
4237 : #define SKIP_AGE_LOAD 0x2
4238 : #define DO_ATTACH 0x4
4239 : #define DO_DETACH 0x8
4240 :
4241 : /* Update task and its cfs_rq load average */
4242 : static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
4243 : {
4244 : u64 now = cfs_rq_clock_pelt(cfs_rq);
4245 : int decayed;
4246 :
4247 : /*
4248 : * Track task load average for carrying it to new CPU after migrated, and
4249 : * track group sched_entity load average for task_h_load calc in migration
4250 : */
4251 : if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
4252 : __update_load_avg_se(now, cfs_rq, se);
4253 :
4254 : decayed = update_cfs_rq_load_avg(now, cfs_rq);
4255 : decayed |= propagate_entity_load_avg(se);
4256 :
4257 : if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
4258 :
4259 : /*
4260 : * DO_ATTACH means we're here from enqueue_entity().
4261 : * !last_update_time means we've passed through
4262 : * migrate_task_rq_fair() indicating we migrated.
4263 : *
4264 : * IOW we're enqueueing a task on a new CPU.
4265 : */
4266 : attach_entity_load_avg(cfs_rq, se);
4267 : update_tg_load_avg(cfs_rq);
4268 :
4269 : } else if (flags & DO_DETACH) {
4270 : /*
4271 : * DO_DETACH means we're here from dequeue_entity()
4272 : * and we are migrating task out of the CPU.
4273 : */
4274 : detach_entity_load_avg(cfs_rq, se);
4275 : update_tg_load_avg(cfs_rq);
4276 : } else if (decayed) {
4277 : cfs_rq_util_change(cfs_rq, 0);
4278 :
4279 : if (flags & UPDATE_TG)
4280 : update_tg_load_avg(cfs_rq);
4281 : }
4282 : }
4283 :
4284 : /*
4285 : * Synchronize entity load avg of dequeued entity without locking
4286 : * the previous rq.
4287 : */
4288 : static void sync_entity_load_avg(struct sched_entity *se)
4289 : {
4290 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
4291 : u64 last_update_time;
4292 :
4293 : last_update_time = cfs_rq_last_update_time(cfs_rq);
4294 : __update_load_avg_blocked_se(last_update_time, se);
4295 : }
4296 :
4297 : /*
4298 : * Task first catches up with cfs_rq, and then subtract
4299 : * itself from the cfs_rq (task must be off the queue now).
4300 : */
4301 : static void remove_entity_load_avg(struct sched_entity *se)
4302 : {
4303 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
4304 : unsigned long flags;
4305 :
4306 : /*
4307 : * tasks cannot exit without having gone through wake_up_new_task() ->
4308 : * enqueue_task_fair() which will have added things to the cfs_rq,
4309 : * so we can remove unconditionally.
4310 : */
4311 :
4312 : sync_entity_load_avg(se);
4313 :
4314 : raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
4315 : ++cfs_rq->removed.nr;
4316 : cfs_rq->removed.util_avg += se->avg.util_avg;
4317 : cfs_rq->removed.load_avg += se->avg.load_avg;
4318 : cfs_rq->removed.runnable_avg += se->avg.runnable_avg;
4319 : raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
4320 : }
4321 :
4322 : static inline unsigned long cfs_rq_runnable_avg(struct cfs_rq *cfs_rq)
4323 : {
4324 : return cfs_rq->avg.runnable_avg;
4325 : }
4326 :
4327 : static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
4328 : {
4329 : return cfs_rq->avg.load_avg;
4330 : }
4331 :
4332 : static int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
4333 :
4334 : static inline unsigned long task_util(struct task_struct *p)
4335 : {
4336 : return READ_ONCE(p->se.avg.util_avg);
4337 : }
4338 :
4339 : static inline unsigned long _task_util_est(struct task_struct *p)
4340 : {
4341 : struct util_est ue = READ_ONCE(p->se.avg.util_est);
4342 :
4343 : return max(ue.ewma, (ue.enqueued & ~UTIL_AVG_UNCHANGED));
4344 : }
4345 :
4346 : static inline unsigned long task_util_est(struct task_struct *p)
4347 : {
4348 : return max(task_util(p), _task_util_est(p));
4349 : }
4350 :
4351 : #ifdef CONFIG_UCLAMP_TASK
4352 : static inline unsigned long uclamp_task_util(struct task_struct *p,
4353 : unsigned long uclamp_min,
4354 : unsigned long uclamp_max)
4355 : {
4356 : return clamp(task_util_est(p), uclamp_min, uclamp_max);
4357 : }
4358 : #else
4359 : static inline unsigned long uclamp_task_util(struct task_struct *p,
4360 : unsigned long uclamp_min,
4361 : unsigned long uclamp_max)
4362 : {
4363 : return task_util_est(p);
4364 : }
4365 : #endif
4366 :
4367 : static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
4368 : struct task_struct *p)
4369 : {
4370 : unsigned int enqueued;
4371 :
4372 : if (!sched_feat(UTIL_EST))
4373 : return;
4374 :
4375 : /* Update root cfs_rq's estimated utilization */
4376 : enqueued = cfs_rq->avg.util_est.enqueued;
4377 : enqueued += _task_util_est(p);
4378 : WRITE_ONCE(cfs_rq->avg.util_est.enqueued, enqueued);
4379 :
4380 : trace_sched_util_est_cfs_tp(cfs_rq);
4381 : }
4382 :
4383 : static inline void util_est_dequeue(struct cfs_rq *cfs_rq,
4384 : struct task_struct *p)
4385 : {
4386 : unsigned int enqueued;
4387 :
4388 : if (!sched_feat(UTIL_EST))
4389 : return;
4390 :
4391 : /* Update root cfs_rq's estimated utilization */
4392 : enqueued = cfs_rq->avg.util_est.enqueued;
4393 : enqueued -= min_t(unsigned int, enqueued, _task_util_est(p));
4394 : WRITE_ONCE(cfs_rq->avg.util_est.enqueued, enqueued);
4395 :
4396 : trace_sched_util_est_cfs_tp(cfs_rq);
4397 : }
4398 :
4399 : #define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
4400 :
4401 : /*
4402 : * Check if a (signed) value is within a specified (unsigned) margin,
4403 : * based on the observation that:
4404 : *
4405 : * abs(x) < y := (unsigned)(x + y - 1) < (2 * y - 1)
4406 : *
4407 : * NOTE: this only works when value + margin < INT_MAX.
4408 : */
4409 : static inline bool within_margin(int value, int margin)
4410 : {
4411 : return ((unsigned int)(value + margin - 1) < (2 * margin - 1));
4412 : }
4413 :
4414 : static inline void util_est_update(struct cfs_rq *cfs_rq,
4415 : struct task_struct *p,
4416 : bool task_sleep)
4417 : {
4418 : long last_ewma_diff, last_enqueued_diff;
4419 : struct util_est ue;
4420 :
4421 : if (!sched_feat(UTIL_EST))
4422 : return;
4423 :
4424 : /*
4425 : * Skip update of task's estimated utilization when the task has not
4426 : * yet completed an activation, e.g. being migrated.
4427 : */
4428 : if (!task_sleep)
4429 : return;
4430 :
4431 : /*
4432 : * If the PELT values haven't changed since enqueue time,
4433 : * skip the util_est update.
4434 : */
4435 : ue = p->se.avg.util_est;
4436 : if (ue.enqueued & UTIL_AVG_UNCHANGED)
4437 : return;
4438 :
4439 : last_enqueued_diff = ue.enqueued;
4440 :
4441 : /*
4442 : * Reset EWMA on utilization increases, the moving average is used only
4443 : * to smooth utilization decreases.
4444 : */
4445 : ue.enqueued = task_util(p);
4446 : if (sched_feat(UTIL_EST_FASTUP)) {
4447 : if (ue.ewma < ue.enqueued) {
4448 : ue.ewma = ue.enqueued;
4449 : goto done;
4450 : }
4451 : }
4452 :
4453 : /*
4454 : * Skip update of task's estimated utilization when its members are
4455 : * already ~1% close to its last activation value.
4456 : */
4457 : last_ewma_diff = ue.enqueued - ue.ewma;
4458 : last_enqueued_diff -= ue.enqueued;
4459 : if (within_margin(last_ewma_diff, UTIL_EST_MARGIN)) {
4460 : if (!within_margin(last_enqueued_diff, UTIL_EST_MARGIN))
4461 : goto done;
4462 :
4463 : return;
4464 : }
4465 :
4466 : /*
4467 : * To avoid overestimation of actual task utilization, skip updates if
4468 : * we cannot grant there is idle time in this CPU.
4469 : */
4470 : if (task_util(p) > capacity_orig_of(cpu_of(rq_of(cfs_rq))))
4471 : return;
4472 :
4473 : /*
4474 : * Update Task's estimated utilization
4475 : *
4476 : * When *p completes an activation we can consolidate another sample
4477 : * of the task size. This is done by storing the current PELT value
4478 : * as ue.enqueued and by using this value to update the Exponential
4479 : * Weighted Moving Average (EWMA):
4480 : *
4481 : * ewma(t) = w * task_util(p) + (1-w) * ewma(t-1)
4482 : * = w * task_util(p) + ewma(t-1) - w * ewma(t-1)
4483 : * = w * (task_util(p) - ewma(t-1)) + ewma(t-1)
4484 : * = w * ( last_ewma_diff ) + ewma(t-1)
4485 : * = w * (last_ewma_diff + ewma(t-1) / w)
4486 : *
4487 : * Where 'w' is the weight of new samples, which is configured to be
4488 : * 0.25, thus making w=1/4 ( >>= UTIL_EST_WEIGHT_SHIFT)
4489 : */
4490 : ue.ewma <<= UTIL_EST_WEIGHT_SHIFT;
4491 : ue.ewma += last_ewma_diff;
4492 : ue.ewma >>= UTIL_EST_WEIGHT_SHIFT;
4493 : done:
4494 : ue.enqueued |= UTIL_AVG_UNCHANGED;
4495 : WRITE_ONCE(p->se.avg.util_est, ue);
4496 :
4497 : trace_sched_util_est_se_tp(&p->se);
4498 : }
4499 :
4500 : static inline int util_fits_cpu(unsigned long util,
4501 : unsigned long uclamp_min,
4502 : unsigned long uclamp_max,
4503 : int cpu)
4504 : {
4505 : unsigned long capacity_orig, capacity_orig_thermal;
4506 : unsigned long capacity = capacity_of(cpu);
4507 : bool fits, uclamp_max_fits;
4508 :
4509 : /*
4510 : * Check if the real util fits without any uclamp boost/cap applied.
4511 : */
4512 : fits = fits_capacity(util, capacity);
4513 :
4514 : if (!uclamp_is_used())
4515 : return fits;
4516 :
4517 : /*
4518 : * We must use capacity_orig_of() for comparing against uclamp_min and
4519 : * uclamp_max. We only care about capacity pressure (by using
4520 : * capacity_of()) for comparing against the real util.
4521 : *
4522 : * If a task is boosted to 1024 for example, we don't want a tiny
4523 : * pressure to skew the check whether it fits a CPU or not.
4524 : *
4525 : * Similarly if a task is capped to capacity_orig_of(little_cpu), it
4526 : * should fit a little cpu even if there's some pressure.
4527 : *
4528 : * Only exception is for thermal pressure since it has a direct impact
4529 : * on available OPP of the system.
4530 : *
4531 : * We honour it for uclamp_min only as a drop in performance level
4532 : * could result in not getting the requested minimum performance level.
4533 : *
4534 : * For uclamp_max, we can tolerate a drop in performance level as the
4535 : * goal is to cap the task. So it's okay if it's getting less.
4536 : */
4537 : capacity_orig = capacity_orig_of(cpu);
4538 : capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu);
4539 :
4540 : /*
4541 : * We want to force a task to fit a cpu as implied by uclamp_max.
4542 : * But we do have some corner cases to cater for..
4543 : *
4544 : *
4545 : * C=z
4546 : * | ___
4547 : * | C=y | |
4548 : * |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
4549 : * | C=x | | | |
4550 : * | ___ | | | |
4551 : * | | | | | | | (util somewhere in this region)
4552 : * | | | | | | |
4553 : * | | | | | | |
4554 : * +----------------------------------------
4555 : * cpu0 cpu1 cpu2
4556 : *
4557 : * In the above example if a task is capped to a specific performance
4558 : * point, y, then when:
4559 : *
4560 : * * util = 80% of x then it does not fit on cpu0 and should migrate
4561 : * to cpu1
4562 : * * util = 80% of y then it is forced to fit on cpu1 to honour
4563 : * uclamp_max request.
4564 : *
4565 : * which is what we're enforcing here. A task always fits if
4566 : * uclamp_max <= capacity_orig. But when uclamp_max > capacity_orig,
4567 : * the normal upmigration rules should withhold still.
4568 : *
4569 : * Only exception is when we are on max capacity, then we need to be
4570 : * careful not to block overutilized state. This is so because:
4571 : *
4572 : * 1. There's no concept of capping at max_capacity! We can't go
4573 : * beyond this performance level anyway.
4574 : * 2. The system is being saturated when we're operating near
4575 : * max capacity, it doesn't make sense to block overutilized.
4576 : */
4577 : uclamp_max_fits = (capacity_orig == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
4578 : uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_orig);
4579 : fits = fits || uclamp_max_fits;
4580 :
4581 : /*
4582 : *
4583 : * C=z
4584 : * | ___ (region a, capped, util >= uclamp_max)
4585 : * | C=y | |
4586 : * |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
4587 : * | C=x | | | |
4588 : * | ___ | | | | (region b, uclamp_min <= util <= uclamp_max)
4589 : * |_ _ _|_ _|_ _ _ _| _ | _ _ _| _ | _ _ _ _ _ uclamp_min
4590 : * | | | | | | |
4591 : * | | | | | | | (region c, boosted, util < uclamp_min)
4592 : * +----------------------------------------
4593 : * cpu0 cpu1 cpu2
4594 : *
4595 : * a) If util > uclamp_max, then we're capped, we don't care about
4596 : * actual fitness value here. We only care if uclamp_max fits
4597 : * capacity without taking margin/pressure into account.
4598 : * See comment above.
4599 : *
4600 : * b) If uclamp_min <= util <= uclamp_max, then the normal
4601 : * fits_capacity() rules apply. Except we need to ensure that we
4602 : * enforce we remain within uclamp_max, see comment above.
4603 : *
4604 : * c) If util < uclamp_min, then we are boosted. Same as (b) but we
4605 : * need to take into account the boosted value fits the CPU without
4606 : * taking margin/pressure into account.
4607 : *
4608 : * Cases (a) and (b) are handled in the 'fits' variable already. We
4609 : * just need to consider an extra check for case (c) after ensuring we
4610 : * handle the case uclamp_min > uclamp_max.
4611 : */
4612 : uclamp_min = min(uclamp_min, uclamp_max);
4613 : if (fits && (util < uclamp_min) && (uclamp_min > capacity_orig_thermal))
4614 : return -1;
4615 :
4616 : return fits;
4617 : }
4618 :
4619 : static inline int task_fits_cpu(struct task_struct *p, int cpu)
4620 : {
4621 : unsigned long uclamp_min = uclamp_eff_value(p, UCLAMP_MIN);
4622 : unsigned long uclamp_max = uclamp_eff_value(p, UCLAMP_MAX);
4623 : unsigned long util = task_util_est(p);
4624 : /*
4625 : * Return true only if the cpu fully fits the task requirements, which
4626 : * include the utilization but also the performance hints.
4627 : */
4628 : return (util_fits_cpu(util, uclamp_min, uclamp_max, cpu) > 0);
4629 : }
4630 :
4631 : static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
4632 : {
4633 : if (!sched_asym_cpucap_active())
4634 : return;
4635 :
4636 : if (!p || p->nr_cpus_allowed == 1) {
4637 : rq->misfit_task_load = 0;
4638 : return;
4639 : }
4640 :
4641 : if (task_fits_cpu(p, cpu_of(rq))) {
4642 : rq->misfit_task_load = 0;
4643 : return;
4644 : }
4645 :
4646 : /*
4647 : * Make sure that misfit_task_load will not be null even if
4648 : * task_h_load() returns 0.
4649 : */
4650 : rq->misfit_task_load = max_t(unsigned long, task_h_load(p), 1);
4651 : }
4652 :
4653 : #else /* CONFIG_SMP */
4654 :
4655 : static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
4656 : {
4657 : return true;
4658 : }
4659 :
4660 : #define UPDATE_TG 0x0
4661 : #define SKIP_AGE_LOAD 0x0
4662 : #define DO_ATTACH 0x0
4663 : #define DO_DETACH 0x0
4664 :
4665 : static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
4666 : {
4667 2069 : cfs_rq_util_change(cfs_rq, 0);
4668 : }
4669 :
4670 : static inline void remove_entity_load_avg(struct sched_entity *se) {}
4671 :
4672 : static inline void
4673 : attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
4674 : static inline void
4675 : detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
4676 :
4677 : static inline int newidle_balance(struct rq *rq, struct rq_flags *rf)
4678 : {
4679 : return 0;
4680 : }
4681 :
4682 : static inline void
4683 : util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
4684 :
4685 : static inline void
4686 : util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
4687 :
4688 : static inline void
4689 : util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p,
4690 : bool task_sleep) {}
4691 : static inline void update_misfit_status(struct task_struct *p, struct rq *rq) {}
4692 :
4693 : #endif /* CONFIG_SMP */
4694 :
4695 : static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
4696 : {
4697 : #ifdef CONFIG_SCHED_DEBUG
4698 : s64 d = se->vruntime - cfs_rq->min_vruntime;
4699 :
4700 : if (d < 0)
4701 : d = -d;
4702 :
4703 : if (d > 3*sysctl_sched_latency)
4704 : schedstat_inc(cfs_rq->nr_spread_over);
4705 : #endif
4706 : }
4707 :
4708 : static inline bool entity_is_long_sleeper(struct sched_entity *se)
4709 : {
4710 : struct cfs_rq *cfs_rq;
4711 : u64 sleep_time;
4712 :
4713 1031 : if (se->exec_start == 0)
4714 : return false;
4715 :
4716 1712 : cfs_rq = cfs_rq_of(se);
4717 :
4718 1712 : sleep_time = rq_clock_task(rq_of(cfs_rq));
4719 :
4720 : /* Happen while migrating because of clock task divergence */
4721 856 : if (sleep_time <= se->exec_start)
4722 : return false;
4723 :
4724 3 : sleep_time -= se->exec_start;
4725 3 : if (sleep_time > ((1ULL << 63) / scale_load_down(NICE_0_LOAD)))
4726 : return true;
4727 :
4728 : return false;
4729 : }
4730 :
4731 : static void
4732 1031 : place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
4733 : {
4734 1031 : u64 vruntime = cfs_rq->min_vruntime;
4735 :
4736 : /*
4737 : * The 'current' period is already promised to the current tasks,
4738 : * however the extra weight of the new task will slow them down a
4739 : * little, place the new task so that it fits in the slot that
4740 : * stays open at the end.
4741 : */
4742 1031 : if (initial && sched_feat(START_DEBIT))
4743 175 : vruntime += sched_vslice(cfs_rq, se);
4744 :
4745 : /* sleeps up to a single latency don't count. */
4746 1031 : if (!initial) {
4747 : unsigned long thresh;
4748 :
4749 856 : if (se_is_idle(se))
4750 : thresh = sysctl_sched_min_granularity;
4751 : else
4752 856 : thresh = sysctl_sched_latency;
4753 :
4754 : /*
4755 : * Halve their sleep time's effect, to allow
4756 : * for a gentler effect of sleepers:
4757 : */
4758 : if (sched_feat(GENTLE_FAIR_SLEEPERS))
4759 856 : thresh >>= 1;
4760 :
4761 856 : vruntime -= thresh;
4762 : }
4763 :
4764 : /*
4765 : * Pull vruntime of the entity being placed to the base level of
4766 : * cfs_rq, to prevent boosting it if placed backwards.
4767 : * However, min_vruntime can advance much faster than real time, with
4768 : * the extreme being when an entity with the minimal weight always runs
4769 : * on the cfs_rq. If the waking entity slept for a long time, its
4770 : * vruntime difference from min_vruntime may overflow s64 and their
4771 : * comparison may get inversed, so ignore the entity's original
4772 : * vruntime in that case.
4773 : * The maximal vruntime speedup is given by the ratio of normal to
4774 : * minimal weight: scale_load_down(NICE_0_LOAD) / MIN_SHARES.
4775 : * When placing a migrated waking entity, its exec_start has been set
4776 : * from a different rq. In order to take into account a possible
4777 : * divergence between new and prev rq's clocks task because of irq and
4778 : * stolen time, we take an additional margin.
4779 : * So, cutting off on the sleep time of
4780 : * 2^63 / scale_load_down(NICE_0_LOAD) ~ 104 days
4781 : * should be safe.
4782 : */
4783 2062 : if (entity_is_long_sleeper(se))
4784 0 : se->vruntime = vruntime;
4785 : else
4786 2062 : se->vruntime = max_vruntime(se->vruntime, vruntime);
4787 1031 : }
4788 :
4789 : static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
4790 :
4791 : static inline bool cfs_bandwidth_used(void);
4792 :
4793 : /*
4794 : * MIGRATION
4795 : *
4796 : * dequeue
4797 : * update_curr()
4798 : * update_min_vruntime()
4799 : * vruntime -= min_vruntime
4800 : *
4801 : * enqueue
4802 : * update_curr()
4803 : * update_min_vruntime()
4804 : * vruntime += min_vruntime
4805 : *
4806 : * this way the vruntime transition between RQs is done when both
4807 : * min_vruntime are up-to-date.
4808 : *
4809 : * WAKEUP (remote)
4810 : *
4811 : * ->migrate_task_rq_fair() (p->state == TASK_WAKING)
4812 : * vruntime -= min_vruntime
4813 : *
4814 : * enqueue
4815 : * update_curr()
4816 : * update_min_vruntime()
4817 : * vruntime += min_vruntime
4818 : *
4819 : * this way we don't have the most up-to-date min_vruntime on the originating
4820 : * CPU and an up-to-date min_vruntime on the destination CPU.
4821 : */
4822 :
4823 : static void
4824 1035 : enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
4825 : {
4826 1035 : bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED);
4827 1035 : bool curr = cfs_rq->curr == se;
4828 :
4829 : /*
4830 : * If we're the current task, we must renormalise before calling
4831 : * update_curr().
4832 : */
4833 1035 : if (renorm && curr)
4834 0 : se->vruntime += cfs_rq->min_vruntime;
4835 :
4836 1035 : update_curr(cfs_rq);
4837 :
4838 : /*
4839 : * Otherwise, renormalise after, such that we're placed at the current
4840 : * moment in time, instead of some random moment in the past. Being
4841 : * placed in the past could significantly boost this task to the
4842 : * fairness detriment of existing tasks.
4843 : */
4844 1035 : if (renorm && !curr)
4845 179 : se->vruntime += cfs_rq->min_vruntime;
4846 :
4847 : /*
4848 : * When enqueuing a sched_entity, we must:
4849 : * - Update loads to have both entity and cfs_rq synced with now.
4850 : * - For group_entity, update its runnable_weight to reflect the new
4851 : * h_nr_running of its group cfs_rq.
4852 : * - For group_entity, update its weight to reflect the new share of
4853 : * its group cfs_rq
4854 : * - Add its new weight to cfs_rq->load.weight
4855 : */
4856 1035 : update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
4857 1035 : se_update_runnable(se);
4858 1035 : update_cfs_group(se);
4859 2070 : account_entity_enqueue(cfs_rq, se);
4860 :
4861 1035 : if (flags & ENQUEUE_WAKEUP)
4862 856 : place_entity(cfs_rq, se, 0);
4863 : /* Entity has migrated, no longer consider this task hot */
4864 : if (flags & ENQUEUE_MIGRATED)
4865 : se->exec_start = 0;
4866 :
4867 : check_schedstat_required();
4868 1035 : update_stats_enqueue_fair(cfs_rq, se, flags);
4869 1035 : check_spread(cfs_rq, se);
4870 1035 : if (!curr)
4871 1035 : __enqueue_entity(cfs_rq, se);
4872 1035 : se->on_rq = 1;
4873 :
4874 : if (cfs_rq->nr_running == 1) {
4875 : check_enqueue_throttle(cfs_rq);
4876 : if (!throttled_hierarchy(cfs_rq))
4877 : list_add_leaf_cfs_rq(cfs_rq);
4878 : }
4879 1035 : }
4880 :
4881 : static void __clear_buddies_last(struct sched_entity *se)
4882 : {
4883 0 : for_each_sched_entity(se) {
4884 0 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
4885 0 : if (cfs_rq->last != se)
4886 : break;
4887 :
4888 0 : cfs_rq->last = NULL;
4889 : }
4890 : }
4891 :
4892 : static void __clear_buddies_next(struct sched_entity *se)
4893 : {
4894 336 : for_each_sched_entity(se) {
4895 672 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
4896 336 : if (cfs_rq->next != se)
4897 : break;
4898 :
4899 336 : cfs_rq->next = NULL;
4900 : }
4901 : }
4902 :
4903 : static void __clear_buddies_skip(struct sched_entity *se)
4904 : {
4905 0 : for_each_sched_entity(se) {
4906 0 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
4907 0 : if (cfs_rq->skip != se)
4908 : break;
4909 :
4910 0 : cfs_rq->skip = NULL;
4911 : }
4912 : }
4913 :
4914 2068 : static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
4915 : {
4916 2068 : if (cfs_rq->last == se)
4917 : __clear_buddies_last(se);
4918 :
4919 2068 : if (cfs_rq->next == se)
4920 : __clear_buddies_next(se);
4921 :
4922 2068 : if (cfs_rq->skip == se)
4923 : __clear_buddies_skip(se);
4924 2068 : }
4925 :
4926 : static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
4927 :
4928 : static void
4929 1033 : dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
4930 : {
4931 1033 : int action = UPDATE_TG;
4932 :
4933 2066 : if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
4934 : action |= DO_DETACH;
4935 :
4936 : /*
4937 : * Update run-time statistics of the 'current'.
4938 : */
4939 1033 : update_curr(cfs_rq);
4940 :
4941 : /*
4942 : * When dequeuing a sched_entity, we must:
4943 : * - Update loads to have both entity and cfs_rq synced with now.
4944 : * - For group_entity, update its runnable_weight to reflect the new
4945 : * h_nr_running of its group cfs_rq.
4946 : * - Subtract its previous weight from cfs_rq->load.weight.
4947 : * - For group entity, update its weight to reflect the new share
4948 : * of its group cfs_rq.
4949 : */
4950 1033 : update_load_avg(cfs_rq, se, action);
4951 1033 : se_update_runnable(se);
4952 :
4953 1033 : update_stats_dequeue_fair(cfs_rq, se, flags);
4954 :
4955 1033 : clear_buddies(cfs_rq, se);
4956 :
4957 1033 : if (se != cfs_rq->curr)
4958 : __dequeue_entity(cfs_rq, se);
4959 1033 : se->on_rq = 0;
4960 2066 : account_entity_dequeue(cfs_rq, se);
4961 :
4962 : /*
4963 : * Normalize after update_curr(); which will also have moved
4964 : * min_vruntime if @se is the one holding it back. But before doing
4965 : * update_min_vruntime() again, which will discount @se's position and
4966 : * can move min_vruntime forward still more.
4967 : */
4968 1033 : if (!(flags & DEQUEUE_SLEEP))
4969 4 : se->vruntime -= cfs_rq->min_vruntime;
4970 :
4971 : /* return excess runtime on last dequeue */
4972 1033 : return_cfs_rq_runtime(cfs_rq);
4973 :
4974 1033 : update_cfs_group(se);
4975 :
4976 : /*
4977 : * Now advance min_vruntime if @se was the entity holding it back,
4978 : * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be
4979 : * put back on, and if we advance min_vruntime, we'll be placed back
4980 : * further than we started -- ie. we'll be penalized.
4981 : */
4982 1033 : if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
4983 1029 : update_min_vruntime(cfs_rq);
4984 :
4985 : if (cfs_rq->nr_running == 0)
4986 : update_idle_cfs_rq_clock_pelt(cfs_rq);
4987 1033 : }
4988 :
4989 : /*
4990 : * Preempt the current task with a newly woken task if needed:
4991 : */
4992 : static void
4993 1 : check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
4994 : {
4995 : unsigned long ideal_runtime, delta_exec;
4996 : struct sched_entity *se;
4997 : s64 delta;
4998 :
4999 : /*
5000 : * When many tasks blow up the sched_period; it is possible that
5001 : * sched_slice() reports unusually large results (when many tasks are
5002 : * very light for example). Therefore impose a maximum.
5003 : */
5004 1 : ideal_runtime = min_t(u64, sched_slice(cfs_rq, curr), sysctl_sched_latency);
5005 :
5006 1 : delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
5007 1 : if (delta_exec > ideal_runtime) {
5008 1 : resched_curr(rq_of(cfs_rq));
5009 : /*
5010 : * The current task ran long enough, ensure it doesn't get
5011 : * re-elected due to buddy favours.
5012 : */
5013 1 : clear_buddies(cfs_rq, curr);
5014 1 : return;
5015 : }
5016 :
5017 : /*
5018 : * Ensure that a task that missed wakeup preemption by a
5019 : * narrow margin doesn't have to wait for a full slice.
5020 : * This also mitigates buddy induced latencies under load.
5021 : */
5022 0 : if (delta_exec < sysctl_sched_min_granularity)
5023 : return;
5024 :
5025 0 : se = __pick_first_entity(cfs_rq);
5026 0 : delta = curr->vruntime - se->vruntime;
5027 :
5028 0 : if (delta < 0)
5029 : return;
5030 :
5031 0 : if (delta > ideal_runtime)
5032 0 : resched_curr(rq_of(cfs_rq));
5033 : }
5034 :
5035 : static void
5036 1034 : set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
5037 : {
5038 1034 : clear_buddies(cfs_rq, se);
5039 :
5040 : /* 'current' is not kept within the tree. */
5041 1034 : if (se->on_rq) {
5042 : /*
5043 : * Any task has to be enqueued before it get to execute on
5044 : * a CPU. So account for the time it spent waiting on the
5045 : * runqueue.
5046 : */
5047 2068 : update_stats_wait_end_fair(cfs_rq, se);
5048 : __dequeue_entity(cfs_rq, se);
5049 : update_load_avg(cfs_rq, se, UPDATE_TG);
5050 : }
5051 :
5052 2068 : update_stats_curr_start(cfs_rq, se);
5053 1034 : cfs_rq->curr = se;
5054 :
5055 : /*
5056 : * Track our maximum slice length, if the CPU's load is at
5057 : * least twice that of our own weight (i.e. dont track it
5058 : * when there are only lesser-weight tasks around):
5059 : */
5060 : if (schedstat_enabled() &&
5061 : rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
5062 : struct sched_statistics *stats;
5063 :
5064 : stats = __schedstats_from_se(se);
5065 : __schedstat_set(stats->slice_max,
5066 : max((u64)stats->slice_max,
5067 : se->sum_exec_runtime - se->prev_sum_exec_runtime));
5068 : }
5069 :
5070 1034 : se->prev_sum_exec_runtime = se->sum_exec_runtime;
5071 1034 : }
5072 :
5073 : static int
5074 : wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
5075 :
5076 : /*
5077 : * Pick the next process, keeping these things in mind, in this order:
5078 : * 1) keep things fair between processes/task groups
5079 : * 2) pick the "next" process, since someone really wants that to run
5080 : * 3) pick the "last" process, for cache locality
5081 : * 4) do not run the "skip" process, if something else is available
5082 : */
5083 : static struct sched_entity *
5084 1030 : pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
5085 : {
5086 1030 : struct sched_entity *left = __pick_first_entity(cfs_rq);
5087 : struct sched_entity *se;
5088 :
5089 : /*
5090 : * If curr is set we have to see if its left of the leftmost entity
5091 : * still in the tree, provided there was anything in the tree at all.
5092 : */
5093 1030 : if (!left || (curr && entity_before(curr, left)))
5094 : left = curr;
5095 :
5096 1030 : se = left; /* ideally we run the leftmost entity */
5097 :
5098 : /*
5099 : * Avoid running the skip buddy, if running something else can
5100 : * be done without getting too unfair.
5101 : */
5102 1030 : if (cfs_rq->skip && cfs_rq->skip == se) {
5103 : struct sched_entity *second;
5104 :
5105 0 : if (se == curr) {
5106 : second = __pick_first_entity(cfs_rq);
5107 : } else {
5108 0 : second = __pick_next_entity(se);
5109 0 : if (!second || (curr && entity_before(curr, second)))
5110 : second = curr;
5111 : }
5112 :
5113 0 : if (second && wakeup_preempt_entity(second, left) < 1)
5114 0 : se = second;
5115 : }
5116 :
5117 1030 : if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) {
5118 : /*
5119 : * Someone really wants this to run. If it's not unfair, run it.
5120 : */
5121 336 : se = cfs_rq->next;
5122 694 : } else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) {
5123 : /*
5124 : * Prefer last buddy, try to return the CPU to a preempted task.
5125 : */
5126 0 : se = cfs_rq->last;
5127 : }
5128 :
5129 1030 : return se;
5130 : }
5131 :
5132 : static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
5133 :
5134 1033 : static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
5135 : {
5136 : /*
5137 : * If still on the runqueue then deactivate_task()
5138 : * was not called and update_curr() has to be done:
5139 : */
5140 1033 : if (prev->on_rq)
5141 0 : update_curr(cfs_rq);
5142 :
5143 : /* throttle cfs_rqs exceeding runtime */
5144 1033 : check_cfs_rq_runtime(cfs_rq);
5145 :
5146 1033 : check_spread(cfs_rq, prev);
5147 :
5148 1033 : if (prev->on_rq) {
5149 0 : update_stats_wait_start_fair(cfs_rq, prev);
5150 : /* Put 'current' back into the tree. */
5151 0 : __enqueue_entity(cfs_rq, prev);
5152 : /* in !on_rq case, update occurred at dequeue */
5153 0 : update_load_avg(cfs_rq, prev, 0);
5154 : }
5155 1033 : cfs_rq->curr = NULL;
5156 1033 : }
5157 :
5158 : static void
5159 1 : entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
5160 : {
5161 : /*
5162 : * Update run-time statistics of the 'current'.
5163 : */
5164 1 : update_curr(cfs_rq);
5165 :
5166 : /*
5167 : * Ensure that runnable average is periodically updated.
5168 : */
5169 1 : update_load_avg(cfs_rq, curr, UPDATE_TG);
5170 1 : update_cfs_group(curr);
5171 :
5172 : #ifdef CONFIG_SCHED_HRTICK
5173 : /*
5174 : * queued ticks are scheduled to match the slice, so don't bother
5175 : * validating it and just reschedule.
5176 : */
5177 : if (queued) {
5178 : resched_curr(rq_of(cfs_rq));
5179 : return;
5180 : }
5181 : /*
5182 : * don't let the period tick interfere with the hrtick preemption
5183 : */
5184 : if (!sched_feat(DOUBLE_TICK) &&
5185 : hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
5186 : return;
5187 : #endif
5188 :
5189 1 : if (cfs_rq->nr_running > 1)
5190 1 : check_preempt_tick(cfs_rq, curr);
5191 1 : }
5192 :
5193 :
5194 : /**************************************************
5195 : * CFS bandwidth control machinery
5196 : */
5197 :
5198 : #ifdef CONFIG_CFS_BANDWIDTH
5199 :
5200 : #ifdef CONFIG_JUMP_LABEL
5201 : static struct static_key __cfs_bandwidth_used;
5202 :
5203 : static inline bool cfs_bandwidth_used(void)
5204 : {
5205 : return static_key_false(&__cfs_bandwidth_used);
5206 : }
5207 :
5208 : void cfs_bandwidth_usage_inc(void)
5209 : {
5210 : static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used);
5211 : }
5212 :
5213 : void cfs_bandwidth_usage_dec(void)
5214 : {
5215 : static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
5216 : }
5217 : #else /* CONFIG_JUMP_LABEL */
5218 : static bool cfs_bandwidth_used(void)
5219 : {
5220 : return true;
5221 : }
5222 :
5223 : void cfs_bandwidth_usage_inc(void) {}
5224 : void cfs_bandwidth_usage_dec(void) {}
5225 : #endif /* CONFIG_JUMP_LABEL */
5226 :
5227 : /*
5228 : * default period for cfs group bandwidth.
5229 : * default: 0.1s, units: nanoseconds
5230 : */
5231 : static inline u64 default_cfs_period(void)
5232 : {
5233 : return 100000000ULL;
5234 : }
5235 :
5236 : static inline u64 sched_cfs_bandwidth_slice(void)
5237 : {
5238 : return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
5239 : }
5240 :
5241 : /*
5242 : * Replenish runtime according to assigned quota. We use sched_clock_cpu
5243 : * directly instead of rq->clock to avoid adding additional synchronization
5244 : * around rq->lock.
5245 : *
5246 : * requires cfs_b->lock
5247 : */
5248 : void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
5249 : {
5250 : s64 runtime;
5251 :
5252 : if (unlikely(cfs_b->quota == RUNTIME_INF))
5253 : return;
5254 :
5255 : cfs_b->runtime += cfs_b->quota;
5256 : runtime = cfs_b->runtime_snap - cfs_b->runtime;
5257 : if (runtime > 0) {
5258 : cfs_b->burst_time += runtime;
5259 : cfs_b->nr_burst++;
5260 : }
5261 :
5262 : cfs_b->runtime = min(cfs_b->runtime, cfs_b->quota + cfs_b->burst);
5263 : cfs_b->runtime_snap = cfs_b->runtime;
5264 : }
5265 :
5266 : static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
5267 : {
5268 : return &tg->cfs_bandwidth;
5269 : }
5270 :
5271 : /* returns 0 on failure to allocate runtime */
5272 : static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
5273 : struct cfs_rq *cfs_rq, u64 target_runtime)
5274 : {
5275 : u64 min_amount, amount = 0;
5276 :
5277 : lockdep_assert_held(&cfs_b->lock);
5278 :
5279 : /* note: this is a positive sum as runtime_remaining <= 0 */
5280 : min_amount = target_runtime - cfs_rq->runtime_remaining;
5281 :
5282 : if (cfs_b->quota == RUNTIME_INF)
5283 : amount = min_amount;
5284 : else {
5285 : start_cfs_bandwidth(cfs_b);
5286 :
5287 : if (cfs_b->runtime > 0) {
5288 : amount = min(cfs_b->runtime, min_amount);
5289 : cfs_b->runtime -= amount;
5290 : cfs_b->idle = 0;
5291 : }
5292 : }
5293 :
5294 : cfs_rq->runtime_remaining += amount;
5295 :
5296 : return cfs_rq->runtime_remaining > 0;
5297 : }
5298 :
5299 : /* returns 0 on failure to allocate runtime */
5300 : static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
5301 : {
5302 : struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5303 : int ret;
5304 :
5305 : raw_spin_lock(&cfs_b->lock);
5306 : ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
5307 : raw_spin_unlock(&cfs_b->lock);
5308 :
5309 : return ret;
5310 : }
5311 :
5312 : static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
5313 : {
5314 : /* dock delta_exec before expiring quota (as it could span periods) */
5315 : cfs_rq->runtime_remaining -= delta_exec;
5316 :
5317 : if (likely(cfs_rq->runtime_remaining > 0))
5318 : return;
5319 :
5320 : if (cfs_rq->throttled)
5321 : return;
5322 : /*
5323 : * if we're unable to extend our runtime we resched so that the active
5324 : * hierarchy can be throttled
5325 : */
5326 : if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
5327 : resched_curr(rq_of(cfs_rq));
5328 : }
5329 :
5330 : static __always_inline
5331 : void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
5332 : {
5333 : if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
5334 : return;
5335 :
5336 : __account_cfs_rq_runtime(cfs_rq, delta_exec);
5337 : }
5338 :
5339 : static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
5340 : {
5341 : return cfs_bandwidth_used() && cfs_rq->throttled;
5342 : }
5343 :
5344 : /* check whether cfs_rq, or any parent, is throttled */
5345 : static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
5346 : {
5347 : return cfs_bandwidth_used() && cfs_rq->throttle_count;
5348 : }
5349 :
5350 : /*
5351 : * Ensure that neither of the group entities corresponding to src_cpu or
5352 : * dest_cpu are members of a throttled hierarchy when performing group
5353 : * load-balance operations.
5354 : */
5355 : static inline int throttled_lb_pair(struct task_group *tg,
5356 : int src_cpu, int dest_cpu)
5357 : {
5358 : struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
5359 :
5360 : src_cfs_rq = tg->cfs_rq[src_cpu];
5361 : dest_cfs_rq = tg->cfs_rq[dest_cpu];
5362 :
5363 : return throttled_hierarchy(src_cfs_rq) ||
5364 : throttled_hierarchy(dest_cfs_rq);
5365 : }
5366 :
5367 : static int tg_unthrottle_up(struct task_group *tg, void *data)
5368 : {
5369 : struct rq *rq = data;
5370 : struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
5371 :
5372 : cfs_rq->throttle_count--;
5373 : if (!cfs_rq->throttle_count) {
5374 : cfs_rq->throttled_clock_pelt_time += rq_clock_pelt(rq) -
5375 : cfs_rq->throttled_clock_pelt;
5376 :
5377 : /* Add cfs_rq with load or one or more already running entities to the list */
5378 : if (!cfs_rq_is_decayed(cfs_rq))
5379 : list_add_leaf_cfs_rq(cfs_rq);
5380 : }
5381 :
5382 : return 0;
5383 : }
5384 :
5385 : static int tg_throttle_down(struct task_group *tg, void *data)
5386 : {
5387 : struct rq *rq = data;
5388 : struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
5389 :
5390 : /* group is entering throttled state, stop time */
5391 : if (!cfs_rq->throttle_count) {
5392 : cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
5393 : list_del_leaf_cfs_rq(cfs_rq);
5394 : }
5395 : cfs_rq->throttle_count++;
5396 :
5397 : return 0;
5398 : }
5399 :
5400 : static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
5401 : {
5402 : struct rq *rq = rq_of(cfs_rq);
5403 : struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5404 : struct sched_entity *se;
5405 : long task_delta, idle_task_delta, dequeue = 1;
5406 :
5407 : raw_spin_lock(&cfs_b->lock);
5408 : /* This will start the period timer if necessary */
5409 : if (__assign_cfs_rq_runtime(cfs_b, cfs_rq, 1)) {
5410 : /*
5411 : * We have raced with bandwidth becoming available, and if we
5412 : * actually throttled the timer might not unthrottle us for an
5413 : * entire period. We additionally needed to make sure that any
5414 : * subsequent check_cfs_rq_runtime calls agree not to throttle
5415 : * us, as we may commit to do cfs put_prev+pick_next, so we ask
5416 : * for 1ns of runtime rather than just check cfs_b.
5417 : */
5418 : dequeue = 0;
5419 : } else {
5420 : list_add_tail_rcu(&cfs_rq->throttled_list,
5421 : &cfs_b->throttled_cfs_rq);
5422 : }
5423 : raw_spin_unlock(&cfs_b->lock);
5424 :
5425 : if (!dequeue)
5426 : return false; /* Throttle no longer required. */
5427 :
5428 : se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
5429 :
5430 : /* freeze hierarchy runnable averages while throttled */
5431 : rcu_read_lock();
5432 : walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
5433 : rcu_read_unlock();
5434 :
5435 : task_delta = cfs_rq->h_nr_running;
5436 : idle_task_delta = cfs_rq->idle_h_nr_running;
5437 : for_each_sched_entity(se) {
5438 : struct cfs_rq *qcfs_rq = cfs_rq_of(se);
5439 : /* throttled entity or throttle-on-deactivate */
5440 : if (!se->on_rq)
5441 : goto done;
5442 :
5443 : dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
5444 :
5445 : if (cfs_rq_is_idle(group_cfs_rq(se)))
5446 : idle_task_delta = cfs_rq->h_nr_running;
5447 :
5448 : qcfs_rq->h_nr_running -= task_delta;
5449 : qcfs_rq->idle_h_nr_running -= idle_task_delta;
5450 :
5451 : if (qcfs_rq->load.weight) {
5452 : /* Avoid re-evaluating load for this entity: */
5453 : se = parent_entity(se);
5454 : break;
5455 : }
5456 : }
5457 :
5458 : for_each_sched_entity(se) {
5459 : struct cfs_rq *qcfs_rq = cfs_rq_of(se);
5460 : /* throttled entity or throttle-on-deactivate */
5461 : if (!se->on_rq)
5462 : goto done;
5463 :
5464 : update_load_avg(qcfs_rq, se, 0);
5465 : se_update_runnable(se);
5466 :
5467 : if (cfs_rq_is_idle(group_cfs_rq(se)))
5468 : idle_task_delta = cfs_rq->h_nr_running;
5469 :
5470 : qcfs_rq->h_nr_running -= task_delta;
5471 : qcfs_rq->idle_h_nr_running -= idle_task_delta;
5472 : }
5473 :
5474 : /* At this point se is NULL and we are at root level*/
5475 : sub_nr_running(rq, task_delta);
5476 :
5477 : done:
5478 : /*
5479 : * Note: distribution will already see us throttled via the
5480 : * throttled-list. rq->lock protects completion.
5481 : */
5482 : cfs_rq->throttled = 1;
5483 : cfs_rq->throttled_clock = rq_clock(rq);
5484 : return true;
5485 : }
5486 :
5487 : void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
5488 : {
5489 : struct rq *rq = rq_of(cfs_rq);
5490 : struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5491 : struct sched_entity *se;
5492 : long task_delta, idle_task_delta;
5493 :
5494 : se = cfs_rq->tg->se[cpu_of(rq)];
5495 :
5496 : cfs_rq->throttled = 0;
5497 :
5498 : update_rq_clock(rq);
5499 :
5500 : raw_spin_lock(&cfs_b->lock);
5501 : cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
5502 : list_del_rcu(&cfs_rq->throttled_list);
5503 : raw_spin_unlock(&cfs_b->lock);
5504 :
5505 : /* update hierarchical throttle state */
5506 : walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
5507 :
5508 : if (!cfs_rq->load.weight) {
5509 : if (!cfs_rq->on_list)
5510 : return;
5511 : /*
5512 : * Nothing to run but something to decay (on_list)?
5513 : * Complete the branch.
5514 : */
5515 : for_each_sched_entity(se) {
5516 : if (list_add_leaf_cfs_rq(cfs_rq_of(se)))
5517 : break;
5518 : }
5519 : goto unthrottle_throttle;
5520 : }
5521 :
5522 : task_delta = cfs_rq->h_nr_running;
5523 : idle_task_delta = cfs_rq->idle_h_nr_running;
5524 : for_each_sched_entity(se) {
5525 : struct cfs_rq *qcfs_rq = cfs_rq_of(se);
5526 :
5527 : if (se->on_rq)
5528 : break;
5529 : enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP);
5530 :
5531 : if (cfs_rq_is_idle(group_cfs_rq(se)))
5532 : idle_task_delta = cfs_rq->h_nr_running;
5533 :
5534 : qcfs_rq->h_nr_running += task_delta;
5535 : qcfs_rq->idle_h_nr_running += idle_task_delta;
5536 :
5537 : /* end evaluation on encountering a throttled cfs_rq */
5538 : if (cfs_rq_throttled(qcfs_rq))
5539 : goto unthrottle_throttle;
5540 : }
5541 :
5542 : for_each_sched_entity(se) {
5543 : struct cfs_rq *qcfs_rq = cfs_rq_of(se);
5544 :
5545 : update_load_avg(qcfs_rq, se, UPDATE_TG);
5546 : se_update_runnable(se);
5547 :
5548 : if (cfs_rq_is_idle(group_cfs_rq(se)))
5549 : idle_task_delta = cfs_rq->h_nr_running;
5550 :
5551 : qcfs_rq->h_nr_running += task_delta;
5552 : qcfs_rq->idle_h_nr_running += idle_task_delta;
5553 :
5554 : /* end evaluation on encountering a throttled cfs_rq */
5555 : if (cfs_rq_throttled(qcfs_rq))
5556 : goto unthrottle_throttle;
5557 : }
5558 :
5559 : /* At this point se is NULL and we are at root level*/
5560 : add_nr_running(rq, task_delta);
5561 :
5562 : unthrottle_throttle:
5563 : assert_list_leaf_cfs_rq(rq);
5564 :
5565 : /* Determine whether we need to wake up potentially idle CPU: */
5566 : if (rq->curr == rq->idle && rq->cfs.nr_running)
5567 : resched_curr(rq);
5568 : }
5569 :
5570 : #ifdef CONFIG_SMP
5571 : static void __cfsb_csd_unthrottle(void *arg)
5572 : {
5573 : struct cfs_rq *cursor, *tmp;
5574 : struct rq *rq = arg;
5575 : struct rq_flags rf;
5576 :
5577 : rq_lock(rq, &rf);
5578 :
5579 : /*
5580 : * Iterating over the list can trigger several call to
5581 : * update_rq_clock() in unthrottle_cfs_rq().
5582 : * Do it once and skip the potential next ones.
5583 : */
5584 : update_rq_clock(rq);
5585 : rq_clock_start_loop_update(rq);
5586 :
5587 : /*
5588 : * Since we hold rq lock we're safe from concurrent manipulation of
5589 : * the CSD list. However, this RCU critical section annotates the
5590 : * fact that we pair with sched_free_group_rcu(), so that we cannot
5591 : * race with group being freed in the window between removing it
5592 : * from the list and advancing to the next entry in the list.
5593 : */
5594 : rcu_read_lock();
5595 :
5596 : list_for_each_entry_safe(cursor, tmp, &rq->cfsb_csd_list,
5597 : throttled_csd_list) {
5598 : list_del_init(&cursor->throttled_csd_list);
5599 :
5600 : if (cfs_rq_throttled(cursor))
5601 : unthrottle_cfs_rq(cursor);
5602 : }
5603 :
5604 : rcu_read_unlock();
5605 :
5606 : rq_clock_stop_loop_update(rq);
5607 : rq_unlock(rq, &rf);
5608 : }
5609 :
5610 : static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
5611 : {
5612 : struct rq *rq = rq_of(cfs_rq);
5613 : bool first;
5614 :
5615 : if (rq == this_rq()) {
5616 : unthrottle_cfs_rq(cfs_rq);
5617 : return;
5618 : }
5619 :
5620 : /* Already enqueued */
5621 : if (SCHED_WARN_ON(!list_empty(&cfs_rq->throttled_csd_list)))
5622 : return;
5623 :
5624 : first = list_empty(&rq->cfsb_csd_list);
5625 : list_add_tail(&cfs_rq->throttled_csd_list, &rq->cfsb_csd_list);
5626 : if (first)
5627 : smp_call_function_single_async(cpu_of(rq), &rq->cfsb_csd);
5628 : }
5629 : #else
5630 : static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
5631 : {
5632 : unthrottle_cfs_rq(cfs_rq);
5633 : }
5634 : #endif
5635 :
5636 : static void unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
5637 : {
5638 : lockdep_assert_rq_held(rq_of(cfs_rq));
5639 :
5640 : if (SCHED_WARN_ON(!cfs_rq_throttled(cfs_rq) ||
5641 : cfs_rq->runtime_remaining <= 0))
5642 : return;
5643 :
5644 : __unthrottle_cfs_rq_async(cfs_rq);
5645 : }
5646 :
5647 : static bool distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
5648 : {
5649 : struct cfs_rq *local_unthrottle = NULL;
5650 : int this_cpu = smp_processor_id();
5651 : u64 runtime, remaining = 1;
5652 : bool throttled = false;
5653 : struct cfs_rq *cfs_rq;
5654 : struct rq_flags rf;
5655 : struct rq *rq;
5656 :
5657 : rcu_read_lock();
5658 : list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
5659 : throttled_list) {
5660 : rq = rq_of(cfs_rq);
5661 :
5662 : if (!remaining) {
5663 : throttled = true;
5664 : break;
5665 : }
5666 :
5667 : rq_lock_irqsave(rq, &rf);
5668 : if (!cfs_rq_throttled(cfs_rq))
5669 : goto next;
5670 :
5671 : #ifdef CONFIG_SMP
5672 : /* Already queued for async unthrottle */
5673 : if (!list_empty(&cfs_rq->throttled_csd_list))
5674 : goto next;
5675 : #endif
5676 :
5677 : /* By the above checks, this should never be true */
5678 : SCHED_WARN_ON(cfs_rq->runtime_remaining > 0);
5679 :
5680 : raw_spin_lock(&cfs_b->lock);
5681 : runtime = -cfs_rq->runtime_remaining + 1;
5682 : if (runtime > cfs_b->runtime)
5683 : runtime = cfs_b->runtime;
5684 : cfs_b->runtime -= runtime;
5685 : remaining = cfs_b->runtime;
5686 : raw_spin_unlock(&cfs_b->lock);
5687 :
5688 : cfs_rq->runtime_remaining += runtime;
5689 :
5690 : /* we check whether we're throttled above */
5691 : if (cfs_rq->runtime_remaining > 0) {
5692 : if (cpu_of(rq) != this_cpu ||
5693 : SCHED_WARN_ON(local_unthrottle))
5694 : unthrottle_cfs_rq_async(cfs_rq);
5695 : else
5696 : local_unthrottle = cfs_rq;
5697 : } else {
5698 : throttled = true;
5699 : }
5700 :
5701 : next:
5702 : rq_unlock_irqrestore(rq, &rf);
5703 : }
5704 : rcu_read_unlock();
5705 :
5706 : if (local_unthrottle) {
5707 : rq = cpu_rq(this_cpu);
5708 : rq_lock_irqsave(rq, &rf);
5709 : if (cfs_rq_throttled(local_unthrottle))
5710 : unthrottle_cfs_rq(local_unthrottle);
5711 : rq_unlock_irqrestore(rq, &rf);
5712 : }
5713 :
5714 : return throttled;
5715 : }
5716 :
5717 : /*
5718 : * Responsible for refilling a task_group's bandwidth and unthrottling its
5719 : * cfs_rqs as appropriate. If there has been no activity within the last
5720 : * period the timer is deactivated until scheduling resumes; cfs_b->idle is
5721 : * used to track this state.
5722 : */
5723 : static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
5724 : {
5725 : int throttled;
5726 :
5727 : /* no need to continue the timer with no bandwidth constraint */
5728 : if (cfs_b->quota == RUNTIME_INF)
5729 : goto out_deactivate;
5730 :
5731 : throttled = !list_empty(&cfs_b->throttled_cfs_rq);
5732 : cfs_b->nr_periods += overrun;
5733 :
5734 : /* Refill extra burst quota even if cfs_b->idle */
5735 : __refill_cfs_bandwidth_runtime(cfs_b);
5736 :
5737 : /*
5738 : * idle depends on !throttled (for the case of a large deficit), and if
5739 : * we're going inactive then everything else can be deferred
5740 : */
5741 : if (cfs_b->idle && !throttled)
5742 : goto out_deactivate;
5743 :
5744 : if (!throttled) {
5745 : /* mark as potentially idle for the upcoming period */
5746 : cfs_b->idle = 1;
5747 : return 0;
5748 : }
5749 :
5750 : /* account preceding periods in which throttling occurred */
5751 : cfs_b->nr_throttled += overrun;
5752 :
5753 : /*
5754 : * This check is repeated as we release cfs_b->lock while we unthrottle.
5755 : */
5756 : while (throttled && cfs_b->runtime > 0) {
5757 : raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
5758 : /* we can't nest cfs_b->lock while distributing bandwidth */
5759 : throttled = distribute_cfs_runtime(cfs_b);
5760 : raw_spin_lock_irqsave(&cfs_b->lock, flags);
5761 : }
5762 :
5763 : /*
5764 : * While we are ensured activity in the period following an
5765 : * unthrottle, this also covers the case in which the new bandwidth is
5766 : * insufficient to cover the existing bandwidth deficit. (Forcing the
5767 : * timer to remain active while there are any throttled entities.)
5768 : */
5769 : cfs_b->idle = 0;
5770 :
5771 : return 0;
5772 :
5773 : out_deactivate:
5774 : return 1;
5775 : }
5776 :
5777 : /* a cfs_rq won't donate quota below this amount */
5778 : static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
5779 : /* minimum remaining period time to redistribute slack quota */
5780 : static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
5781 : /* how long we wait to gather additional slack before distributing */
5782 : static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
5783 :
5784 : /*
5785 : * Are we near the end of the current quota period?
5786 : *
5787 : * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
5788 : * hrtimer base being cleared by hrtimer_start. In the case of
5789 : * migrate_hrtimers, base is never cleared, so we are fine.
5790 : */
5791 : static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
5792 : {
5793 : struct hrtimer *refresh_timer = &cfs_b->period_timer;
5794 : s64 remaining;
5795 :
5796 : /* if the call-back is running a quota refresh is already occurring */
5797 : if (hrtimer_callback_running(refresh_timer))
5798 : return 1;
5799 :
5800 : /* is a quota refresh about to occur? */
5801 : remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
5802 : if (remaining < (s64)min_expire)
5803 : return 1;
5804 :
5805 : return 0;
5806 : }
5807 :
5808 : static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
5809 : {
5810 : u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
5811 :
5812 : /* if there's a quota refresh soon don't bother with slack */
5813 : if (runtime_refresh_within(cfs_b, min_left))
5814 : return;
5815 :
5816 : /* don't push forwards an existing deferred unthrottle */
5817 : if (cfs_b->slack_started)
5818 : return;
5819 : cfs_b->slack_started = true;
5820 :
5821 : hrtimer_start(&cfs_b->slack_timer,
5822 : ns_to_ktime(cfs_bandwidth_slack_period),
5823 : HRTIMER_MODE_REL);
5824 : }
5825 :
5826 : /* we know any runtime found here is valid as update_curr() precedes return */
5827 : static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
5828 : {
5829 : struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
5830 : s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
5831 :
5832 : if (slack_runtime <= 0)
5833 : return;
5834 :
5835 : raw_spin_lock(&cfs_b->lock);
5836 : if (cfs_b->quota != RUNTIME_INF) {
5837 : cfs_b->runtime += slack_runtime;
5838 :
5839 : /* we are under rq->lock, defer unthrottling using a timer */
5840 : if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
5841 : !list_empty(&cfs_b->throttled_cfs_rq))
5842 : start_cfs_slack_bandwidth(cfs_b);
5843 : }
5844 : raw_spin_unlock(&cfs_b->lock);
5845 :
5846 : /* even if it's not valid for return we don't want to try again */
5847 : cfs_rq->runtime_remaining -= slack_runtime;
5848 : }
5849 :
5850 : static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
5851 : {
5852 : if (!cfs_bandwidth_used())
5853 : return;
5854 :
5855 : if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
5856 : return;
5857 :
5858 : __return_cfs_rq_runtime(cfs_rq);
5859 : }
5860 :
5861 : /*
5862 : * This is done with a timer (instead of inline with bandwidth return) since
5863 : * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
5864 : */
5865 : static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
5866 : {
5867 : u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
5868 : unsigned long flags;
5869 :
5870 : /* confirm we're still not at a refresh boundary */
5871 : raw_spin_lock_irqsave(&cfs_b->lock, flags);
5872 : cfs_b->slack_started = false;
5873 :
5874 : if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
5875 : raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
5876 : return;
5877 : }
5878 :
5879 : if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
5880 : runtime = cfs_b->runtime;
5881 :
5882 : raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
5883 :
5884 : if (!runtime)
5885 : return;
5886 :
5887 : distribute_cfs_runtime(cfs_b);
5888 : }
5889 :
5890 : /*
5891 : * When a group wakes up we want to make sure that its quota is not already
5892 : * expired/exceeded, otherwise it may be allowed to steal additional ticks of
5893 : * runtime as update_curr() throttling can not trigger until it's on-rq.
5894 : */
5895 : static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
5896 : {
5897 : if (!cfs_bandwidth_used())
5898 : return;
5899 :
5900 : /* an active group must be handled by the update_curr()->put() path */
5901 : if (!cfs_rq->runtime_enabled || cfs_rq->curr)
5902 : return;
5903 :
5904 : /* ensure the group is not already throttled */
5905 : if (cfs_rq_throttled(cfs_rq))
5906 : return;
5907 :
5908 : /* update runtime allocation */
5909 : account_cfs_rq_runtime(cfs_rq, 0);
5910 : if (cfs_rq->runtime_remaining <= 0)
5911 : throttle_cfs_rq(cfs_rq);
5912 : }
5913 :
5914 : static void sync_throttle(struct task_group *tg, int cpu)
5915 : {
5916 : struct cfs_rq *pcfs_rq, *cfs_rq;
5917 :
5918 : if (!cfs_bandwidth_used())
5919 : return;
5920 :
5921 : if (!tg->parent)
5922 : return;
5923 :
5924 : cfs_rq = tg->cfs_rq[cpu];
5925 : pcfs_rq = tg->parent->cfs_rq[cpu];
5926 :
5927 : cfs_rq->throttle_count = pcfs_rq->throttle_count;
5928 : cfs_rq->throttled_clock_pelt = rq_clock_pelt(cpu_rq(cpu));
5929 : }
5930 :
5931 : /* conditionally throttle active cfs_rq's from put_prev_entity() */
5932 : static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
5933 : {
5934 : if (!cfs_bandwidth_used())
5935 : return false;
5936 :
5937 : if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
5938 : return false;
5939 :
5940 : /*
5941 : * it's possible for a throttled entity to be forced into a running
5942 : * state (e.g. set_curr_task), in this case we're finished.
5943 : */
5944 : if (cfs_rq_throttled(cfs_rq))
5945 : return true;
5946 :
5947 : return throttle_cfs_rq(cfs_rq);
5948 : }
5949 :
5950 : static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
5951 : {
5952 : struct cfs_bandwidth *cfs_b =
5953 : container_of(timer, struct cfs_bandwidth, slack_timer);
5954 :
5955 : do_sched_cfs_slack_timer(cfs_b);
5956 :
5957 : return HRTIMER_NORESTART;
5958 : }
5959 :
5960 : extern const u64 max_cfs_quota_period;
5961 :
5962 : static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
5963 : {
5964 : struct cfs_bandwidth *cfs_b =
5965 : container_of(timer, struct cfs_bandwidth, period_timer);
5966 : unsigned long flags;
5967 : int overrun;
5968 : int idle = 0;
5969 : int count = 0;
5970 :
5971 : raw_spin_lock_irqsave(&cfs_b->lock, flags);
5972 : for (;;) {
5973 : overrun = hrtimer_forward_now(timer, cfs_b->period);
5974 : if (!overrun)
5975 : break;
5976 :
5977 : idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
5978 :
5979 : if (++count > 3) {
5980 : u64 new, old = ktime_to_ns(cfs_b->period);
5981 :
5982 : /*
5983 : * Grow period by a factor of 2 to avoid losing precision.
5984 : * Precision loss in the quota/period ratio can cause __cfs_schedulable
5985 : * to fail.
5986 : */
5987 : new = old * 2;
5988 : if (new < max_cfs_quota_period) {
5989 : cfs_b->period = ns_to_ktime(new);
5990 : cfs_b->quota *= 2;
5991 : cfs_b->burst *= 2;
5992 :
5993 : pr_warn_ratelimited(
5994 : "cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n",
5995 : smp_processor_id(),
5996 : div_u64(new, NSEC_PER_USEC),
5997 : div_u64(cfs_b->quota, NSEC_PER_USEC));
5998 : } else {
5999 : pr_warn_ratelimited(
6000 : "cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n",
6001 : smp_processor_id(),
6002 : div_u64(old, NSEC_PER_USEC),
6003 : div_u64(cfs_b->quota, NSEC_PER_USEC));
6004 : }
6005 :
6006 : /* reset count so we don't come right back in here */
6007 : count = 0;
6008 : }
6009 : }
6010 : if (idle)
6011 : cfs_b->period_active = 0;
6012 : raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
6013 :
6014 : return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
6015 : }
6016 :
6017 : void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
6018 : {
6019 : raw_spin_lock_init(&cfs_b->lock);
6020 : cfs_b->runtime = 0;
6021 : cfs_b->quota = RUNTIME_INF;
6022 : cfs_b->period = ns_to_ktime(default_cfs_period());
6023 : cfs_b->burst = 0;
6024 :
6025 : INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
6026 : hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
6027 : cfs_b->period_timer.function = sched_cfs_period_timer;
6028 :
6029 : /* Add a random offset so that timers interleave */
6030 : hrtimer_set_expires(&cfs_b->period_timer,
6031 : get_random_u32_below(cfs_b->period));
6032 : hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
6033 : cfs_b->slack_timer.function = sched_cfs_slack_timer;
6034 : cfs_b->slack_started = false;
6035 : }
6036 :
6037 : static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
6038 : {
6039 : cfs_rq->runtime_enabled = 0;
6040 : INIT_LIST_HEAD(&cfs_rq->throttled_list);
6041 : #ifdef CONFIG_SMP
6042 : INIT_LIST_HEAD(&cfs_rq->throttled_csd_list);
6043 : #endif
6044 : }
6045 :
6046 : void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
6047 : {
6048 : lockdep_assert_held(&cfs_b->lock);
6049 :
6050 : if (cfs_b->period_active)
6051 : return;
6052 :
6053 : cfs_b->period_active = 1;
6054 : hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period);
6055 : hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED);
6056 : }
6057 :
6058 : static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
6059 : {
6060 : int __maybe_unused i;
6061 :
6062 : /* init_cfs_bandwidth() was not called */
6063 : if (!cfs_b->throttled_cfs_rq.next)
6064 : return;
6065 :
6066 : hrtimer_cancel(&cfs_b->period_timer);
6067 : hrtimer_cancel(&cfs_b->slack_timer);
6068 :
6069 : /*
6070 : * It is possible that we still have some cfs_rq's pending on a CSD
6071 : * list, though this race is very rare. In order for this to occur, we
6072 : * must have raced with the last task leaving the group while there
6073 : * exist throttled cfs_rq(s), and the period_timer must have queued the
6074 : * CSD item but the remote cpu has not yet processed it. To handle this,
6075 : * we can simply flush all pending CSD work inline here. We're
6076 : * guaranteed at this point that no additional cfs_rq of this group can
6077 : * join a CSD list.
6078 : */
6079 : #ifdef CONFIG_SMP
6080 : for_each_possible_cpu(i) {
6081 : struct rq *rq = cpu_rq(i);
6082 : unsigned long flags;
6083 :
6084 : if (list_empty(&rq->cfsb_csd_list))
6085 : continue;
6086 :
6087 : local_irq_save(flags);
6088 : __cfsb_csd_unthrottle(rq);
6089 : local_irq_restore(flags);
6090 : }
6091 : #endif
6092 : }
6093 :
6094 : /*
6095 : * Both these CPU hotplug callbacks race against unregister_fair_sched_group()
6096 : *
6097 : * The race is harmless, since modifying bandwidth settings of unhooked group
6098 : * bits doesn't do much.
6099 : */
6100 :
6101 : /* cpu online callback */
6102 : static void __maybe_unused update_runtime_enabled(struct rq *rq)
6103 : {
6104 : struct task_group *tg;
6105 :
6106 : lockdep_assert_rq_held(rq);
6107 :
6108 : rcu_read_lock();
6109 : list_for_each_entry_rcu(tg, &task_groups, list) {
6110 : struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
6111 : struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
6112 :
6113 : raw_spin_lock(&cfs_b->lock);
6114 : cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
6115 : raw_spin_unlock(&cfs_b->lock);
6116 : }
6117 : rcu_read_unlock();
6118 : }
6119 :
6120 : /* cpu offline callback */
6121 : static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
6122 : {
6123 : struct task_group *tg;
6124 :
6125 : lockdep_assert_rq_held(rq);
6126 :
6127 : /*
6128 : * The rq clock has already been updated in the
6129 : * set_rq_offline(), so we should skip updating
6130 : * the rq clock again in unthrottle_cfs_rq().
6131 : */
6132 : rq_clock_start_loop_update(rq);
6133 :
6134 : rcu_read_lock();
6135 : list_for_each_entry_rcu(tg, &task_groups, list) {
6136 : struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
6137 :
6138 : if (!cfs_rq->runtime_enabled)
6139 : continue;
6140 :
6141 : /*
6142 : * clock_task is not advancing so we just need to make sure
6143 : * there's some valid quota amount
6144 : */
6145 : cfs_rq->runtime_remaining = 1;
6146 : /*
6147 : * Offline rq is schedulable till CPU is completely disabled
6148 : * in take_cpu_down(), so we prevent new cfs throttling here.
6149 : */
6150 : cfs_rq->runtime_enabled = 0;
6151 :
6152 : if (cfs_rq_throttled(cfs_rq))
6153 : unthrottle_cfs_rq(cfs_rq);
6154 : }
6155 : rcu_read_unlock();
6156 :
6157 : rq_clock_stop_loop_update(rq);
6158 : }
6159 :
6160 : #else /* CONFIG_CFS_BANDWIDTH */
6161 :
6162 : static inline bool cfs_bandwidth_used(void)
6163 : {
6164 : return false;
6165 : }
6166 :
6167 : static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {}
6168 : static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; }
6169 : static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
6170 : static inline void sync_throttle(struct task_group *tg, int cpu) {}
6171 : static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
6172 :
6173 : static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
6174 : {
6175 : return 0;
6176 : }
6177 :
6178 : static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
6179 : {
6180 : return 0;
6181 : }
6182 :
6183 : static inline int throttled_lb_pair(struct task_group *tg,
6184 : int src_cpu, int dest_cpu)
6185 : {
6186 : return 0;
6187 : }
6188 :
6189 0 : void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
6190 :
6191 : #ifdef CONFIG_FAIR_GROUP_SCHED
6192 : static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
6193 : #endif
6194 :
6195 : static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
6196 : {
6197 : return NULL;
6198 : }
6199 : static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
6200 : static inline void update_runtime_enabled(struct rq *rq) {}
6201 : static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
6202 :
6203 : #endif /* CONFIG_CFS_BANDWIDTH */
6204 :
6205 : /**************************************************
6206 : * CFS operations on tasks:
6207 : */
6208 :
6209 : #ifdef CONFIG_SCHED_HRTICK
6210 : static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
6211 : {
6212 : struct sched_entity *se = &p->se;
6213 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
6214 :
6215 : SCHED_WARN_ON(task_rq(p) != rq);
6216 :
6217 : if (rq->cfs.h_nr_running > 1) {
6218 : u64 slice = sched_slice(cfs_rq, se);
6219 : u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
6220 : s64 delta = slice - ran;
6221 :
6222 : if (delta < 0) {
6223 : if (task_current(rq, p))
6224 : resched_curr(rq);
6225 : return;
6226 : }
6227 : hrtick_start(rq, delta);
6228 : }
6229 : }
6230 :
6231 : /*
6232 : * called from enqueue/dequeue and updates the hrtick when the
6233 : * current task is from our class and nr_running is low enough
6234 : * to matter.
6235 : */
6236 : static void hrtick_update(struct rq *rq)
6237 : {
6238 : struct task_struct *curr = rq->curr;
6239 :
6240 : if (!hrtick_enabled_fair(rq) || curr->sched_class != &fair_sched_class)
6241 : return;
6242 :
6243 : if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
6244 : hrtick_start_fair(rq, curr);
6245 : }
6246 : #else /* !CONFIG_SCHED_HRTICK */
6247 : static inline void
6248 : hrtick_start_fair(struct rq *rq, struct task_struct *p)
6249 : {
6250 : }
6251 :
6252 : static inline void hrtick_update(struct rq *rq)
6253 : {
6254 : }
6255 : #endif
6256 :
6257 : #ifdef CONFIG_SMP
6258 : static inline bool cpu_overutilized(int cpu)
6259 : {
6260 : unsigned long rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN);
6261 : unsigned long rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX);
6262 :
6263 : /* Return true only if the utilization doesn't fit CPU's capacity */
6264 : return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu);
6265 : }
6266 :
6267 : static inline void update_overutilized_status(struct rq *rq)
6268 : {
6269 : if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) {
6270 : WRITE_ONCE(rq->rd->overutilized, SG_OVERUTILIZED);
6271 : trace_sched_overutilized_tp(rq->rd, SG_OVERUTILIZED);
6272 : }
6273 : }
6274 : #else
6275 : static inline void update_overutilized_status(struct rq *rq) { }
6276 : #endif
6277 :
6278 : /* Runqueue only has SCHED_IDLE tasks enqueued */
6279 : static int sched_idle_rq(struct rq *rq)
6280 : {
6281 2066 : return unlikely(rq->nr_running == rq->cfs.idle_h_nr_running &&
6282 : rq->nr_running);
6283 : }
6284 :
6285 : /*
6286 : * Returns true if cfs_rq only has SCHED_IDLE entities enqueued. Note the use
6287 : * of idle_nr_running, which does not consider idle descendants of normal
6288 : * entities.
6289 : */
6290 : static bool sched_idle_cfs_rq(struct cfs_rq *cfs_rq)
6291 : {
6292 : return cfs_rq->nr_running &&
6293 : cfs_rq->nr_running == cfs_rq->idle_nr_running;
6294 : }
6295 :
6296 : #ifdef CONFIG_SMP
6297 : static int sched_idle_cpu(int cpu)
6298 : {
6299 : return sched_idle_rq(cpu_rq(cpu));
6300 : }
6301 : #endif
6302 :
6303 : /*
6304 : * The enqueue_task method is called before nr_running is
6305 : * increased. Here we update the fair scheduling stats and
6306 : * then put the task into the rbtree:
6307 : */
6308 : static void
6309 1035 : enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
6310 : {
6311 : struct cfs_rq *cfs_rq;
6312 1035 : struct sched_entity *se = &p->se;
6313 2070 : int idle_h_nr_running = task_has_idle_policy(p);
6314 1035 : int task_new = !(flags & ENQUEUE_WAKEUP);
6315 :
6316 : /*
6317 : * The code below (indirectly) updates schedutil which looks at
6318 : * the cfs_rq utilization to select a frequency.
6319 : * Let's add the task's estimated utilization to the cfs_rq's
6320 : * estimated utilization, before we update schedutil.
6321 : */
6322 1035 : util_est_enqueue(&rq->cfs, p);
6323 :
6324 : /*
6325 : * If in_iowait is set, the code below may not trigger any cpufreq
6326 : * utilization updates, so do it here explicitly with the IOWAIT flag
6327 : * passed.
6328 : */
6329 : if (p->in_iowait)
6330 : cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
6331 :
6332 2070 : for_each_sched_entity(se) {
6333 1035 : if (se->on_rq)
6334 : break;
6335 2070 : cfs_rq = cfs_rq_of(se);
6336 1035 : enqueue_entity(cfs_rq, se, flags);
6337 :
6338 1035 : cfs_rq->h_nr_running++;
6339 1035 : cfs_rq->idle_h_nr_running += idle_h_nr_running;
6340 :
6341 : if (cfs_rq_is_idle(cfs_rq))
6342 : idle_h_nr_running = 1;
6343 :
6344 : /* end evaluation on encountering a throttled cfs_rq */
6345 : if (cfs_rq_throttled(cfs_rq))
6346 : goto enqueue_throttle;
6347 :
6348 : flags = ENQUEUE_WAKEUP;
6349 : }
6350 :
6351 1035 : for_each_sched_entity(se) {
6352 0 : cfs_rq = cfs_rq_of(se);
6353 :
6354 0 : update_load_avg(cfs_rq, se, UPDATE_TG);
6355 0 : se_update_runnable(se);
6356 0 : update_cfs_group(se);
6357 :
6358 0 : cfs_rq->h_nr_running++;
6359 0 : cfs_rq->idle_h_nr_running += idle_h_nr_running;
6360 :
6361 : if (cfs_rq_is_idle(cfs_rq))
6362 : idle_h_nr_running = 1;
6363 :
6364 : /* end evaluation on encountering a throttled cfs_rq */
6365 : if (cfs_rq_throttled(cfs_rq))
6366 : goto enqueue_throttle;
6367 : }
6368 :
6369 : /* At this point se is NULL and we are at root level*/
6370 2070 : add_nr_running(rq, 1);
6371 :
6372 : /*
6373 : * Since new tasks are assigned an initial util_avg equal to
6374 : * half of the spare capacity of their CPU, tiny tasks have the
6375 : * ability to cross the overutilized threshold, which will
6376 : * result in the load balancer ruining all the task placement
6377 : * done by EAS. As a way to mitigate that effect, do not account
6378 : * for the first enqueue operation of new tasks during the
6379 : * overutilized flag detection.
6380 : *
6381 : * A better way of solving this problem would be to wait for
6382 : * the PELT signals of tasks to converge before taking them
6383 : * into account, but that is not straightforward to implement,
6384 : * and the following generally works well enough in practice.
6385 : */
6386 : if (!task_new)
6387 : update_overutilized_status(rq);
6388 :
6389 : enqueue_throttle:
6390 1035 : assert_list_leaf_cfs_rq(rq);
6391 :
6392 1035 : hrtick_update(rq);
6393 1035 : }
6394 :
6395 : static void set_next_buddy(struct sched_entity *se);
6396 :
6397 : /*
6398 : * The dequeue_task method is called before nr_running is
6399 : * decreased. We remove the task from the rbtree and
6400 : * update the fair scheduling stats:
6401 : */
6402 1033 : static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
6403 : {
6404 : struct cfs_rq *cfs_rq;
6405 1033 : struct sched_entity *se = &p->se;
6406 1033 : int task_sleep = flags & DEQUEUE_SLEEP;
6407 2066 : int idle_h_nr_running = task_has_idle_policy(p);
6408 2066 : bool was_sched_idle = sched_idle_rq(rq);
6409 :
6410 1033 : util_est_dequeue(&rq->cfs, p);
6411 :
6412 1 : for_each_sched_entity(se) {
6413 2066 : cfs_rq = cfs_rq_of(se);
6414 1033 : dequeue_entity(cfs_rq, se, flags);
6415 :
6416 1033 : cfs_rq->h_nr_running--;
6417 1033 : cfs_rq->idle_h_nr_running -= idle_h_nr_running;
6418 :
6419 : if (cfs_rq_is_idle(cfs_rq))
6420 : idle_h_nr_running = 1;
6421 :
6422 : /* end evaluation on encountering a throttled cfs_rq */
6423 : if (cfs_rq_throttled(cfs_rq))
6424 : goto dequeue_throttle;
6425 :
6426 : /* Don't dequeue parent if it has other entities besides us */
6427 1033 : if (cfs_rq->load.weight) {
6428 : /* Avoid re-evaluating load for this entity: */
6429 : se = parent_entity(se);
6430 : /*
6431 : * Bias pick_next to pick a task from this cfs_rq, as
6432 : * p is sleeping when it is within its sched_slice.
6433 : */
6434 : if (task_sleep && se && !throttled_hierarchy(cfs_rq))
6435 : set_next_buddy(se);
6436 : break;
6437 : }
6438 1 : flags |= DEQUEUE_SLEEP;
6439 : }
6440 :
6441 1033 : for_each_sched_entity(se) {
6442 0 : cfs_rq = cfs_rq_of(se);
6443 :
6444 0 : update_load_avg(cfs_rq, se, UPDATE_TG);
6445 0 : se_update_runnable(se);
6446 0 : update_cfs_group(se);
6447 :
6448 0 : cfs_rq->h_nr_running--;
6449 0 : cfs_rq->idle_h_nr_running -= idle_h_nr_running;
6450 :
6451 : if (cfs_rq_is_idle(cfs_rq))
6452 : idle_h_nr_running = 1;
6453 :
6454 : /* end evaluation on encountering a throttled cfs_rq */
6455 : if (cfs_rq_throttled(cfs_rq))
6456 : goto dequeue_throttle;
6457 :
6458 : }
6459 :
6460 : /* At this point se is NULL and we are at root level*/
6461 2066 : sub_nr_running(rq, 1);
6462 :
6463 : /* balance early to pull high priority tasks */
6464 2066 : if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
6465 0 : rq->next_balance = jiffies;
6466 :
6467 : dequeue_throttle:
6468 1033 : util_est_update(&rq->cfs, p, task_sleep);
6469 1033 : hrtick_update(rq);
6470 1033 : }
6471 :
6472 : #ifdef CONFIG_SMP
6473 :
6474 : /* Working cpumask for: load_balance, load_balance_newidle. */
6475 : static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
6476 : static DEFINE_PER_CPU(cpumask_var_t, select_rq_mask);
6477 :
6478 : #ifdef CONFIG_NO_HZ_COMMON
6479 :
6480 : static struct {
6481 : cpumask_var_t idle_cpus_mask;
6482 : atomic_t nr_cpus;
6483 : int has_blocked; /* Idle CPUS has blocked load */
6484 : int needs_update; /* Newly idle CPUs need their next_balance collated */
6485 : unsigned long next_balance; /* in jiffy units */
6486 : unsigned long next_blocked; /* Next update of blocked load in jiffies */
6487 : } nohz ____cacheline_aligned;
6488 :
6489 : #endif /* CONFIG_NO_HZ_COMMON */
6490 :
6491 : static unsigned long cpu_load(struct rq *rq)
6492 : {
6493 : return cfs_rq_load_avg(&rq->cfs);
6494 : }
6495 :
6496 : /*
6497 : * cpu_load_without - compute CPU load without any contributions from *p
6498 : * @cpu: the CPU which load is requested
6499 : * @p: the task which load should be discounted
6500 : *
6501 : * The load of a CPU is defined by the load of tasks currently enqueued on that
6502 : * CPU as well as tasks which are currently sleeping after an execution on that
6503 : * CPU.
6504 : *
6505 : * This method returns the load of the specified CPU by discounting the load of
6506 : * the specified task, whenever the task is currently contributing to the CPU
6507 : * load.
6508 : */
6509 : static unsigned long cpu_load_without(struct rq *rq, struct task_struct *p)
6510 : {
6511 : struct cfs_rq *cfs_rq;
6512 : unsigned int load;
6513 :
6514 : /* Task has no contribution or is new */
6515 : if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
6516 : return cpu_load(rq);
6517 :
6518 : cfs_rq = &rq->cfs;
6519 : load = READ_ONCE(cfs_rq->avg.load_avg);
6520 :
6521 : /* Discount task's util from CPU's util */
6522 : lsub_positive(&load, task_h_load(p));
6523 :
6524 : return load;
6525 : }
6526 :
6527 : static unsigned long cpu_runnable(struct rq *rq)
6528 : {
6529 : return cfs_rq_runnable_avg(&rq->cfs);
6530 : }
6531 :
6532 : static unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p)
6533 : {
6534 : struct cfs_rq *cfs_rq;
6535 : unsigned int runnable;
6536 :
6537 : /* Task has no contribution or is new */
6538 : if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
6539 : return cpu_runnable(rq);
6540 :
6541 : cfs_rq = &rq->cfs;
6542 : runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
6543 :
6544 : /* Discount task's runnable from CPU's runnable */
6545 : lsub_positive(&runnable, p->se.avg.runnable_avg);
6546 :
6547 : return runnable;
6548 : }
6549 :
6550 : static unsigned long capacity_of(int cpu)
6551 : {
6552 : return cpu_rq(cpu)->cpu_capacity;
6553 : }
6554 :
6555 : static void record_wakee(struct task_struct *p)
6556 : {
6557 : /*
6558 : * Only decay a single time; tasks that have less then 1 wakeup per
6559 : * jiffy will not have built up many flips.
6560 : */
6561 : if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) {
6562 : current->wakee_flips >>= 1;
6563 : current->wakee_flip_decay_ts = jiffies;
6564 : }
6565 :
6566 : if (current->last_wakee != p) {
6567 : current->last_wakee = p;
6568 : current->wakee_flips++;
6569 : }
6570 : }
6571 :
6572 : /*
6573 : * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
6574 : *
6575 : * A waker of many should wake a different task than the one last awakened
6576 : * at a frequency roughly N times higher than one of its wakees.
6577 : *
6578 : * In order to determine whether we should let the load spread vs consolidating
6579 : * to shared cache, we look for a minimum 'flip' frequency of llc_size in one
6580 : * partner, and a factor of lls_size higher frequency in the other.
6581 : *
6582 : * With both conditions met, we can be relatively sure that the relationship is
6583 : * non-monogamous, with partner count exceeding socket size.
6584 : *
6585 : * Waker/wakee being client/server, worker/dispatcher, interrupt source or
6586 : * whatever is irrelevant, spread criteria is apparent partner count exceeds
6587 : * socket size.
6588 : */
6589 : static int wake_wide(struct task_struct *p)
6590 : {
6591 : unsigned int master = current->wakee_flips;
6592 : unsigned int slave = p->wakee_flips;
6593 : int factor = __this_cpu_read(sd_llc_size);
6594 :
6595 : if (master < slave)
6596 : swap(master, slave);
6597 : if (slave < factor || master < slave * factor)
6598 : return 0;
6599 : return 1;
6600 : }
6601 :
6602 : /*
6603 : * The purpose of wake_affine() is to quickly determine on which CPU we can run
6604 : * soonest. For the purpose of speed we only consider the waking and previous
6605 : * CPU.
6606 : *
6607 : * wake_affine_idle() - only considers 'now', it check if the waking CPU is
6608 : * cache-affine and is (or will be) idle.
6609 : *
6610 : * wake_affine_weight() - considers the weight to reflect the average
6611 : * scheduling latency of the CPUs. This seems to work
6612 : * for the overloaded case.
6613 : */
6614 : static int
6615 : wake_affine_idle(int this_cpu, int prev_cpu, int sync)
6616 : {
6617 : /*
6618 : * If this_cpu is idle, it implies the wakeup is from interrupt
6619 : * context. Only allow the move if cache is shared. Otherwise an
6620 : * interrupt intensive workload could force all tasks onto one
6621 : * node depending on the IO topology or IRQ affinity settings.
6622 : *
6623 : * If the prev_cpu is idle and cache affine then avoid a migration.
6624 : * There is no guarantee that the cache hot data from an interrupt
6625 : * is more important than cache hot data on the prev_cpu and from
6626 : * a cpufreq perspective, it's better to have higher utilisation
6627 : * on one CPU.
6628 : */
6629 : if (available_idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
6630 : return available_idle_cpu(prev_cpu) ? prev_cpu : this_cpu;
6631 :
6632 : if (sync && cpu_rq(this_cpu)->nr_running == 1)
6633 : return this_cpu;
6634 :
6635 : if (available_idle_cpu(prev_cpu))
6636 : return prev_cpu;
6637 :
6638 : return nr_cpumask_bits;
6639 : }
6640 :
6641 : static int
6642 : wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
6643 : int this_cpu, int prev_cpu, int sync)
6644 : {
6645 : s64 this_eff_load, prev_eff_load;
6646 : unsigned long task_load;
6647 :
6648 : this_eff_load = cpu_load(cpu_rq(this_cpu));
6649 :
6650 : if (sync) {
6651 : unsigned long current_load = task_h_load(current);
6652 :
6653 : if (current_load > this_eff_load)
6654 : return this_cpu;
6655 :
6656 : this_eff_load -= current_load;
6657 : }
6658 :
6659 : task_load = task_h_load(p);
6660 :
6661 : this_eff_load += task_load;
6662 : if (sched_feat(WA_BIAS))
6663 : this_eff_load *= 100;
6664 : this_eff_load *= capacity_of(prev_cpu);
6665 :
6666 : prev_eff_load = cpu_load(cpu_rq(prev_cpu));
6667 : prev_eff_load -= task_load;
6668 : if (sched_feat(WA_BIAS))
6669 : prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
6670 : prev_eff_load *= capacity_of(this_cpu);
6671 :
6672 : /*
6673 : * If sync, adjust the weight of prev_eff_load such that if
6674 : * prev_eff == this_eff that select_idle_sibling() will consider
6675 : * stacking the wakee on top of the waker if no other CPU is
6676 : * idle.
6677 : */
6678 : if (sync)
6679 : prev_eff_load += 1;
6680 :
6681 : return this_eff_load < prev_eff_load ? this_cpu : nr_cpumask_bits;
6682 : }
6683 :
6684 : static int wake_affine(struct sched_domain *sd, struct task_struct *p,
6685 : int this_cpu, int prev_cpu, int sync)
6686 : {
6687 : int target = nr_cpumask_bits;
6688 :
6689 : if (sched_feat(WA_IDLE))
6690 : target = wake_affine_idle(this_cpu, prev_cpu, sync);
6691 :
6692 : if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
6693 : target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
6694 :
6695 : schedstat_inc(p->stats.nr_wakeups_affine_attempts);
6696 : if (target != this_cpu)
6697 : return prev_cpu;
6698 :
6699 : schedstat_inc(sd->ttwu_move_affine);
6700 : schedstat_inc(p->stats.nr_wakeups_affine);
6701 : return target;
6702 : }
6703 :
6704 : static struct sched_group *
6705 : find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
6706 :
6707 : /*
6708 : * find_idlest_group_cpu - find the idlest CPU among the CPUs in the group.
6709 : */
6710 : static int
6711 : find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
6712 : {
6713 : unsigned long load, min_load = ULONG_MAX;
6714 : unsigned int min_exit_latency = UINT_MAX;
6715 : u64 latest_idle_timestamp = 0;
6716 : int least_loaded_cpu = this_cpu;
6717 : int shallowest_idle_cpu = -1;
6718 : int i;
6719 :
6720 : /* Check if we have any choice: */
6721 : if (group->group_weight == 1)
6722 : return cpumask_first(sched_group_span(group));
6723 :
6724 : /* Traverse only the allowed CPUs */
6725 : for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
6726 : struct rq *rq = cpu_rq(i);
6727 :
6728 : if (!sched_core_cookie_match(rq, p))
6729 : continue;
6730 :
6731 : if (sched_idle_cpu(i))
6732 : return i;
6733 :
6734 : if (available_idle_cpu(i)) {
6735 : struct cpuidle_state *idle = idle_get_state(rq);
6736 : if (idle && idle->exit_latency < min_exit_latency) {
6737 : /*
6738 : * We give priority to a CPU whose idle state
6739 : * has the smallest exit latency irrespective
6740 : * of any idle timestamp.
6741 : */
6742 : min_exit_latency = idle->exit_latency;
6743 : latest_idle_timestamp = rq->idle_stamp;
6744 : shallowest_idle_cpu = i;
6745 : } else if ((!idle || idle->exit_latency == min_exit_latency) &&
6746 : rq->idle_stamp > latest_idle_timestamp) {
6747 : /*
6748 : * If equal or no active idle state, then
6749 : * the most recently idled CPU might have
6750 : * a warmer cache.
6751 : */
6752 : latest_idle_timestamp = rq->idle_stamp;
6753 : shallowest_idle_cpu = i;
6754 : }
6755 : } else if (shallowest_idle_cpu == -1) {
6756 : load = cpu_load(cpu_rq(i));
6757 : if (load < min_load) {
6758 : min_load = load;
6759 : least_loaded_cpu = i;
6760 : }
6761 : }
6762 : }
6763 :
6764 : return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
6765 : }
6766 :
6767 : static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
6768 : int cpu, int prev_cpu, int sd_flag)
6769 : {
6770 : int new_cpu = cpu;
6771 :
6772 : if (!cpumask_intersects(sched_domain_span(sd), p->cpus_ptr))
6773 : return prev_cpu;
6774 :
6775 : /*
6776 : * We need task's util for cpu_util_without, sync it up to
6777 : * prev_cpu's last_update_time.
6778 : */
6779 : if (!(sd_flag & SD_BALANCE_FORK))
6780 : sync_entity_load_avg(&p->se);
6781 :
6782 : while (sd) {
6783 : struct sched_group *group;
6784 : struct sched_domain *tmp;
6785 : int weight;
6786 :
6787 : if (!(sd->flags & sd_flag)) {
6788 : sd = sd->child;
6789 : continue;
6790 : }
6791 :
6792 : group = find_idlest_group(sd, p, cpu);
6793 : if (!group) {
6794 : sd = sd->child;
6795 : continue;
6796 : }
6797 :
6798 : new_cpu = find_idlest_group_cpu(group, p, cpu);
6799 : if (new_cpu == cpu) {
6800 : /* Now try balancing at a lower domain level of 'cpu': */
6801 : sd = sd->child;
6802 : continue;
6803 : }
6804 :
6805 : /* Now try balancing at a lower domain level of 'new_cpu': */
6806 : cpu = new_cpu;
6807 : weight = sd->span_weight;
6808 : sd = NULL;
6809 : for_each_domain(cpu, tmp) {
6810 : if (weight <= tmp->span_weight)
6811 : break;
6812 : if (tmp->flags & sd_flag)
6813 : sd = tmp;
6814 : }
6815 : }
6816 :
6817 : return new_cpu;
6818 : }
6819 :
6820 : static inline int __select_idle_cpu(int cpu, struct task_struct *p)
6821 : {
6822 : if ((available_idle_cpu(cpu) || sched_idle_cpu(cpu)) &&
6823 : sched_cpu_cookie_match(cpu_rq(cpu), p))
6824 : return cpu;
6825 :
6826 : return -1;
6827 : }
6828 :
6829 : #ifdef CONFIG_SCHED_SMT
6830 : DEFINE_STATIC_KEY_FALSE(sched_smt_present);
6831 : EXPORT_SYMBOL_GPL(sched_smt_present);
6832 :
6833 : static inline void set_idle_cores(int cpu, int val)
6834 : {
6835 : struct sched_domain_shared *sds;
6836 :
6837 : sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
6838 : if (sds)
6839 : WRITE_ONCE(sds->has_idle_cores, val);
6840 : }
6841 :
6842 : static inline bool test_idle_cores(int cpu)
6843 : {
6844 : struct sched_domain_shared *sds;
6845 :
6846 : sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
6847 : if (sds)
6848 : return READ_ONCE(sds->has_idle_cores);
6849 :
6850 : return false;
6851 : }
6852 :
6853 : /*
6854 : * Scans the local SMT mask to see if the entire core is idle, and records this
6855 : * information in sd_llc_shared->has_idle_cores.
6856 : *
6857 : * Since SMT siblings share all cache levels, inspecting this limited remote
6858 : * state should be fairly cheap.
6859 : */
6860 : void __update_idle_core(struct rq *rq)
6861 : {
6862 : int core = cpu_of(rq);
6863 : int cpu;
6864 :
6865 : rcu_read_lock();
6866 : if (test_idle_cores(core))
6867 : goto unlock;
6868 :
6869 : for_each_cpu(cpu, cpu_smt_mask(core)) {
6870 : if (cpu == core)
6871 : continue;
6872 :
6873 : if (!available_idle_cpu(cpu))
6874 : goto unlock;
6875 : }
6876 :
6877 : set_idle_cores(core, 1);
6878 : unlock:
6879 : rcu_read_unlock();
6880 : }
6881 :
6882 : /*
6883 : * Scan the entire LLC domain for idle cores; this dynamically switches off if
6884 : * there are no idle cores left in the system; tracked through
6885 : * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
6886 : */
6887 : static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
6888 : {
6889 : bool idle = true;
6890 : int cpu;
6891 :
6892 : for_each_cpu(cpu, cpu_smt_mask(core)) {
6893 : if (!available_idle_cpu(cpu)) {
6894 : idle = false;
6895 : if (*idle_cpu == -1) {
6896 : if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, p->cpus_ptr)) {
6897 : *idle_cpu = cpu;
6898 : break;
6899 : }
6900 : continue;
6901 : }
6902 : break;
6903 : }
6904 : if (*idle_cpu == -1 && cpumask_test_cpu(cpu, p->cpus_ptr))
6905 : *idle_cpu = cpu;
6906 : }
6907 :
6908 : if (idle)
6909 : return core;
6910 :
6911 : cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
6912 : return -1;
6913 : }
6914 :
6915 : /*
6916 : * Scan the local SMT mask for idle CPUs.
6917 : */
6918 : static int select_idle_smt(struct task_struct *p, int target)
6919 : {
6920 : int cpu;
6921 :
6922 : for_each_cpu_and(cpu, cpu_smt_mask(target), p->cpus_ptr) {
6923 : if (cpu == target)
6924 : continue;
6925 : if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
6926 : return cpu;
6927 : }
6928 :
6929 : return -1;
6930 : }
6931 :
6932 : #else /* CONFIG_SCHED_SMT */
6933 :
6934 : static inline void set_idle_cores(int cpu, int val)
6935 : {
6936 : }
6937 :
6938 : static inline bool test_idle_cores(int cpu)
6939 : {
6940 : return false;
6941 : }
6942 :
6943 : static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
6944 : {
6945 : return __select_idle_cpu(core, p);
6946 : }
6947 :
6948 : static inline int select_idle_smt(struct task_struct *p, int target)
6949 : {
6950 : return -1;
6951 : }
6952 :
6953 : #endif /* CONFIG_SCHED_SMT */
6954 :
6955 : /*
6956 : * Scan the LLC domain for idle CPUs; this is dynamically regulated by
6957 : * comparing the average scan cost (tracked in sd->avg_scan_cost) against the
6958 : * average idle time for this rq (as found in rq->avg_idle).
6959 : */
6960 : static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool has_idle_core, int target)
6961 : {
6962 : struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
6963 : int i, cpu, idle_cpu = -1, nr = INT_MAX;
6964 : struct sched_domain_shared *sd_share;
6965 : struct rq *this_rq = this_rq();
6966 : int this = smp_processor_id();
6967 : struct sched_domain *this_sd = NULL;
6968 : u64 time = 0;
6969 :
6970 : cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
6971 :
6972 : if (sched_feat(SIS_PROP) && !has_idle_core) {
6973 : u64 avg_cost, avg_idle, span_avg;
6974 : unsigned long now = jiffies;
6975 :
6976 : this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
6977 : if (!this_sd)
6978 : return -1;
6979 :
6980 : /*
6981 : * If we're busy, the assumption that the last idle period
6982 : * predicts the future is flawed; age away the remaining
6983 : * predicted idle time.
6984 : */
6985 : if (unlikely(this_rq->wake_stamp < now)) {
6986 : while (this_rq->wake_stamp < now && this_rq->wake_avg_idle) {
6987 : this_rq->wake_stamp++;
6988 : this_rq->wake_avg_idle >>= 1;
6989 : }
6990 : }
6991 :
6992 : avg_idle = this_rq->wake_avg_idle;
6993 : avg_cost = this_sd->avg_scan_cost + 1;
6994 :
6995 : span_avg = sd->span_weight * avg_idle;
6996 : if (span_avg > 4*avg_cost)
6997 : nr = div_u64(span_avg, avg_cost);
6998 : else
6999 : nr = 4;
7000 :
7001 : time = cpu_clock(this);
7002 : }
7003 :
7004 : if (sched_feat(SIS_UTIL)) {
7005 : sd_share = rcu_dereference(per_cpu(sd_llc_shared, target));
7006 : if (sd_share) {
7007 : /* because !--nr is the condition to stop scan */
7008 : nr = READ_ONCE(sd_share->nr_idle_scan) + 1;
7009 : /* overloaded LLC is unlikely to have idle cpu/core */
7010 : if (nr == 1)
7011 : return -1;
7012 : }
7013 : }
7014 :
7015 : for_each_cpu_wrap(cpu, cpus, target + 1) {
7016 : if (has_idle_core) {
7017 : i = select_idle_core(p, cpu, cpus, &idle_cpu);
7018 : if ((unsigned int)i < nr_cpumask_bits)
7019 : return i;
7020 :
7021 : } else {
7022 : if (!--nr)
7023 : return -1;
7024 : idle_cpu = __select_idle_cpu(cpu, p);
7025 : if ((unsigned int)idle_cpu < nr_cpumask_bits)
7026 : break;
7027 : }
7028 : }
7029 :
7030 : if (has_idle_core)
7031 : set_idle_cores(target, false);
7032 :
7033 : if (sched_feat(SIS_PROP) && this_sd && !has_idle_core) {
7034 : time = cpu_clock(this) - time;
7035 :
7036 : /*
7037 : * Account for the scan cost of wakeups against the average
7038 : * idle time.
7039 : */
7040 : this_rq->wake_avg_idle -= min(this_rq->wake_avg_idle, time);
7041 :
7042 : update_avg(&this_sd->avg_scan_cost, time);
7043 : }
7044 :
7045 : return idle_cpu;
7046 : }
7047 :
7048 : /*
7049 : * Scan the asym_capacity domain for idle CPUs; pick the first idle one on which
7050 : * the task fits. If no CPU is big enough, but there are idle ones, try to
7051 : * maximize capacity.
7052 : */
7053 : static int
7054 : select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
7055 : {
7056 : unsigned long task_util, util_min, util_max, best_cap = 0;
7057 : int fits, best_fits = 0;
7058 : int cpu, best_cpu = -1;
7059 : struct cpumask *cpus;
7060 :
7061 : cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
7062 : cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
7063 :
7064 : task_util = task_util_est(p);
7065 : util_min = uclamp_eff_value(p, UCLAMP_MIN);
7066 : util_max = uclamp_eff_value(p, UCLAMP_MAX);
7067 :
7068 : for_each_cpu_wrap(cpu, cpus, target + 1) {
7069 : unsigned long cpu_cap = capacity_of(cpu);
7070 :
7071 : if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu))
7072 : continue;
7073 :
7074 : fits = util_fits_cpu(task_util, util_min, util_max, cpu);
7075 :
7076 : /* This CPU fits with all requirements */
7077 : if (fits > 0)
7078 : return cpu;
7079 : /*
7080 : * Only the min performance hint (i.e. uclamp_min) doesn't fit.
7081 : * Look for the CPU with best capacity.
7082 : */
7083 : else if (fits < 0)
7084 : cpu_cap = capacity_orig_of(cpu) - thermal_load_avg(cpu_rq(cpu));
7085 :
7086 : /*
7087 : * First, select CPU which fits better (-1 being better than 0).
7088 : * Then, select the one with best capacity at same level.
7089 : */
7090 : if ((fits < best_fits) ||
7091 : ((fits == best_fits) && (cpu_cap > best_cap))) {
7092 : best_cap = cpu_cap;
7093 : best_cpu = cpu;
7094 : best_fits = fits;
7095 : }
7096 : }
7097 :
7098 : return best_cpu;
7099 : }
7100 :
7101 : static inline bool asym_fits_cpu(unsigned long util,
7102 : unsigned long util_min,
7103 : unsigned long util_max,
7104 : int cpu)
7105 : {
7106 : if (sched_asym_cpucap_active())
7107 : /*
7108 : * Return true only if the cpu fully fits the task requirements
7109 : * which include the utilization and the performance hints.
7110 : */
7111 : return (util_fits_cpu(util, util_min, util_max, cpu) > 0);
7112 :
7113 : return true;
7114 : }
7115 :
7116 : /*
7117 : * Try and locate an idle core/thread in the LLC cache domain.
7118 : */
7119 : static int select_idle_sibling(struct task_struct *p, int prev, int target)
7120 : {
7121 : bool has_idle_core = false;
7122 : struct sched_domain *sd;
7123 : unsigned long task_util, util_min, util_max;
7124 : int i, recent_used_cpu;
7125 :
7126 : /*
7127 : * On asymmetric system, update task utilization because we will check
7128 : * that the task fits with cpu's capacity.
7129 : */
7130 : if (sched_asym_cpucap_active()) {
7131 : sync_entity_load_avg(&p->se);
7132 : task_util = task_util_est(p);
7133 : util_min = uclamp_eff_value(p, UCLAMP_MIN);
7134 : util_max = uclamp_eff_value(p, UCLAMP_MAX);
7135 : }
7136 :
7137 : /*
7138 : * per-cpu select_rq_mask usage
7139 : */
7140 : lockdep_assert_irqs_disabled();
7141 :
7142 : if ((available_idle_cpu(target) || sched_idle_cpu(target)) &&
7143 : asym_fits_cpu(task_util, util_min, util_max, target))
7144 : return target;
7145 :
7146 : /*
7147 : * If the previous CPU is cache affine and idle, don't be stupid:
7148 : */
7149 : if (prev != target && cpus_share_cache(prev, target) &&
7150 : (available_idle_cpu(prev) || sched_idle_cpu(prev)) &&
7151 : asym_fits_cpu(task_util, util_min, util_max, prev))
7152 : return prev;
7153 :
7154 : /*
7155 : * Allow a per-cpu kthread to stack with the wakee if the
7156 : * kworker thread and the tasks previous CPUs are the same.
7157 : * The assumption is that the wakee queued work for the
7158 : * per-cpu kthread that is now complete and the wakeup is
7159 : * essentially a sync wakeup. An obvious example of this
7160 : * pattern is IO completions.
7161 : */
7162 : if (is_per_cpu_kthread(current) &&
7163 : in_task() &&
7164 : prev == smp_processor_id() &&
7165 : this_rq()->nr_running <= 1 &&
7166 : asym_fits_cpu(task_util, util_min, util_max, prev)) {
7167 : return prev;
7168 : }
7169 :
7170 : /* Check a recently used CPU as a potential idle candidate: */
7171 : recent_used_cpu = p->recent_used_cpu;
7172 : p->recent_used_cpu = prev;
7173 : if (recent_used_cpu != prev &&
7174 : recent_used_cpu != target &&
7175 : cpus_share_cache(recent_used_cpu, target) &&
7176 : (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
7177 : cpumask_test_cpu(recent_used_cpu, p->cpus_ptr) &&
7178 : asym_fits_cpu(task_util, util_min, util_max, recent_used_cpu)) {
7179 : return recent_used_cpu;
7180 : }
7181 :
7182 : /*
7183 : * For asymmetric CPU capacity systems, our domain of interest is
7184 : * sd_asym_cpucapacity rather than sd_llc.
7185 : */
7186 : if (sched_asym_cpucap_active()) {
7187 : sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target));
7188 : /*
7189 : * On an asymmetric CPU capacity system where an exclusive
7190 : * cpuset defines a symmetric island (i.e. one unique
7191 : * capacity_orig value through the cpuset), the key will be set
7192 : * but the CPUs within that cpuset will not have a domain with
7193 : * SD_ASYM_CPUCAPACITY. These should follow the usual symmetric
7194 : * capacity path.
7195 : */
7196 : if (sd) {
7197 : i = select_idle_capacity(p, sd, target);
7198 : return ((unsigned)i < nr_cpumask_bits) ? i : target;
7199 : }
7200 : }
7201 :
7202 : sd = rcu_dereference(per_cpu(sd_llc, target));
7203 : if (!sd)
7204 : return target;
7205 :
7206 : if (sched_smt_active()) {
7207 : has_idle_core = test_idle_cores(target);
7208 :
7209 : if (!has_idle_core && cpus_share_cache(prev, target)) {
7210 : i = select_idle_smt(p, prev);
7211 : if ((unsigned int)i < nr_cpumask_bits)
7212 : return i;
7213 : }
7214 : }
7215 :
7216 : i = select_idle_cpu(p, sd, has_idle_core, target);
7217 : if ((unsigned)i < nr_cpumask_bits)
7218 : return i;
7219 :
7220 : return target;
7221 : }
7222 :
7223 : /**
7224 : * cpu_util() - Estimates the amount of CPU capacity used by CFS tasks.
7225 : * @cpu: the CPU to get the utilization for
7226 : * @p: task for which the CPU utilization should be predicted or NULL
7227 : * @dst_cpu: CPU @p migrates to, -1 if @p moves from @cpu or @p == NULL
7228 : * @boost: 1 to enable boosting, otherwise 0
7229 : *
7230 : * The unit of the return value must be the same as the one of CPU capacity
7231 : * so that CPU utilization can be compared with CPU capacity.
7232 : *
7233 : * CPU utilization is the sum of running time of runnable tasks plus the
7234 : * recent utilization of currently non-runnable tasks on that CPU.
7235 : * It represents the amount of CPU capacity currently used by CFS tasks in
7236 : * the range [0..max CPU capacity] with max CPU capacity being the CPU
7237 : * capacity at f_max.
7238 : *
7239 : * The estimated CPU utilization is defined as the maximum between CPU
7240 : * utilization and sum of the estimated utilization of the currently
7241 : * runnable tasks on that CPU. It preserves a utilization "snapshot" of
7242 : * previously-executed tasks, which helps better deduce how busy a CPU will
7243 : * be when a long-sleeping task wakes up. The contribution to CPU utilization
7244 : * of such a task would be significantly decayed at this point of time.
7245 : *
7246 : * Boosted CPU utilization is defined as max(CPU runnable, CPU utilization).
7247 : * CPU contention for CFS tasks can be detected by CPU runnable > CPU
7248 : * utilization. Boosting is implemented in cpu_util() so that internal
7249 : * users (e.g. EAS) can use it next to external users (e.g. schedutil),
7250 : * latter via cpu_util_cfs_boost().
7251 : *
7252 : * CPU utilization can be higher than the current CPU capacity
7253 : * (f_curr/f_max * max CPU capacity) or even the max CPU capacity because
7254 : * of rounding errors as well as task migrations or wakeups of new tasks.
7255 : * CPU utilization has to be capped to fit into the [0..max CPU capacity]
7256 : * range. Otherwise a group of CPUs (CPU0 util = 121% + CPU1 util = 80%)
7257 : * could be seen as over-utilized even though CPU1 has 20% of spare CPU
7258 : * capacity. CPU utilization is allowed to overshoot current CPU capacity
7259 : * though since this is useful for predicting the CPU capacity required
7260 : * after task migrations (scheduler-driven DVFS).
7261 : *
7262 : * Return: (Boosted) (estimated) utilization for the specified CPU.
7263 : */
7264 : static unsigned long
7265 : cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
7266 : {
7267 : struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
7268 : unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
7269 : unsigned long runnable;
7270 :
7271 : if (boost) {
7272 : runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
7273 : util = max(util, runnable);
7274 : }
7275 :
7276 : /*
7277 : * If @dst_cpu is -1 or @p migrates from @cpu to @dst_cpu remove its
7278 : * contribution. If @p migrates from another CPU to @cpu add its
7279 : * contribution. In all the other cases @cpu is not impacted by the
7280 : * migration so its util_avg is already correct.
7281 : */
7282 : if (p && task_cpu(p) == cpu && dst_cpu != cpu)
7283 : lsub_positive(&util, task_util(p));
7284 : else if (p && task_cpu(p) != cpu && dst_cpu == cpu)
7285 : util += task_util(p);
7286 :
7287 : if (sched_feat(UTIL_EST)) {
7288 : unsigned long util_est;
7289 :
7290 : util_est = READ_ONCE(cfs_rq->avg.util_est.enqueued);
7291 :
7292 : if (boost)
7293 : util_est = max(util_est, runnable);
7294 :
7295 : /*
7296 : * During wake-up @p isn't enqueued yet and doesn't contribute
7297 : * to any cpu_rq(cpu)->cfs.avg.util_est.enqueued.
7298 : * If @dst_cpu == @cpu add it to "simulate" cpu_util after @p
7299 : * has been enqueued.
7300 : *
7301 : * During exec (@dst_cpu = -1) @p is enqueued and does
7302 : * contribute to cpu_rq(cpu)->cfs.util_est.enqueued.
7303 : * Remove it to "simulate" cpu_util without @p's contribution.
7304 : *
7305 : * Despite the task_on_rq_queued(@p) check there is still a
7306 : * small window for a possible race when an exec
7307 : * select_task_rq_fair() races with LB's detach_task().
7308 : *
7309 : * detach_task()
7310 : * deactivate_task()
7311 : * p->on_rq = TASK_ON_RQ_MIGRATING;
7312 : * -------------------------------- A
7313 : * dequeue_task() \
7314 : * dequeue_task_fair() + Race Time
7315 : * util_est_dequeue() /
7316 : * -------------------------------- B
7317 : *
7318 : * The additional check "current == p" is required to further
7319 : * reduce the race window.
7320 : */
7321 : if (dst_cpu == cpu)
7322 : util_est += _task_util_est(p);
7323 : else if (p && unlikely(task_on_rq_queued(p) || current == p))
7324 : lsub_positive(&util_est, _task_util_est(p));
7325 :
7326 : util = max(util, util_est);
7327 : }
7328 :
7329 : return min(util, capacity_orig_of(cpu));
7330 : }
7331 :
7332 : unsigned long cpu_util_cfs(int cpu)
7333 : {
7334 : return cpu_util(cpu, NULL, -1, 0);
7335 : }
7336 :
7337 : unsigned long cpu_util_cfs_boost(int cpu)
7338 : {
7339 : return cpu_util(cpu, NULL, -1, 1);
7340 : }
7341 :
7342 : /*
7343 : * cpu_util_without: compute cpu utilization without any contributions from *p
7344 : * @cpu: the CPU which utilization is requested
7345 : * @p: the task which utilization should be discounted
7346 : *
7347 : * The utilization of a CPU is defined by the utilization of tasks currently
7348 : * enqueued on that CPU as well as tasks which are currently sleeping after an
7349 : * execution on that CPU.
7350 : *
7351 : * This method returns the utilization of the specified CPU by discounting the
7352 : * utilization of the specified task, whenever the task is currently
7353 : * contributing to the CPU utilization.
7354 : */
7355 : static unsigned long cpu_util_without(int cpu, struct task_struct *p)
7356 : {
7357 : /* Task has no contribution or is new */
7358 : if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
7359 : p = NULL;
7360 :
7361 : return cpu_util(cpu, p, -1, 0);
7362 : }
7363 :
7364 : /*
7365 : * energy_env - Utilization landscape for energy estimation.
7366 : * @task_busy_time: Utilization contribution by the task for which we test the
7367 : * placement. Given by eenv_task_busy_time().
7368 : * @pd_busy_time: Utilization of the whole perf domain without the task
7369 : * contribution. Given by eenv_pd_busy_time().
7370 : * @cpu_cap: Maximum CPU capacity for the perf domain.
7371 : * @pd_cap: Entire perf domain capacity. (pd->nr_cpus * cpu_cap).
7372 : */
7373 : struct energy_env {
7374 : unsigned long task_busy_time;
7375 : unsigned long pd_busy_time;
7376 : unsigned long cpu_cap;
7377 : unsigned long pd_cap;
7378 : };
7379 :
7380 : /*
7381 : * Compute the task busy time for compute_energy(). This time cannot be
7382 : * injected directly into effective_cpu_util() because of the IRQ scaling.
7383 : * The latter only makes sense with the most recent CPUs where the task has
7384 : * run.
7385 : */
7386 : static inline void eenv_task_busy_time(struct energy_env *eenv,
7387 : struct task_struct *p, int prev_cpu)
7388 : {
7389 : unsigned long busy_time, max_cap = arch_scale_cpu_capacity(prev_cpu);
7390 : unsigned long irq = cpu_util_irq(cpu_rq(prev_cpu));
7391 :
7392 : if (unlikely(irq >= max_cap))
7393 : busy_time = max_cap;
7394 : else
7395 : busy_time = scale_irq_capacity(task_util_est(p), irq, max_cap);
7396 :
7397 : eenv->task_busy_time = busy_time;
7398 : }
7399 :
7400 : /*
7401 : * Compute the perf_domain (PD) busy time for compute_energy(). Based on the
7402 : * utilization for each @pd_cpus, it however doesn't take into account
7403 : * clamping since the ratio (utilization / cpu_capacity) is already enough to
7404 : * scale the EM reported power consumption at the (eventually clamped)
7405 : * cpu_capacity.
7406 : *
7407 : * The contribution of the task @p for which we want to estimate the
7408 : * energy cost is removed (by cpu_util()) and must be calculated
7409 : * separately (see eenv_task_busy_time). This ensures:
7410 : *
7411 : * - A stable PD utilization, no matter which CPU of that PD we want to place
7412 : * the task on.
7413 : *
7414 : * - A fair comparison between CPUs as the task contribution (task_util())
7415 : * will always be the same no matter which CPU utilization we rely on
7416 : * (util_avg or util_est).
7417 : *
7418 : * Set @eenv busy time for the PD that spans @pd_cpus. This busy time can't
7419 : * exceed @eenv->pd_cap.
7420 : */
7421 : static inline void eenv_pd_busy_time(struct energy_env *eenv,
7422 : struct cpumask *pd_cpus,
7423 : struct task_struct *p)
7424 : {
7425 : unsigned long busy_time = 0;
7426 : int cpu;
7427 :
7428 : for_each_cpu(cpu, pd_cpus) {
7429 : unsigned long util = cpu_util(cpu, p, -1, 0);
7430 :
7431 : busy_time += effective_cpu_util(cpu, util, ENERGY_UTIL, NULL);
7432 : }
7433 :
7434 : eenv->pd_busy_time = min(eenv->pd_cap, busy_time);
7435 : }
7436 :
7437 : /*
7438 : * Compute the maximum utilization for compute_energy() when the task @p
7439 : * is placed on the cpu @dst_cpu.
7440 : *
7441 : * Returns the maximum utilization among @eenv->cpus. This utilization can't
7442 : * exceed @eenv->cpu_cap.
7443 : */
7444 : static inline unsigned long
7445 : eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
7446 : struct task_struct *p, int dst_cpu)
7447 : {
7448 : unsigned long max_util = 0;
7449 : int cpu;
7450 :
7451 : for_each_cpu(cpu, pd_cpus) {
7452 : struct task_struct *tsk = (cpu == dst_cpu) ? p : NULL;
7453 : unsigned long util = cpu_util(cpu, p, dst_cpu, 1);
7454 : unsigned long eff_util;
7455 :
7456 : /*
7457 : * Performance domain frequency: utilization clamping
7458 : * must be considered since it affects the selection
7459 : * of the performance domain frequency.
7460 : * NOTE: in case RT tasks are running, by default the
7461 : * FREQUENCY_UTIL's utilization can be max OPP.
7462 : */
7463 : eff_util = effective_cpu_util(cpu, util, FREQUENCY_UTIL, tsk);
7464 : max_util = max(max_util, eff_util);
7465 : }
7466 :
7467 : return min(max_util, eenv->cpu_cap);
7468 : }
7469 :
7470 : /*
7471 : * compute_energy(): Use the Energy Model to estimate the energy that @pd would
7472 : * consume for a given utilization landscape @eenv. When @dst_cpu < 0, the task
7473 : * contribution is ignored.
7474 : */
7475 : static inline unsigned long
7476 : compute_energy(struct energy_env *eenv, struct perf_domain *pd,
7477 : struct cpumask *pd_cpus, struct task_struct *p, int dst_cpu)
7478 : {
7479 : unsigned long max_util = eenv_pd_max_util(eenv, pd_cpus, p, dst_cpu);
7480 : unsigned long busy_time = eenv->pd_busy_time;
7481 :
7482 : if (dst_cpu >= 0)
7483 : busy_time = min(eenv->pd_cap, busy_time + eenv->task_busy_time);
7484 :
7485 : return em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
7486 : }
7487 :
7488 : /*
7489 : * find_energy_efficient_cpu(): Find most energy-efficient target CPU for the
7490 : * waking task. find_energy_efficient_cpu() looks for the CPU with maximum
7491 : * spare capacity in each performance domain and uses it as a potential
7492 : * candidate to execute the task. Then, it uses the Energy Model to figure
7493 : * out which of the CPU candidates is the most energy-efficient.
7494 : *
7495 : * The rationale for this heuristic is as follows. In a performance domain,
7496 : * all the most energy efficient CPU candidates (according to the Energy
7497 : * Model) are those for which we'll request a low frequency. When there are
7498 : * several CPUs for which the frequency request will be the same, we don't
7499 : * have enough data to break the tie between them, because the Energy Model
7500 : * only includes active power costs. With this model, if we assume that
7501 : * frequency requests follow utilization (e.g. using schedutil), the CPU with
7502 : * the maximum spare capacity in a performance domain is guaranteed to be among
7503 : * the best candidates of the performance domain.
7504 : *
7505 : * In practice, it could be preferable from an energy standpoint to pack
7506 : * small tasks on a CPU in order to let other CPUs go in deeper idle states,
7507 : * but that could also hurt our chances to go cluster idle, and we have no
7508 : * ways to tell with the current Energy Model if this is actually a good
7509 : * idea or not. So, find_energy_efficient_cpu() basically favors
7510 : * cluster-packing, and spreading inside a cluster. That should at least be
7511 : * a good thing for latency, and this is consistent with the idea that most
7512 : * of the energy savings of EAS come from the asymmetry of the system, and
7513 : * not so much from breaking the tie between identical CPUs. That's also the
7514 : * reason why EAS is enabled in the topology code only for systems where
7515 : * SD_ASYM_CPUCAPACITY is set.
7516 : *
7517 : * NOTE: Forkees are not accepted in the energy-aware wake-up path because
7518 : * they don't have any useful utilization data yet and it's not possible to
7519 : * forecast their impact on energy consumption. Consequently, they will be
7520 : * placed by find_idlest_cpu() on the least loaded CPU, which might turn out
7521 : * to be energy-inefficient in some use-cases. The alternative would be to
7522 : * bias new tasks towards specific types of CPUs first, or to try to infer
7523 : * their util_avg from the parent task, but those heuristics could hurt
7524 : * other use-cases too. So, until someone finds a better way to solve this,
7525 : * let's keep things simple by re-using the existing slow path.
7526 : */
7527 : static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
7528 : {
7529 : struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
7530 : unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
7531 : unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0;
7532 : unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024;
7533 : struct root_domain *rd = this_rq()->rd;
7534 : int cpu, best_energy_cpu, target = -1;
7535 : int prev_fits = -1, best_fits = -1;
7536 : unsigned long best_thermal_cap = 0;
7537 : unsigned long prev_thermal_cap = 0;
7538 : struct sched_domain *sd;
7539 : struct perf_domain *pd;
7540 : struct energy_env eenv;
7541 :
7542 : rcu_read_lock();
7543 : pd = rcu_dereference(rd->pd);
7544 : if (!pd || READ_ONCE(rd->overutilized))
7545 : goto unlock;
7546 :
7547 : /*
7548 : * Energy-aware wake-up happens on the lowest sched_domain starting
7549 : * from sd_asym_cpucapacity spanning over this_cpu and prev_cpu.
7550 : */
7551 : sd = rcu_dereference(*this_cpu_ptr(&sd_asym_cpucapacity));
7552 : while (sd && !cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
7553 : sd = sd->parent;
7554 : if (!sd)
7555 : goto unlock;
7556 :
7557 : target = prev_cpu;
7558 :
7559 : sync_entity_load_avg(&p->se);
7560 : if (!uclamp_task_util(p, p_util_min, p_util_max))
7561 : goto unlock;
7562 :
7563 : eenv_task_busy_time(&eenv, p, prev_cpu);
7564 :
7565 : for (; pd; pd = pd->next) {
7566 : unsigned long util_min = p_util_min, util_max = p_util_max;
7567 : unsigned long cpu_cap, cpu_thermal_cap, util;
7568 : unsigned long cur_delta, max_spare_cap = 0;
7569 : unsigned long rq_util_min, rq_util_max;
7570 : unsigned long prev_spare_cap = 0;
7571 : int max_spare_cap_cpu = -1;
7572 : unsigned long base_energy;
7573 : int fits, max_fits = -1;
7574 :
7575 : cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask);
7576 :
7577 : if (cpumask_empty(cpus))
7578 : continue;
7579 :
7580 : /* Account thermal pressure for the energy estimation */
7581 : cpu = cpumask_first(cpus);
7582 : cpu_thermal_cap = arch_scale_cpu_capacity(cpu);
7583 : cpu_thermal_cap -= arch_scale_thermal_pressure(cpu);
7584 :
7585 : eenv.cpu_cap = cpu_thermal_cap;
7586 : eenv.pd_cap = 0;
7587 :
7588 : for_each_cpu(cpu, cpus) {
7589 : struct rq *rq = cpu_rq(cpu);
7590 :
7591 : eenv.pd_cap += cpu_thermal_cap;
7592 :
7593 : if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
7594 : continue;
7595 :
7596 : if (!cpumask_test_cpu(cpu, p->cpus_ptr))
7597 : continue;
7598 :
7599 : util = cpu_util(cpu, p, cpu, 0);
7600 : cpu_cap = capacity_of(cpu);
7601 :
7602 : /*
7603 : * Skip CPUs that cannot satisfy the capacity request.
7604 : * IOW, placing the task there would make the CPU
7605 : * overutilized. Take uclamp into account to see how
7606 : * much capacity we can get out of the CPU; this is
7607 : * aligned with sched_cpu_util().
7608 : */
7609 : if (uclamp_is_used() && !uclamp_rq_is_idle(rq)) {
7610 : /*
7611 : * Open code uclamp_rq_util_with() except for
7612 : * the clamp() part. Ie: apply max aggregation
7613 : * only. util_fits_cpu() logic requires to
7614 : * operate on non clamped util but must use the
7615 : * max-aggregated uclamp_{min, max}.
7616 : */
7617 : rq_util_min = uclamp_rq_get(rq, UCLAMP_MIN);
7618 : rq_util_max = uclamp_rq_get(rq, UCLAMP_MAX);
7619 :
7620 : util_min = max(rq_util_min, p_util_min);
7621 : util_max = max(rq_util_max, p_util_max);
7622 : }
7623 :
7624 : fits = util_fits_cpu(util, util_min, util_max, cpu);
7625 : if (!fits)
7626 : continue;
7627 :
7628 : lsub_positive(&cpu_cap, util);
7629 :
7630 : if (cpu == prev_cpu) {
7631 : /* Always use prev_cpu as a candidate. */
7632 : prev_spare_cap = cpu_cap;
7633 : prev_fits = fits;
7634 : } else if ((fits > max_fits) ||
7635 : ((fits == max_fits) && (cpu_cap > max_spare_cap))) {
7636 : /*
7637 : * Find the CPU with the maximum spare capacity
7638 : * among the remaining CPUs in the performance
7639 : * domain.
7640 : */
7641 : max_spare_cap = cpu_cap;
7642 : max_spare_cap_cpu = cpu;
7643 : max_fits = fits;
7644 : }
7645 : }
7646 :
7647 : if (max_spare_cap_cpu < 0 && prev_spare_cap == 0)
7648 : continue;
7649 :
7650 : eenv_pd_busy_time(&eenv, cpus, p);
7651 : /* Compute the 'base' energy of the pd, without @p */
7652 : base_energy = compute_energy(&eenv, pd, cpus, p, -1);
7653 :
7654 : /* Evaluate the energy impact of using prev_cpu. */
7655 : if (prev_spare_cap > 0) {
7656 : prev_delta = compute_energy(&eenv, pd, cpus, p,
7657 : prev_cpu);
7658 : /* CPU utilization has changed */
7659 : if (prev_delta < base_energy)
7660 : goto unlock;
7661 : prev_delta -= base_energy;
7662 : prev_thermal_cap = cpu_thermal_cap;
7663 : best_delta = min(best_delta, prev_delta);
7664 : }
7665 :
7666 : /* Evaluate the energy impact of using max_spare_cap_cpu. */
7667 : if (max_spare_cap_cpu >= 0 && max_spare_cap > prev_spare_cap) {
7668 : /* Current best energy cpu fits better */
7669 : if (max_fits < best_fits)
7670 : continue;
7671 :
7672 : /*
7673 : * Both don't fit performance hint (i.e. uclamp_min)
7674 : * but best energy cpu has better capacity.
7675 : */
7676 : if ((max_fits < 0) &&
7677 : (cpu_thermal_cap <= best_thermal_cap))
7678 : continue;
7679 :
7680 : cur_delta = compute_energy(&eenv, pd, cpus, p,
7681 : max_spare_cap_cpu);
7682 : /* CPU utilization has changed */
7683 : if (cur_delta < base_energy)
7684 : goto unlock;
7685 : cur_delta -= base_energy;
7686 :
7687 : /*
7688 : * Both fit for the task but best energy cpu has lower
7689 : * energy impact.
7690 : */
7691 : if ((max_fits > 0) && (best_fits > 0) &&
7692 : (cur_delta >= best_delta))
7693 : continue;
7694 :
7695 : best_delta = cur_delta;
7696 : best_energy_cpu = max_spare_cap_cpu;
7697 : best_fits = max_fits;
7698 : best_thermal_cap = cpu_thermal_cap;
7699 : }
7700 : }
7701 : rcu_read_unlock();
7702 :
7703 : if ((best_fits > prev_fits) ||
7704 : ((best_fits > 0) && (best_delta < prev_delta)) ||
7705 : ((best_fits < 0) && (best_thermal_cap > prev_thermal_cap)))
7706 : target = best_energy_cpu;
7707 :
7708 : return target;
7709 :
7710 : unlock:
7711 : rcu_read_unlock();
7712 :
7713 : return target;
7714 : }
7715 :
7716 : /*
7717 : * select_task_rq_fair: Select target runqueue for the waking task in domains
7718 : * that have the relevant SD flag set. In practice, this is SD_BALANCE_WAKE,
7719 : * SD_BALANCE_FORK, or SD_BALANCE_EXEC.
7720 : *
7721 : * Balances load by selecting the idlest CPU in the idlest group, or under
7722 : * certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
7723 : *
7724 : * Returns the target CPU number.
7725 : */
7726 : static int
7727 : select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
7728 : {
7729 : int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
7730 : struct sched_domain *tmp, *sd = NULL;
7731 : int cpu = smp_processor_id();
7732 : int new_cpu = prev_cpu;
7733 : int want_affine = 0;
7734 : /* SD_flags and WF_flags share the first nibble */
7735 : int sd_flag = wake_flags & 0xF;
7736 :
7737 : /*
7738 : * required for stable ->cpus_allowed
7739 : */
7740 : lockdep_assert_held(&p->pi_lock);
7741 : if (wake_flags & WF_TTWU) {
7742 : record_wakee(p);
7743 :
7744 : if (sched_energy_enabled()) {
7745 : new_cpu = find_energy_efficient_cpu(p, prev_cpu);
7746 : if (new_cpu >= 0)
7747 : return new_cpu;
7748 : new_cpu = prev_cpu;
7749 : }
7750 :
7751 : want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr);
7752 : }
7753 :
7754 : rcu_read_lock();
7755 : for_each_domain(cpu, tmp) {
7756 : /*
7757 : * If both 'cpu' and 'prev_cpu' are part of this domain,
7758 : * cpu is a valid SD_WAKE_AFFINE target.
7759 : */
7760 : if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
7761 : cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
7762 : if (cpu != prev_cpu)
7763 : new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
7764 :
7765 : sd = NULL; /* Prefer wake_affine over balance flags */
7766 : break;
7767 : }
7768 :
7769 : /*
7770 : * Usually only true for WF_EXEC and WF_FORK, as sched_domains
7771 : * usually do not have SD_BALANCE_WAKE set. That means wakeup
7772 : * will usually go to the fast path.
7773 : */
7774 : if (tmp->flags & sd_flag)
7775 : sd = tmp;
7776 : else if (!want_affine)
7777 : break;
7778 : }
7779 :
7780 : if (unlikely(sd)) {
7781 : /* Slow path */
7782 : new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
7783 : } else if (wake_flags & WF_TTWU) { /* XXX always ? */
7784 : /* Fast path */
7785 : new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
7786 : }
7787 : rcu_read_unlock();
7788 :
7789 : return new_cpu;
7790 : }
7791 :
7792 : /*
7793 : * Called immediately before a task is migrated to a new CPU; task_cpu(p) and
7794 : * cfs_rq_of(p) references at time of call are still valid and identify the
7795 : * previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
7796 : */
7797 : static void migrate_task_rq_fair(struct task_struct *p, int new_cpu)
7798 : {
7799 : struct sched_entity *se = &p->se;
7800 :
7801 : /*
7802 : * As blocked tasks retain absolute vruntime the migration needs to
7803 : * deal with this by subtracting the old and adding the new
7804 : * min_vruntime -- the latter is done by enqueue_entity() when placing
7805 : * the task on the new runqueue.
7806 : */
7807 : if (READ_ONCE(p->__state) == TASK_WAKING) {
7808 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
7809 :
7810 : se->vruntime -= u64_u32_load(cfs_rq->min_vruntime);
7811 : }
7812 :
7813 : if (!task_on_rq_migrating(p)) {
7814 : remove_entity_load_avg(se);
7815 :
7816 : /*
7817 : * Here, the task's PELT values have been updated according to
7818 : * the current rq's clock. But if that clock hasn't been
7819 : * updated in a while, a substantial idle time will be missed,
7820 : * leading to an inflation after wake-up on the new rq.
7821 : *
7822 : * Estimate the missing time from the cfs_rq last_update_time
7823 : * and update sched_avg to improve the PELT continuity after
7824 : * migration.
7825 : */
7826 : migrate_se_pelt_lag(se);
7827 : }
7828 :
7829 : /* Tell new CPU we are migrated */
7830 : se->avg.last_update_time = 0;
7831 :
7832 : update_scan_period(p, new_cpu);
7833 : }
7834 :
7835 : static void task_dead_fair(struct task_struct *p)
7836 : {
7837 : remove_entity_load_avg(&p->se);
7838 : }
7839 :
7840 : static int
7841 : balance_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
7842 : {
7843 : if (rq->nr_running)
7844 : return 1;
7845 :
7846 : return newidle_balance(rq, rf) != 0;
7847 : }
7848 : #endif /* CONFIG_SMP */
7849 :
7850 : static unsigned long wakeup_gran(struct sched_entity *se)
7851 : {
7852 338 : unsigned long gran = sysctl_sched_wakeup_granularity;
7853 :
7854 : /*
7855 : * Since its curr running now, convert the gran from real-time
7856 : * to virtual-time in his units.
7857 : *
7858 : * By using 'se' instead of 'curr' we penalize light tasks, so
7859 : * they get preempted easier. That is, if 'se' < 'curr' then
7860 : * the resulting gran will be larger, therefore penalizing the
7861 : * lighter, if otoh 'se' > 'curr' then the resulting gran will
7862 : * be smaller, again penalizing the lighter task.
7863 : *
7864 : * This is especially important for buddies when the leftmost
7865 : * task is higher priority than the buddy.
7866 : */
7867 338 : return calc_delta_fair(gran, se);
7868 : }
7869 :
7870 : /*
7871 : * Should 'se' preempt 'curr'.
7872 : *
7873 : * |s1
7874 : * |s2
7875 : * |s3
7876 : * g
7877 : * |<--->|c
7878 : *
7879 : * w(c, s1) = -1
7880 : * w(c, s2) = 0
7881 : * w(c, s3) = 1
7882 : *
7883 : */
7884 : static int
7885 1198 : wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
7886 : {
7887 1198 : s64 gran, vdiff = curr->vruntime - se->vruntime;
7888 :
7889 1198 : if (vdiff <= 0)
7890 : return -1;
7891 :
7892 338 : gran = wakeup_gran(se);
7893 338 : if (vdiff > gran)
7894 : return 1;
7895 :
7896 : return 0;
7897 : }
7898 :
7899 : static void set_last_buddy(struct sched_entity *se)
7900 : {
7901 0 : for_each_sched_entity(se) {
7902 : if (SCHED_WARN_ON(!se->on_rq))
7903 : return;
7904 0 : if (se_is_idle(se))
7905 : return;
7906 0 : cfs_rq_of(se)->last = se;
7907 : }
7908 : }
7909 :
7910 : static void set_next_buddy(struct sched_entity *se)
7911 : {
7912 336 : for_each_sched_entity(se) {
7913 : if (SCHED_WARN_ON(!se->on_rq))
7914 : return;
7915 336 : if (se_is_idle(se))
7916 : return;
7917 672 : cfs_rq_of(se)->next = se;
7918 : }
7919 : }
7920 :
7921 : static void set_skip_buddy(struct sched_entity *se)
7922 : {
7923 0 : for_each_sched_entity(se)
7924 0 : cfs_rq_of(se)->skip = se;
7925 : }
7926 :
7927 : /*
7928 : * Preempt the current task with a newly woken task if needed:
7929 : */
7930 1028 : static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
7931 : {
7932 1028 : struct task_struct *curr = rq->curr;
7933 1028 : struct sched_entity *se = &curr->se, *pse = &p->se;
7934 2056 : struct cfs_rq *cfs_rq = task_cfs_rq(curr);
7935 1028 : int scale = cfs_rq->nr_running >= sched_nr_latency;
7936 1028 : int next_buddy_marked = 0;
7937 : int cse_is_idle, pse_is_idle;
7938 :
7939 1028 : if (unlikely(se == pse))
7940 : return;
7941 :
7942 : /*
7943 : * This is possible from callers such as attach_tasks(), in which we
7944 : * unconditionally check_preempt_curr() after an enqueue (which may have
7945 : * lead to a throttle). This both saves work and prevents false
7946 : * next-buddy nomination below.
7947 : */
7948 1028 : if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
7949 : return;
7950 :
7951 : if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
7952 : set_next_buddy(pse);
7953 : next_buddy_marked = 1;
7954 : }
7955 :
7956 : /*
7957 : * We can come here with TIF_NEED_RESCHED already set from new task
7958 : * wake up path.
7959 : *
7960 : * Note: this also catches the edge-case of curr being in a throttled
7961 : * group (e.g. via set_curr_task), since update_curr() (in the
7962 : * enqueue of curr) will have resulted in resched being set. This
7963 : * prevents us from potentially nominating it as a false LAST_BUDDY
7964 : * below.
7965 : */
7966 1028 : if (test_tsk_need_resched(curr))
7967 : return;
7968 :
7969 : /* Idle tasks are by definition preempted by non-idle tasks. */
7970 1724 : if (unlikely(task_has_idle_policy(curr)) &&
7971 0 : likely(!task_has_idle_policy(p)))
7972 : goto preempt;
7973 :
7974 : /*
7975 : * Batch and idle tasks do not preempt non-idle tasks (their preemption
7976 : * is driven by the tick):
7977 : */
7978 862 : if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
7979 : return;
7980 :
7981 862 : find_matching_se(&se, &pse);
7982 862 : WARN_ON_ONCE(!pse);
7983 :
7984 862 : cse_is_idle = se_is_idle(se);
7985 862 : pse_is_idle = se_is_idle(pse);
7986 :
7987 : /*
7988 : * Preempt an idle group in favor of a non-idle group (and don't preempt
7989 : * in the inverse case).
7990 : */
7991 : if (cse_is_idle && !pse_is_idle)
7992 : goto preempt;
7993 : if (cse_is_idle != pse_is_idle)
7994 : return;
7995 :
7996 1724 : update_curr(cfs_rq_of(se));
7997 862 : if (wakeup_preempt_entity(se, pse) == 1) {
7998 : /*
7999 : * Bias pick_next to pick the sched entity that is
8000 : * triggering this preemption.
8001 : */
8002 : if (!next_buddy_marked)
8003 : set_next_buddy(pse);
8004 : goto preempt;
8005 : }
8006 :
8007 : return;
8008 :
8009 : preempt:
8010 336 : resched_curr(rq);
8011 : /*
8012 : * Only set the backward buddy when the current task is still
8013 : * on the rq. This can happen when a wakeup gets interleaved
8014 : * with schedule on the ->pre_schedule() or idle_balance()
8015 : * point, either of which can * drop the rq lock.
8016 : *
8017 : * Also, during early boot the idle thread is in the fair class,
8018 : * for obvious reasons its a bad idea to schedule back to it.
8019 : */
8020 336 : if (unlikely(!se->on_rq || curr == rq->idle))
8021 : return;
8022 :
8023 336 : if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
8024 : set_last_buddy(se);
8025 : }
8026 :
8027 : #ifdef CONFIG_SMP
8028 : static struct task_struct *pick_task_fair(struct rq *rq)
8029 : {
8030 : struct sched_entity *se;
8031 : struct cfs_rq *cfs_rq;
8032 :
8033 : again:
8034 : cfs_rq = &rq->cfs;
8035 : if (!cfs_rq->nr_running)
8036 : return NULL;
8037 :
8038 : do {
8039 : struct sched_entity *curr = cfs_rq->curr;
8040 :
8041 : /* When we pick for a remote RQ, we'll not have done put_prev_entity() */
8042 : if (curr) {
8043 : if (curr->on_rq)
8044 : update_curr(cfs_rq);
8045 : else
8046 : curr = NULL;
8047 :
8048 : if (unlikely(check_cfs_rq_runtime(cfs_rq)))
8049 : goto again;
8050 : }
8051 :
8052 : se = pick_next_entity(cfs_rq, curr);
8053 : cfs_rq = group_cfs_rq(se);
8054 : } while (cfs_rq);
8055 :
8056 : return task_of(se);
8057 : }
8058 : #endif
8059 :
8060 : struct task_struct *
8061 1032 : pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
8062 : {
8063 1032 : struct cfs_rq *cfs_rq = &rq->cfs;
8064 : struct sched_entity *se;
8065 : struct task_struct *p;
8066 : int new_tasks;
8067 :
8068 : again:
8069 1032 : if (!sched_fair_runnable(rq))
8070 : goto idle;
8071 :
8072 : #ifdef CONFIG_FAIR_GROUP_SCHED
8073 : if (!prev || prev->sched_class != &fair_sched_class)
8074 : goto simple;
8075 :
8076 : /*
8077 : * Because of the set_next_buddy() in dequeue_task_fair() it is rather
8078 : * likely that a next task is from the same cgroup as the current.
8079 : *
8080 : * Therefore attempt to avoid putting and setting the entire cgroup
8081 : * hierarchy, only change the part that actually changes.
8082 : */
8083 :
8084 : do {
8085 : struct sched_entity *curr = cfs_rq->curr;
8086 :
8087 : /*
8088 : * Since we got here without doing put_prev_entity() we also
8089 : * have to consider cfs_rq->curr. If it is still a runnable
8090 : * entity, update_curr() will update its vruntime, otherwise
8091 : * forget we've ever seen it.
8092 : */
8093 : if (curr) {
8094 : if (curr->on_rq)
8095 : update_curr(cfs_rq);
8096 : else
8097 : curr = NULL;
8098 :
8099 : /*
8100 : * This call to check_cfs_rq_runtime() will do the
8101 : * throttle and dequeue its entity in the parent(s).
8102 : * Therefore the nr_running test will indeed
8103 : * be correct.
8104 : */
8105 : if (unlikely(check_cfs_rq_runtime(cfs_rq))) {
8106 : cfs_rq = &rq->cfs;
8107 :
8108 : if (!cfs_rq->nr_running)
8109 : goto idle;
8110 :
8111 : goto simple;
8112 : }
8113 : }
8114 :
8115 : se = pick_next_entity(cfs_rq, curr);
8116 : cfs_rq = group_cfs_rq(se);
8117 : } while (cfs_rq);
8118 :
8119 : p = task_of(se);
8120 :
8121 : /*
8122 : * Since we haven't yet done put_prev_entity and if the selected task
8123 : * is a different task than we started out with, try and touch the
8124 : * least amount of cfs_rqs.
8125 : */
8126 : if (prev != p) {
8127 : struct sched_entity *pse = &prev->se;
8128 :
8129 : while (!(cfs_rq = is_same_group(se, pse))) {
8130 : int se_depth = se->depth;
8131 : int pse_depth = pse->depth;
8132 :
8133 : if (se_depth <= pse_depth) {
8134 : put_prev_entity(cfs_rq_of(pse), pse);
8135 : pse = parent_entity(pse);
8136 : }
8137 : if (se_depth >= pse_depth) {
8138 : set_next_entity(cfs_rq_of(se), se);
8139 : se = parent_entity(se);
8140 : }
8141 : }
8142 :
8143 : put_prev_entity(cfs_rq, pse);
8144 : set_next_entity(cfs_rq, se);
8145 : }
8146 :
8147 : goto done;
8148 : simple:
8149 : #endif
8150 1030 : if (prev)
8151 1030 : put_prev_task(rq, prev);
8152 :
8153 : do {
8154 1030 : se = pick_next_entity(cfs_rq, NULL);
8155 1030 : set_next_entity(cfs_rq, se);
8156 1030 : cfs_rq = group_cfs_rq(se);
8157 : } while (cfs_rq);
8158 :
8159 1030 : p = task_of(se);
8160 :
8161 : done: __maybe_unused;
8162 : #ifdef CONFIG_SMP
8163 : /*
8164 : * Move the next running task to the front of
8165 : * the list, so our cfs_tasks list becomes MRU
8166 : * one.
8167 : */
8168 : list_move(&p->se.group_node, &rq->cfs_tasks);
8169 : #endif
8170 :
8171 1030 : if (hrtick_enabled_fair(rq))
8172 : hrtick_start_fair(rq, p);
8173 :
8174 1030 : update_misfit_status(p, rq);
8175 :
8176 1030 : return p;
8177 :
8178 : idle:
8179 : if (!rf)
8180 : return NULL;
8181 :
8182 : new_tasks = newidle_balance(rq, rf);
8183 :
8184 : /*
8185 : * Because newidle_balance() releases (and re-acquires) rq->lock, it is
8186 : * possible for any higher priority task to appear. In that case we
8187 : * must re-start the pick_next_entity() loop.
8188 : */
8189 : if (new_tasks < 0)
8190 : return RETRY_TASK;
8191 :
8192 : if (new_tasks > 0)
8193 : goto again;
8194 :
8195 : /*
8196 : * rq is about to be idle, check if we need to update the
8197 : * lost_idle_time of clock_pelt
8198 : */
8199 : update_idle_rq_clock_pelt(rq);
8200 :
8201 : return NULL;
8202 : }
8203 :
8204 0 : static struct task_struct *__pick_next_task_fair(struct rq *rq)
8205 : {
8206 0 : return pick_next_task_fair(rq, NULL, NULL);
8207 : }
8208 :
8209 : /*
8210 : * Account for a descheduled task:
8211 : */
8212 1033 : static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
8213 : {
8214 1033 : struct sched_entity *se = &prev->se;
8215 : struct cfs_rq *cfs_rq;
8216 :
8217 2066 : for_each_sched_entity(se) {
8218 2066 : cfs_rq = cfs_rq_of(se);
8219 1033 : put_prev_entity(cfs_rq, se);
8220 : }
8221 1033 : }
8222 :
8223 : /*
8224 : * sched_yield() is very simple
8225 : *
8226 : * The magic of dealing with the ->skip buddy is in pick_next_entity.
8227 : */
8228 0 : static void yield_task_fair(struct rq *rq)
8229 : {
8230 0 : struct task_struct *curr = rq->curr;
8231 0 : struct cfs_rq *cfs_rq = task_cfs_rq(curr);
8232 0 : struct sched_entity *se = &curr->se;
8233 :
8234 : /*
8235 : * Are we the only task in the tree?
8236 : */
8237 0 : if (unlikely(rq->nr_running == 1))
8238 : return;
8239 :
8240 0 : clear_buddies(cfs_rq, se);
8241 :
8242 0 : if (curr->policy != SCHED_BATCH) {
8243 0 : update_rq_clock(rq);
8244 : /*
8245 : * Update run-time statistics of the 'current'.
8246 : */
8247 0 : update_curr(cfs_rq);
8248 : /*
8249 : * Tell update_rq_clock() that we've just updated,
8250 : * so we don't do microscopic update in schedule()
8251 : * and double the fastpath cost.
8252 : */
8253 0 : rq_clock_skip_update(rq);
8254 : }
8255 :
8256 : set_skip_buddy(se);
8257 : }
8258 :
8259 0 : static bool yield_to_task_fair(struct rq *rq, struct task_struct *p)
8260 : {
8261 0 : struct sched_entity *se = &p->se;
8262 :
8263 : /* throttled hierarchies are not runnable */
8264 0 : if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
8265 : return false;
8266 :
8267 : /* Tell the scheduler that we'd really like pse to run next. */
8268 0 : set_next_buddy(se);
8269 :
8270 0 : yield_task_fair(rq);
8271 :
8272 0 : return true;
8273 : }
8274 :
8275 : #ifdef CONFIG_SMP
8276 : /**************************************************
8277 : * Fair scheduling class load-balancing methods.
8278 : *
8279 : * BASICS
8280 : *
8281 : * The purpose of load-balancing is to achieve the same basic fairness the
8282 : * per-CPU scheduler provides, namely provide a proportional amount of compute
8283 : * time to each task. This is expressed in the following equation:
8284 : *
8285 : * W_i,n/P_i == W_j,n/P_j for all i,j (1)
8286 : *
8287 : * Where W_i,n is the n-th weight average for CPU i. The instantaneous weight
8288 : * W_i,0 is defined as:
8289 : *
8290 : * W_i,0 = \Sum_j w_i,j (2)
8291 : *
8292 : * Where w_i,j is the weight of the j-th runnable task on CPU i. This weight
8293 : * is derived from the nice value as per sched_prio_to_weight[].
8294 : *
8295 : * The weight average is an exponential decay average of the instantaneous
8296 : * weight:
8297 : *
8298 : * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
8299 : *
8300 : * C_i is the compute capacity of CPU i, typically it is the
8301 : * fraction of 'recent' time available for SCHED_OTHER task execution. But it
8302 : * can also include other factors [XXX].
8303 : *
8304 : * To achieve this balance we define a measure of imbalance which follows
8305 : * directly from (1):
8306 : *
8307 : * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4)
8308 : *
8309 : * We them move tasks around to minimize the imbalance. In the continuous
8310 : * function space it is obvious this converges, in the discrete case we get
8311 : * a few fun cases generally called infeasible weight scenarios.
8312 : *
8313 : * [XXX expand on:
8314 : * - infeasible weights;
8315 : * - local vs global optima in the discrete case. ]
8316 : *
8317 : *
8318 : * SCHED DOMAINS
8319 : *
8320 : * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
8321 : * for all i,j solution, we create a tree of CPUs that follows the hardware
8322 : * topology where each level pairs two lower groups (or better). This results
8323 : * in O(log n) layers. Furthermore we reduce the number of CPUs going up the
8324 : * tree to only the first of the previous level and we decrease the frequency
8325 : * of load-balance at each level inv. proportional to the number of CPUs in
8326 : * the groups.
8327 : *
8328 : * This yields:
8329 : *
8330 : * log_2 n 1 n
8331 : * \Sum { --- * --- * 2^i } = O(n) (5)
8332 : * i = 0 2^i 2^i
8333 : * `- size of each group
8334 : * | | `- number of CPUs doing load-balance
8335 : * | `- freq
8336 : * `- sum over all levels
8337 : *
8338 : * Coupled with a limit on how many tasks we can migrate every balance pass,
8339 : * this makes (5) the runtime complexity of the balancer.
8340 : *
8341 : * An important property here is that each CPU is still (indirectly) connected
8342 : * to every other CPU in at most O(log n) steps:
8343 : *
8344 : * The adjacency matrix of the resulting graph is given by:
8345 : *
8346 : * log_2 n
8347 : * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
8348 : * k = 0
8349 : *
8350 : * And you'll find that:
8351 : *
8352 : * A^(log_2 n)_i,j != 0 for all i,j (7)
8353 : *
8354 : * Showing there's indeed a path between every CPU in at most O(log n) steps.
8355 : * The task movement gives a factor of O(m), giving a convergence complexity
8356 : * of:
8357 : *
8358 : * O(nm log n), n := nr_cpus, m := nr_tasks (8)
8359 : *
8360 : *
8361 : * WORK CONSERVING
8362 : *
8363 : * In order to avoid CPUs going idle while there's still work to do, new idle
8364 : * balancing is more aggressive and has the newly idle CPU iterate up the domain
8365 : * tree itself instead of relying on other CPUs to bring it work.
8366 : *
8367 : * This adds some complexity to both (5) and (8) but it reduces the total idle
8368 : * time.
8369 : *
8370 : * [XXX more?]
8371 : *
8372 : *
8373 : * CGROUPS
8374 : *
8375 : * Cgroups make a horror show out of (2), instead of a simple sum we get:
8376 : *
8377 : * s_k,i
8378 : * W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
8379 : * S_k
8380 : *
8381 : * Where
8382 : *
8383 : * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
8384 : *
8385 : * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on CPU i.
8386 : *
8387 : * The big problem is S_k, its a global sum needed to compute a local (W_i)
8388 : * property.
8389 : *
8390 : * [XXX write more on how we solve this.. _after_ merging pjt's patches that
8391 : * rewrite all of this once again.]
8392 : */
8393 :
8394 : static unsigned long __read_mostly max_load_balance_interval = HZ/10;
8395 :
8396 : enum fbq_type { regular, remote, all };
8397 :
8398 : /*
8399 : * 'group_type' describes the group of CPUs at the moment of load balancing.
8400 : *
8401 : * The enum is ordered by pulling priority, with the group with lowest priority
8402 : * first so the group_type can simply be compared when selecting the busiest
8403 : * group. See update_sd_pick_busiest().
8404 : */
8405 : enum group_type {
8406 : /* The group has spare capacity that can be used to run more tasks. */
8407 : group_has_spare = 0,
8408 : /*
8409 : * The group is fully used and the tasks don't compete for more CPU
8410 : * cycles. Nevertheless, some tasks might wait before running.
8411 : */
8412 : group_fully_busy,
8413 : /*
8414 : * One task doesn't fit with CPU's capacity and must be migrated to a
8415 : * more powerful CPU.
8416 : */
8417 : group_misfit_task,
8418 : /*
8419 : * SD_ASYM_PACKING only: One local CPU with higher capacity is available,
8420 : * and the task should be migrated to it instead of running on the
8421 : * current CPU.
8422 : */
8423 : group_asym_packing,
8424 : /*
8425 : * The tasks' affinity constraints previously prevented the scheduler
8426 : * from balancing the load across the system.
8427 : */
8428 : group_imbalanced,
8429 : /*
8430 : * The CPU is overloaded and can't provide expected CPU cycles to all
8431 : * tasks.
8432 : */
8433 : group_overloaded
8434 : };
8435 :
8436 : enum migration_type {
8437 : migrate_load = 0,
8438 : migrate_util,
8439 : migrate_task,
8440 : migrate_misfit
8441 : };
8442 :
8443 : #define LBF_ALL_PINNED 0x01
8444 : #define LBF_NEED_BREAK 0x02
8445 : #define LBF_DST_PINNED 0x04
8446 : #define LBF_SOME_PINNED 0x08
8447 : #define LBF_ACTIVE_LB 0x10
8448 :
8449 : struct lb_env {
8450 : struct sched_domain *sd;
8451 :
8452 : struct rq *src_rq;
8453 : int src_cpu;
8454 :
8455 : int dst_cpu;
8456 : struct rq *dst_rq;
8457 :
8458 : struct cpumask *dst_grpmask;
8459 : int new_dst_cpu;
8460 : enum cpu_idle_type idle;
8461 : long imbalance;
8462 : /* The set of CPUs under consideration for load-balancing */
8463 : struct cpumask *cpus;
8464 :
8465 : unsigned int flags;
8466 :
8467 : unsigned int loop;
8468 : unsigned int loop_break;
8469 : unsigned int loop_max;
8470 :
8471 : enum fbq_type fbq_type;
8472 : enum migration_type migration_type;
8473 : struct list_head tasks;
8474 : };
8475 :
8476 : /*
8477 : * Is this task likely cache-hot:
8478 : */
8479 : static int task_hot(struct task_struct *p, struct lb_env *env)
8480 : {
8481 : s64 delta;
8482 :
8483 : lockdep_assert_rq_held(env->src_rq);
8484 :
8485 : if (p->sched_class != &fair_sched_class)
8486 : return 0;
8487 :
8488 : if (unlikely(task_has_idle_policy(p)))
8489 : return 0;
8490 :
8491 : /* SMT siblings share cache */
8492 : if (env->sd->flags & SD_SHARE_CPUCAPACITY)
8493 : return 0;
8494 :
8495 : /*
8496 : * Buddy candidates are cache hot:
8497 : */
8498 : if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running &&
8499 : (&p->se == cfs_rq_of(&p->se)->next ||
8500 : &p->se == cfs_rq_of(&p->se)->last))
8501 : return 1;
8502 :
8503 : if (sysctl_sched_migration_cost == -1)
8504 : return 1;
8505 :
8506 : /*
8507 : * Don't migrate task if the task's cookie does not match
8508 : * with the destination CPU's core cookie.
8509 : */
8510 : if (!sched_core_cookie_match(cpu_rq(env->dst_cpu), p))
8511 : return 1;
8512 :
8513 : if (sysctl_sched_migration_cost == 0)
8514 : return 0;
8515 :
8516 : delta = rq_clock_task(env->src_rq) - p->se.exec_start;
8517 :
8518 : return delta < (s64)sysctl_sched_migration_cost;
8519 : }
8520 :
8521 : #ifdef CONFIG_NUMA_BALANCING
8522 : /*
8523 : * Returns 1, if task migration degrades locality
8524 : * Returns 0, if task migration improves locality i.e migration preferred.
8525 : * Returns -1, if task migration is not affected by locality.
8526 : */
8527 : static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
8528 : {
8529 : struct numa_group *numa_group = rcu_dereference(p->numa_group);
8530 : unsigned long src_weight, dst_weight;
8531 : int src_nid, dst_nid, dist;
8532 :
8533 : if (!static_branch_likely(&sched_numa_balancing))
8534 : return -1;
8535 :
8536 : if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
8537 : return -1;
8538 :
8539 : src_nid = cpu_to_node(env->src_cpu);
8540 : dst_nid = cpu_to_node(env->dst_cpu);
8541 :
8542 : if (src_nid == dst_nid)
8543 : return -1;
8544 :
8545 : /* Migrating away from the preferred node is always bad. */
8546 : if (src_nid == p->numa_preferred_nid) {
8547 : if (env->src_rq->nr_running > env->src_rq->nr_preferred_running)
8548 : return 1;
8549 : else
8550 : return -1;
8551 : }
8552 :
8553 : /* Encourage migration to the preferred node. */
8554 : if (dst_nid == p->numa_preferred_nid)
8555 : return 0;
8556 :
8557 : /* Leaving a core idle is often worse than degrading locality. */
8558 : if (env->idle == CPU_IDLE)
8559 : return -1;
8560 :
8561 : dist = node_distance(src_nid, dst_nid);
8562 : if (numa_group) {
8563 : src_weight = group_weight(p, src_nid, dist);
8564 : dst_weight = group_weight(p, dst_nid, dist);
8565 : } else {
8566 : src_weight = task_weight(p, src_nid, dist);
8567 : dst_weight = task_weight(p, dst_nid, dist);
8568 : }
8569 :
8570 : return dst_weight < src_weight;
8571 : }
8572 :
8573 : #else
8574 : static inline int migrate_degrades_locality(struct task_struct *p,
8575 : struct lb_env *env)
8576 : {
8577 : return -1;
8578 : }
8579 : #endif
8580 :
8581 : /*
8582 : * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
8583 : */
8584 : static
8585 : int can_migrate_task(struct task_struct *p, struct lb_env *env)
8586 : {
8587 : int tsk_cache_hot;
8588 :
8589 : lockdep_assert_rq_held(env->src_rq);
8590 :
8591 : /*
8592 : * We do not migrate tasks that are:
8593 : * 1) throttled_lb_pair, or
8594 : * 2) cannot be migrated to this CPU due to cpus_ptr, or
8595 : * 3) running (obviously), or
8596 : * 4) are cache-hot on their current CPU.
8597 : */
8598 : if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
8599 : return 0;
8600 :
8601 : /* Disregard pcpu kthreads; they are where they need to be. */
8602 : if (kthread_is_per_cpu(p))
8603 : return 0;
8604 :
8605 : if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
8606 : int cpu;
8607 :
8608 : schedstat_inc(p->stats.nr_failed_migrations_affine);
8609 :
8610 : env->flags |= LBF_SOME_PINNED;
8611 :
8612 : /*
8613 : * Remember if this task can be migrated to any other CPU in
8614 : * our sched_group. We may want to revisit it if we couldn't
8615 : * meet load balance goals by pulling other tasks on src_cpu.
8616 : *
8617 : * Avoid computing new_dst_cpu
8618 : * - for NEWLY_IDLE
8619 : * - if we have already computed one in current iteration
8620 : * - if it's an active balance
8621 : */
8622 : if (env->idle == CPU_NEWLY_IDLE ||
8623 : env->flags & (LBF_DST_PINNED | LBF_ACTIVE_LB))
8624 : return 0;
8625 :
8626 : /* Prevent to re-select dst_cpu via env's CPUs: */
8627 : for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
8628 : if (cpumask_test_cpu(cpu, p->cpus_ptr)) {
8629 : env->flags |= LBF_DST_PINNED;
8630 : env->new_dst_cpu = cpu;
8631 : break;
8632 : }
8633 : }
8634 :
8635 : return 0;
8636 : }
8637 :
8638 : /* Record that we found at least one task that could run on dst_cpu */
8639 : env->flags &= ~LBF_ALL_PINNED;
8640 :
8641 : if (task_on_cpu(env->src_rq, p)) {
8642 : schedstat_inc(p->stats.nr_failed_migrations_running);
8643 : return 0;
8644 : }
8645 :
8646 : /*
8647 : * Aggressive migration if:
8648 : * 1) active balance
8649 : * 2) destination numa is preferred
8650 : * 3) task is cache cold, or
8651 : * 4) too many balance attempts have failed.
8652 : */
8653 : if (env->flags & LBF_ACTIVE_LB)
8654 : return 1;
8655 :
8656 : tsk_cache_hot = migrate_degrades_locality(p, env);
8657 : if (tsk_cache_hot == -1)
8658 : tsk_cache_hot = task_hot(p, env);
8659 :
8660 : if (tsk_cache_hot <= 0 ||
8661 : env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
8662 : if (tsk_cache_hot == 1) {
8663 : schedstat_inc(env->sd->lb_hot_gained[env->idle]);
8664 : schedstat_inc(p->stats.nr_forced_migrations);
8665 : }
8666 : return 1;
8667 : }
8668 :
8669 : schedstat_inc(p->stats.nr_failed_migrations_hot);
8670 : return 0;
8671 : }
8672 :
8673 : /*
8674 : * detach_task() -- detach the task for the migration specified in env
8675 : */
8676 : static void detach_task(struct task_struct *p, struct lb_env *env)
8677 : {
8678 : lockdep_assert_rq_held(env->src_rq);
8679 :
8680 : deactivate_task(env->src_rq, p, DEQUEUE_NOCLOCK);
8681 : set_task_cpu(p, env->dst_cpu);
8682 : }
8683 :
8684 : /*
8685 : * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
8686 : * part of active balancing operations within "domain".
8687 : *
8688 : * Returns a task if successful and NULL otherwise.
8689 : */
8690 : static struct task_struct *detach_one_task(struct lb_env *env)
8691 : {
8692 : struct task_struct *p;
8693 :
8694 : lockdep_assert_rq_held(env->src_rq);
8695 :
8696 : list_for_each_entry_reverse(p,
8697 : &env->src_rq->cfs_tasks, se.group_node) {
8698 : if (!can_migrate_task(p, env))
8699 : continue;
8700 :
8701 : detach_task(p, env);
8702 :
8703 : /*
8704 : * Right now, this is only the second place where
8705 : * lb_gained[env->idle] is updated (other is detach_tasks)
8706 : * so we can safely collect stats here rather than
8707 : * inside detach_tasks().
8708 : */
8709 : schedstat_inc(env->sd->lb_gained[env->idle]);
8710 : return p;
8711 : }
8712 : return NULL;
8713 : }
8714 :
8715 : /*
8716 : * detach_tasks() -- tries to detach up to imbalance load/util/tasks from
8717 : * busiest_rq, as part of a balancing operation within domain "sd".
8718 : *
8719 : * Returns number of detached tasks if successful and 0 otherwise.
8720 : */
8721 : static int detach_tasks(struct lb_env *env)
8722 : {
8723 : struct list_head *tasks = &env->src_rq->cfs_tasks;
8724 : unsigned long util, load;
8725 : struct task_struct *p;
8726 : int detached = 0;
8727 :
8728 : lockdep_assert_rq_held(env->src_rq);
8729 :
8730 : /*
8731 : * Source run queue has been emptied by another CPU, clear
8732 : * LBF_ALL_PINNED flag as we will not test any task.
8733 : */
8734 : if (env->src_rq->nr_running <= 1) {
8735 : env->flags &= ~LBF_ALL_PINNED;
8736 : return 0;
8737 : }
8738 :
8739 : if (env->imbalance <= 0)
8740 : return 0;
8741 :
8742 : while (!list_empty(tasks)) {
8743 : /*
8744 : * We don't want to steal all, otherwise we may be treated likewise,
8745 : * which could at worst lead to a livelock crash.
8746 : */
8747 : if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1)
8748 : break;
8749 :
8750 : env->loop++;
8751 : /*
8752 : * We've more or less seen every task there is, call it quits
8753 : * unless we haven't found any movable task yet.
8754 : */
8755 : if (env->loop > env->loop_max &&
8756 : !(env->flags & LBF_ALL_PINNED))
8757 : break;
8758 :
8759 : /* take a breather every nr_migrate tasks */
8760 : if (env->loop > env->loop_break) {
8761 : env->loop_break += SCHED_NR_MIGRATE_BREAK;
8762 : env->flags |= LBF_NEED_BREAK;
8763 : break;
8764 : }
8765 :
8766 : p = list_last_entry(tasks, struct task_struct, se.group_node);
8767 :
8768 : if (!can_migrate_task(p, env))
8769 : goto next;
8770 :
8771 : switch (env->migration_type) {
8772 : case migrate_load:
8773 : /*
8774 : * Depending of the number of CPUs and tasks and the
8775 : * cgroup hierarchy, task_h_load() can return a null
8776 : * value. Make sure that env->imbalance decreases
8777 : * otherwise detach_tasks() will stop only after
8778 : * detaching up to loop_max tasks.
8779 : */
8780 : load = max_t(unsigned long, task_h_load(p), 1);
8781 :
8782 : if (sched_feat(LB_MIN) &&
8783 : load < 16 && !env->sd->nr_balance_failed)
8784 : goto next;
8785 :
8786 : /*
8787 : * Make sure that we don't migrate too much load.
8788 : * Nevertheless, let relax the constraint if
8789 : * scheduler fails to find a good waiting task to
8790 : * migrate.
8791 : */
8792 : if (shr_bound(load, env->sd->nr_balance_failed) > env->imbalance)
8793 : goto next;
8794 :
8795 : env->imbalance -= load;
8796 : break;
8797 :
8798 : case migrate_util:
8799 : util = task_util_est(p);
8800 :
8801 : if (util > env->imbalance)
8802 : goto next;
8803 :
8804 : env->imbalance -= util;
8805 : break;
8806 :
8807 : case migrate_task:
8808 : env->imbalance--;
8809 : break;
8810 :
8811 : case migrate_misfit:
8812 : /* This is not a misfit task */
8813 : if (task_fits_cpu(p, env->src_cpu))
8814 : goto next;
8815 :
8816 : env->imbalance = 0;
8817 : break;
8818 : }
8819 :
8820 : detach_task(p, env);
8821 : list_add(&p->se.group_node, &env->tasks);
8822 :
8823 : detached++;
8824 :
8825 : #ifdef CONFIG_PREEMPTION
8826 : /*
8827 : * NEWIDLE balancing is a source of latency, so preemptible
8828 : * kernels will stop after the first task is detached to minimize
8829 : * the critical section.
8830 : */
8831 : if (env->idle == CPU_NEWLY_IDLE)
8832 : break;
8833 : #endif
8834 :
8835 : /*
8836 : * We only want to steal up to the prescribed amount of
8837 : * load/util/tasks.
8838 : */
8839 : if (env->imbalance <= 0)
8840 : break;
8841 :
8842 : continue;
8843 : next:
8844 : list_move(&p->se.group_node, tasks);
8845 : }
8846 :
8847 : /*
8848 : * Right now, this is one of only two places we collect this stat
8849 : * so we can safely collect detach_one_task() stats here rather
8850 : * than inside detach_one_task().
8851 : */
8852 : schedstat_add(env->sd->lb_gained[env->idle], detached);
8853 :
8854 : return detached;
8855 : }
8856 :
8857 : /*
8858 : * attach_task() -- attach the task detached by detach_task() to its new rq.
8859 : */
8860 : static void attach_task(struct rq *rq, struct task_struct *p)
8861 : {
8862 : lockdep_assert_rq_held(rq);
8863 :
8864 : WARN_ON_ONCE(task_rq(p) != rq);
8865 : activate_task(rq, p, ENQUEUE_NOCLOCK);
8866 : check_preempt_curr(rq, p, 0);
8867 : }
8868 :
8869 : /*
8870 : * attach_one_task() -- attaches the task returned from detach_one_task() to
8871 : * its new rq.
8872 : */
8873 : static void attach_one_task(struct rq *rq, struct task_struct *p)
8874 : {
8875 : struct rq_flags rf;
8876 :
8877 : rq_lock(rq, &rf);
8878 : update_rq_clock(rq);
8879 : attach_task(rq, p);
8880 : rq_unlock(rq, &rf);
8881 : }
8882 :
8883 : /*
8884 : * attach_tasks() -- attaches all tasks detached by detach_tasks() to their
8885 : * new rq.
8886 : */
8887 : static void attach_tasks(struct lb_env *env)
8888 : {
8889 : struct list_head *tasks = &env->tasks;
8890 : struct task_struct *p;
8891 : struct rq_flags rf;
8892 :
8893 : rq_lock(env->dst_rq, &rf);
8894 : update_rq_clock(env->dst_rq);
8895 :
8896 : while (!list_empty(tasks)) {
8897 : p = list_first_entry(tasks, struct task_struct, se.group_node);
8898 : list_del_init(&p->se.group_node);
8899 :
8900 : attach_task(env->dst_rq, p);
8901 : }
8902 :
8903 : rq_unlock(env->dst_rq, &rf);
8904 : }
8905 :
8906 : #ifdef CONFIG_NO_HZ_COMMON
8907 : static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
8908 : {
8909 : if (cfs_rq->avg.load_avg)
8910 : return true;
8911 :
8912 : if (cfs_rq->avg.util_avg)
8913 : return true;
8914 :
8915 : return false;
8916 : }
8917 :
8918 : static inline bool others_have_blocked(struct rq *rq)
8919 : {
8920 : if (READ_ONCE(rq->avg_rt.util_avg))
8921 : return true;
8922 :
8923 : if (READ_ONCE(rq->avg_dl.util_avg))
8924 : return true;
8925 :
8926 : if (thermal_load_avg(rq))
8927 : return true;
8928 :
8929 : #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
8930 : if (READ_ONCE(rq->avg_irq.util_avg))
8931 : return true;
8932 : #endif
8933 :
8934 : return false;
8935 : }
8936 :
8937 : static inline void update_blocked_load_tick(struct rq *rq)
8938 : {
8939 : WRITE_ONCE(rq->last_blocked_load_update_tick, jiffies);
8940 : }
8941 :
8942 : static inline void update_blocked_load_status(struct rq *rq, bool has_blocked)
8943 : {
8944 : if (!has_blocked)
8945 : rq->has_blocked_load = 0;
8946 : }
8947 : #else
8948 : static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) { return false; }
8949 : static inline bool others_have_blocked(struct rq *rq) { return false; }
8950 : static inline void update_blocked_load_tick(struct rq *rq) {}
8951 : static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {}
8952 : #endif
8953 :
8954 : static bool __update_blocked_others(struct rq *rq, bool *done)
8955 : {
8956 : const struct sched_class *curr_class;
8957 : u64 now = rq_clock_pelt(rq);
8958 : unsigned long thermal_pressure;
8959 : bool decayed;
8960 :
8961 : /*
8962 : * update_load_avg() can call cpufreq_update_util(). Make sure that RT,
8963 : * DL and IRQ signals have been updated before updating CFS.
8964 : */
8965 : curr_class = rq->curr->sched_class;
8966 :
8967 : thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
8968 :
8969 : decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
8970 : update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
8971 : update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
8972 : update_irq_load_avg(rq, 0);
8973 :
8974 : if (others_have_blocked(rq))
8975 : *done = false;
8976 :
8977 : return decayed;
8978 : }
8979 :
8980 : #ifdef CONFIG_FAIR_GROUP_SCHED
8981 :
8982 : static bool __update_blocked_fair(struct rq *rq, bool *done)
8983 : {
8984 : struct cfs_rq *cfs_rq, *pos;
8985 : bool decayed = false;
8986 : int cpu = cpu_of(rq);
8987 :
8988 : /*
8989 : * Iterates the task_group tree in a bottom up fashion, see
8990 : * list_add_leaf_cfs_rq() for details.
8991 : */
8992 : for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) {
8993 : struct sched_entity *se;
8994 :
8995 : if (update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq)) {
8996 : update_tg_load_avg(cfs_rq);
8997 :
8998 : if (cfs_rq->nr_running == 0)
8999 : update_idle_cfs_rq_clock_pelt(cfs_rq);
9000 :
9001 : if (cfs_rq == &rq->cfs)
9002 : decayed = true;
9003 : }
9004 :
9005 : /* Propagate pending load changes to the parent, if any: */
9006 : se = cfs_rq->tg->se[cpu];
9007 : if (se && !skip_blocked_update(se))
9008 : update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
9009 :
9010 : /*
9011 : * There can be a lot of idle CPU cgroups. Don't let fully
9012 : * decayed cfs_rqs linger on the list.
9013 : */
9014 : if (cfs_rq_is_decayed(cfs_rq))
9015 : list_del_leaf_cfs_rq(cfs_rq);
9016 :
9017 : /* Don't need periodic decay once load/util_avg are null */
9018 : if (cfs_rq_has_blocked(cfs_rq))
9019 : *done = false;
9020 : }
9021 :
9022 : return decayed;
9023 : }
9024 :
9025 : /*
9026 : * Compute the hierarchical load factor for cfs_rq and all its ascendants.
9027 : * This needs to be done in a top-down fashion because the load of a child
9028 : * group is a fraction of its parents load.
9029 : */
9030 : static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
9031 : {
9032 : struct rq *rq = rq_of(cfs_rq);
9033 : struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
9034 : unsigned long now = jiffies;
9035 : unsigned long load;
9036 :
9037 : if (cfs_rq->last_h_load_update == now)
9038 : return;
9039 :
9040 : WRITE_ONCE(cfs_rq->h_load_next, NULL);
9041 : for_each_sched_entity(se) {
9042 : cfs_rq = cfs_rq_of(se);
9043 : WRITE_ONCE(cfs_rq->h_load_next, se);
9044 : if (cfs_rq->last_h_load_update == now)
9045 : break;
9046 : }
9047 :
9048 : if (!se) {
9049 : cfs_rq->h_load = cfs_rq_load_avg(cfs_rq);
9050 : cfs_rq->last_h_load_update = now;
9051 : }
9052 :
9053 : while ((se = READ_ONCE(cfs_rq->h_load_next)) != NULL) {
9054 : load = cfs_rq->h_load;
9055 : load = div64_ul(load * se->avg.load_avg,
9056 : cfs_rq_load_avg(cfs_rq) + 1);
9057 : cfs_rq = group_cfs_rq(se);
9058 : cfs_rq->h_load = load;
9059 : cfs_rq->last_h_load_update = now;
9060 : }
9061 : }
9062 :
9063 : static unsigned long task_h_load(struct task_struct *p)
9064 : {
9065 : struct cfs_rq *cfs_rq = task_cfs_rq(p);
9066 :
9067 : update_cfs_rq_h_load(cfs_rq);
9068 : return div64_ul(p->se.avg.load_avg * cfs_rq->h_load,
9069 : cfs_rq_load_avg(cfs_rq) + 1);
9070 : }
9071 : #else
9072 : static bool __update_blocked_fair(struct rq *rq, bool *done)
9073 : {
9074 : struct cfs_rq *cfs_rq = &rq->cfs;
9075 : bool decayed;
9076 :
9077 : decayed = update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
9078 : if (cfs_rq_has_blocked(cfs_rq))
9079 : *done = false;
9080 :
9081 : return decayed;
9082 : }
9083 :
9084 : static unsigned long task_h_load(struct task_struct *p)
9085 : {
9086 : return p->se.avg.load_avg;
9087 : }
9088 : #endif
9089 :
9090 : static void update_blocked_averages(int cpu)
9091 : {
9092 : bool decayed = false, done = true;
9093 : struct rq *rq = cpu_rq(cpu);
9094 : struct rq_flags rf;
9095 :
9096 : rq_lock_irqsave(rq, &rf);
9097 : update_blocked_load_tick(rq);
9098 : update_rq_clock(rq);
9099 :
9100 : decayed |= __update_blocked_others(rq, &done);
9101 : decayed |= __update_blocked_fair(rq, &done);
9102 :
9103 : update_blocked_load_status(rq, !done);
9104 : if (decayed)
9105 : cpufreq_update_util(rq, 0);
9106 : rq_unlock_irqrestore(rq, &rf);
9107 : }
9108 :
9109 : /********** Helpers for find_busiest_group ************************/
9110 :
9111 : /*
9112 : * sg_lb_stats - stats of a sched_group required for load_balancing
9113 : */
9114 : struct sg_lb_stats {
9115 : unsigned long avg_load; /*Avg load across the CPUs of the group */
9116 : unsigned long group_load; /* Total load over the CPUs of the group */
9117 : unsigned long group_capacity;
9118 : unsigned long group_util; /* Total utilization over the CPUs of the group */
9119 : unsigned long group_runnable; /* Total runnable time over the CPUs of the group */
9120 : unsigned int sum_nr_running; /* Nr of tasks running in the group */
9121 : unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */
9122 : unsigned int idle_cpus;
9123 : unsigned int group_weight;
9124 : enum group_type group_type;
9125 : unsigned int group_asym_packing; /* Tasks should be moved to preferred CPU */
9126 : unsigned long group_misfit_task_load; /* A CPU has a task too big for its capacity */
9127 : #ifdef CONFIG_NUMA_BALANCING
9128 : unsigned int nr_numa_running;
9129 : unsigned int nr_preferred_running;
9130 : #endif
9131 : };
9132 :
9133 : /*
9134 : * sd_lb_stats - Structure to store the statistics of a sched_domain
9135 : * during load balancing.
9136 : */
9137 : struct sd_lb_stats {
9138 : struct sched_group *busiest; /* Busiest group in this sd */
9139 : struct sched_group *local; /* Local group in this sd */
9140 : unsigned long total_load; /* Total load of all groups in sd */
9141 : unsigned long total_capacity; /* Total capacity of all groups in sd */
9142 : unsigned long avg_load; /* Average load across all groups in sd */
9143 : unsigned int prefer_sibling; /* tasks should go to sibling first */
9144 :
9145 : struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */
9146 : struct sg_lb_stats local_stat; /* Statistics of the local group */
9147 : };
9148 :
9149 : static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
9150 : {
9151 : /*
9152 : * Skimp on the clearing to avoid duplicate work. We can avoid clearing
9153 : * local_stat because update_sg_lb_stats() does a full clear/assignment.
9154 : * We must however set busiest_stat::group_type and
9155 : * busiest_stat::idle_cpus to the worst busiest group because
9156 : * update_sd_pick_busiest() reads these before assignment.
9157 : */
9158 : *sds = (struct sd_lb_stats){
9159 : .busiest = NULL,
9160 : .local = NULL,
9161 : .total_load = 0UL,
9162 : .total_capacity = 0UL,
9163 : .busiest_stat = {
9164 : .idle_cpus = UINT_MAX,
9165 : .group_type = group_has_spare,
9166 : },
9167 : };
9168 : }
9169 :
9170 : static unsigned long scale_rt_capacity(int cpu)
9171 : {
9172 : struct rq *rq = cpu_rq(cpu);
9173 : unsigned long max = arch_scale_cpu_capacity(cpu);
9174 : unsigned long used, free;
9175 : unsigned long irq;
9176 :
9177 : irq = cpu_util_irq(rq);
9178 :
9179 : if (unlikely(irq >= max))
9180 : return 1;
9181 :
9182 : /*
9183 : * avg_rt.util_avg and avg_dl.util_avg track binary signals
9184 : * (running and not running) with weights 0 and 1024 respectively.
9185 : * avg_thermal.load_avg tracks thermal pressure and the weighted
9186 : * average uses the actual delta max capacity(load).
9187 : */
9188 : used = READ_ONCE(rq->avg_rt.util_avg);
9189 : used += READ_ONCE(rq->avg_dl.util_avg);
9190 : used += thermal_load_avg(rq);
9191 :
9192 : if (unlikely(used >= max))
9193 : return 1;
9194 :
9195 : free = max - used;
9196 :
9197 : return scale_irq_capacity(free, irq, max);
9198 : }
9199 :
9200 : static void update_cpu_capacity(struct sched_domain *sd, int cpu)
9201 : {
9202 : unsigned long capacity = scale_rt_capacity(cpu);
9203 : struct sched_group *sdg = sd->groups;
9204 :
9205 : cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu);
9206 :
9207 : if (!capacity)
9208 : capacity = 1;
9209 :
9210 : cpu_rq(cpu)->cpu_capacity = capacity;
9211 : trace_sched_cpu_capacity_tp(cpu_rq(cpu));
9212 :
9213 : sdg->sgc->capacity = capacity;
9214 : sdg->sgc->min_capacity = capacity;
9215 : sdg->sgc->max_capacity = capacity;
9216 : }
9217 :
9218 : void update_group_capacity(struct sched_domain *sd, int cpu)
9219 : {
9220 : struct sched_domain *child = sd->child;
9221 : struct sched_group *group, *sdg = sd->groups;
9222 : unsigned long capacity, min_capacity, max_capacity;
9223 : unsigned long interval;
9224 :
9225 : interval = msecs_to_jiffies(sd->balance_interval);
9226 : interval = clamp(interval, 1UL, max_load_balance_interval);
9227 : sdg->sgc->next_update = jiffies + interval;
9228 :
9229 : if (!child) {
9230 : update_cpu_capacity(sd, cpu);
9231 : return;
9232 : }
9233 :
9234 : capacity = 0;
9235 : min_capacity = ULONG_MAX;
9236 : max_capacity = 0;
9237 :
9238 : if (child->flags & SD_OVERLAP) {
9239 : /*
9240 : * SD_OVERLAP domains cannot assume that child groups
9241 : * span the current group.
9242 : */
9243 :
9244 : for_each_cpu(cpu, sched_group_span(sdg)) {
9245 : unsigned long cpu_cap = capacity_of(cpu);
9246 :
9247 : capacity += cpu_cap;
9248 : min_capacity = min(cpu_cap, min_capacity);
9249 : max_capacity = max(cpu_cap, max_capacity);
9250 : }
9251 : } else {
9252 : /*
9253 : * !SD_OVERLAP domains can assume that child groups
9254 : * span the current group.
9255 : */
9256 :
9257 : group = child->groups;
9258 : do {
9259 : struct sched_group_capacity *sgc = group->sgc;
9260 :
9261 : capacity += sgc->capacity;
9262 : min_capacity = min(sgc->min_capacity, min_capacity);
9263 : max_capacity = max(sgc->max_capacity, max_capacity);
9264 : group = group->next;
9265 : } while (group != child->groups);
9266 : }
9267 :
9268 : sdg->sgc->capacity = capacity;
9269 : sdg->sgc->min_capacity = min_capacity;
9270 : sdg->sgc->max_capacity = max_capacity;
9271 : }
9272 :
9273 : /*
9274 : * Check whether the capacity of the rq has been noticeably reduced by side
9275 : * activity. The imbalance_pct is used for the threshold.
9276 : * Return true is the capacity is reduced
9277 : */
9278 : static inline int
9279 : check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
9280 : {
9281 : return ((rq->cpu_capacity * sd->imbalance_pct) <
9282 : (rq->cpu_capacity_orig * 100));
9283 : }
9284 :
9285 : /*
9286 : * Check whether a rq has a misfit task and if it looks like we can actually
9287 : * help that task: we can migrate the task to a CPU of higher capacity, or
9288 : * the task's current CPU is heavily pressured.
9289 : */
9290 : static inline int check_misfit_status(struct rq *rq, struct sched_domain *sd)
9291 : {
9292 : return rq->misfit_task_load &&
9293 : (rq->cpu_capacity_orig < rq->rd->max_cpu_capacity ||
9294 : check_cpu_capacity(rq, sd));
9295 : }
9296 :
9297 : /*
9298 : * Group imbalance indicates (and tries to solve) the problem where balancing
9299 : * groups is inadequate due to ->cpus_ptr constraints.
9300 : *
9301 : * Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
9302 : * cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
9303 : * Something like:
9304 : *
9305 : * { 0 1 2 3 } { 4 5 6 7 }
9306 : * * * * *
9307 : *
9308 : * If we were to balance group-wise we'd place two tasks in the first group and
9309 : * two tasks in the second group. Clearly this is undesired as it will overload
9310 : * cpu 3 and leave one of the CPUs in the second group unused.
9311 : *
9312 : * The current solution to this issue is detecting the skew in the first group
9313 : * by noticing the lower domain failed to reach balance and had difficulty
9314 : * moving tasks due to affinity constraints.
9315 : *
9316 : * When this is so detected; this group becomes a candidate for busiest; see
9317 : * update_sd_pick_busiest(). And calculate_imbalance() and
9318 : * find_busiest_group() avoid some of the usual balance conditions to allow it
9319 : * to create an effective group imbalance.
9320 : *
9321 : * This is a somewhat tricky proposition since the next run might not find the
9322 : * group imbalance and decide the groups need to be balanced again. A most
9323 : * subtle and fragile situation.
9324 : */
9325 :
9326 : static inline int sg_imbalanced(struct sched_group *group)
9327 : {
9328 : return group->sgc->imbalance;
9329 : }
9330 :
9331 : /*
9332 : * group_has_capacity returns true if the group has spare capacity that could
9333 : * be used by some tasks.
9334 : * We consider that a group has spare capacity if the number of task is
9335 : * smaller than the number of CPUs or if the utilization is lower than the
9336 : * available capacity for CFS tasks.
9337 : * For the latter, we use a threshold to stabilize the state, to take into
9338 : * account the variance of the tasks' load and to return true if the available
9339 : * capacity in meaningful for the load balancer.
9340 : * As an example, an available capacity of 1% can appear but it doesn't make
9341 : * any benefit for the load balance.
9342 : */
9343 : static inline bool
9344 : group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
9345 : {
9346 : if (sgs->sum_nr_running < sgs->group_weight)
9347 : return true;
9348 :
9349 : if ((sgs->group_capacity * imbalance_pct) <
9350 : (sgs->group_runnable * 100))
9351 : return false;
9352 :
9353 : if ((sgs->group_capacity * 100) >
9354 : (sgs->group_util * imbalance_pct))
9355 : return true;
9356 :
9357 : return false;
9358 : }
9359 :
9360 : /*
9361 : * group_is_overloaded returns true if the group has more tasks than it can
9362 : * handle.
9363 : * group_is_overloaded is not equals to !group_has_capacity because a group
9364 : * with the exact right number of tasks, has no more spare capacity but is not
9365 : * overloaded so both group_has_capacity and group_is_overloaded return
9366 : * false.
9367 : */
9368 : static inline bool
9369 : group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
9370 : {
9371 : if (sgs->sum_nr_running <= sgs->group_weight)
9372 : return false;
9373 :
9374 : if ((sgs->group_capacity * 100) <
9375 : (sgs->group_util * imbalance_pct))
9376 : return true;
9377 :
9378 : if ((sgs->group_capacity * imbalance_pct) <
9379 : (sgs->group_runnable * 100))
9380 : return true;
9381 :
9382 : return false;
9383 : }
9384 :
9385 : static inline enum
9386 : group_type group_classify(unsigned int imbalance_pct,
9387 : struct sched_group *group,
9388 : struct sg_lb_stats *sgs)
9389 : {
9390 : if (group_is_overloaded(imbalance_pct, sgs))
9391 : return group_overloaded;
9392 :
9393 : if (sg_imbalanced(group))
9394 : return group_imbalanced;
9395 :
9396 : if (sgs->group_asym_packing)
9397 : return group_asym_packing;
9398 :
9399 : if (sgs->group_misfit_task_load)
9400 : return group_misfit_task;
9401 :
9402 : if (!group_has_capacity(imbalance_pct, sgs))
9403 : return group_fully_busy;
9404 :
9405 : return group_has_spare;
9406 : }
9407 :
9408 : /**
9409 : * sched_use_asym_prio - Check whether asym_packing priority must be used
9410 : * @sd: The scheduling domain of the load balancing
9411 : * @cpu: A CPU
9412 : *
9413 : * Always use CPU priority when balancing load between SMT siblings. When
9414 : * balancing load between cores, it is not sufficient that @cpu is idle. Only
9415 : * use CPU priority if the whole core is idle.
9416 : *
9417 : * Returns: True if the priority of @cpu must be followed. False otherwise.
9418 : */
9419 : static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
9420 : {
9421 : if (!sched_smt_active())
9422 : return true;
9423 :
9424 : return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
9425 : }
9426 :
9427 : /**
9428 : * sched_asym - Check if the destination CPU can do asym_packing load balance
9429 : * @env: The load balancing environment
9430 : * @sds: Load-balancing data with statistics of the local group
9431 : * @sgs: Load-balancing statistics of the candidate busiest group
9432 : * @group: The candidate busiest group
9433 : *
9434 : * @env::dst_cpu can do asym_packing if it has higher priority than the
9435 : * preferred CPU of @group.
9436 : *
9437 : * SMT is a special case. If we are balancing load between cores, @env::dst_cpu
9438 : * can do asym_packing balance only if all its SMT siblings are idle. Also, it
9439 : * can only do it if @group is an SMT group and has exactly on busy CPU. Larger
9440 : * imbalances in the number of CPUS are dealt with in find_busiest_group().
9441 : *
9442 : * If we are balancing load within an SMT core, or at DIE domain level, always
9443 : * proceed.
9444 : *
9445 : * Return: true if @env::dst_cpu can do with asym_packing load balance. False
9446 : * otherwise.
9447 : */
9448 : static inline bool
9449 : sched_asym(struct lb_env *env, struct sd_lb_stats *sds, struct sg_lb_stats *sgs,
9450 : struct sched_group *group)
9451 : {
9452 : /* Ensure that the whole local core is idle, if applicable. */
9453 : if (!sched_use_asym_prio(env->sd, env->dst_cpu))
9454 : return false;
9455 :
9456 : /*
9457 : * CPU priorities does not make sense for SMT cores with more than one
9458 : * busy sibling.
9459 : */
9460 : if (group->flags & SD_SHARE_CPUCAPACITY) {
9461 : if (sgs->group_weight - sgs->idle_cpus != 1)
9462 : return false;
9463 : }
9464 :
9465 : return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu);
9466 : }
9467 :
9468 : static inline bool
9469 : sched_reduced_capacity(struct rq *rq, struct sched_domain *sd)
9470 : {
9471 : /*
9472 : * When there is more than 1 task, the group_overloaded case already
9473 : * takes care of cpu with reduced capacity
9474 : */
9475 : if (rq->cfs.h_nr_running != 1)
9476 : return false;
9477 :
9478 : return check_cpu_capacity(rq, sd);
9479 : }
9480 :
9481 : /**
9482 : * update_sg_lb_stats - Update sched_group's statistics for load balancing.
9483 : * @env: The load balancing environment.
9484 : * @sds: Load-balancing data with statistics of the local group.
9485 : * @group: sched_group whose statistics are to be updated.
9486 : * @sgs: variable to hold the statistics for this group.
9487 : * @sg_status: Holds flag indicating the status of the sched_group
9488 : */
9489 : static inline void update_sg_lb_stats(struct lb_env *env,
9490 : struct sd_lb_stats *sds,
9491 : struct sched_group *group,
9492 : struct sg_lb_stats *sgs,
9493 : int *sg_status)
9494 : {
9495 : int i, nr_running, local_group;
9496 :
9497 : memset(sgs, 0, sizeof(*sgs));
9498 :
9499 : local_group = group == sds->local;
9500 :
9501 : for_each_cpu_and(i, sched_group_span(group), env->cpus) {
9502 : struct rq *rq = cpu_rq(i);
9503 : unsigned long load = cpu_load(rq);
9504 :
9505 : sgs->group_load += load;
9506 : sgs->group_util += cpu_util_cfs(i);
9507 : sgs->group_runnable += cpu_runnable(rq);
9508 : sgs->sum_h_nr_running += rq->cfs.h_nr_running;
9509 :
9510 : nr_running = rq->nr_running;
9511 : sgs->sum_nr_running += nr_running;
9512 :
9513 : if (nr_running > 1)
9514 : *sg_status |= SG_OVERLOAD;
9515 :
9516 : if (cpu_overutilized(i))
9517 : *sg_status |= SG_OVERUTILIZED;
9518 :
9519 : #ifdef CONFIG_NUMA_BALANCING
9520 : sgs->nr_numa_running += rq->nr_numa_running;
9521 : sgs->nr_preferred_running += rq->nr_preferred_running;
9522 : #endif
9523 : /*
9524 : * No need to call idle_cpu() if nr_running is not 0
9525 : */
9526 : if (!nr_running && idle_cpu(i)) {
9527 : sgs->idle_cpus++;
9528 : /* Idle cpu can't have misfit task */
9529 : continue;
9530 : }
9531 :
9532 : if (local_group)
9533 : continue;
9534 :
9535 : if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
9536 : /* Check for a misfit task on the cpu */
9537 : if (sgs->group_misfit_task_load < rq->misfit_task_load) {
9538 : sgs->group_misfit_task_load = rq->misfit_task_load;
9539 : *sg_status |= SG_OVERLOAD;
9540 : }
9541 : } else if ((env->idle != CPU_NOT_IDLE) &&
9542 : sched_reduced_capacity(rq, env->sd)) {
9543 : /* Check for a task running on a CPU with reduced capacity */
9544 : if (sgs->group_misfit_task_load < load)
9545 : sgs->group_misfit_task_load = load;
9546 : }
9547 : }
9548 :
9549 : sgs->group_capacity = group->sgc->capacity;
9550 :
9551 : sgs->group_weight = group->group_weight;
9552 :
9553 : /* Check if dst CPU is idle and preferred to this group */
9554 : if (!local_group && env->sd->flags & SD_ASYM_PACKING &&
9555 : env->idle != CPU_NOT_IDLE && sgs->sum_h_nr_running &&
9556 : sched_asym(env, sds, sgs, group)) {
9557 : sgs->group_asym_packing = 1;
9558 : }
9559 :
9560 : sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);
9561 :
9562 : /* Computing avg_load makes sense only when group is overloaded */
9563 : if (sgs->group_type == group_overloaded)
9564 : sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
9565 : sgs->group_capacity;
9566 : }
9567 :
9568 : /**
9569 : * update_sd_pick_busiest - return 1 on busiest group
9570 : * @env: The load balancing environment.
9571 : * @sds: sched_domain statistics
9572 : * @sg: sched_group candidate to be checked for being the busiest
9573 : * @sgs: sched_group statistics
9574 : *
9575 : * Determine if @sg is a busier group than the previously selected
9576 : * busiest group.
9577 : *
9578 : * Return: %true if @sg is a busier group than the previously selected
9579 : * busiest group. %false otherwise.
9580 : */
9581 : static bool update_sd_pick_busiest(struct lb_env *env,
9582 : struct sd_lb_stats *sds,
9583 : struct sched_group *sg,
9584 : struct sg_lb_stats *sgs)
9585 : {
9586 : struct sg_lb_stats *busiest = &sds->busiest_stat;
9587 :
9588 : /* Make sure that there is at least one task to pull */
9589 : if (!sgs->sum_h_nr_running)
9590 : return false;
9591 :
9592 : /*
9593 : * Don't try to pull misfit tasks we can't help.
9594 : * We can use max_capacity here as reduction in capacity on some
9595 : * CPUs in the group should either be possible to resolve
9596 : * internally or be covered by avg_load imbalance (eventually).
9597 : */
9598 : if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
9599 : (sgs->group_type == group_misfit_task) &&
9600 : (!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) ||
9601 : sds->local_stat.group_type != group_has_spare))
9602 : return false;
9603 :
9604 : if (sgs->group_type > busiest->group_type)
9605 : return true;
9606 :
9607 : if (sgs->group_type < busiest->group_type)
9608 : return false;
9609 :
9610 : /*
9611 : * The candidate and the current busiest group are the same type of
9612 : * group. Let check which one is the busiest according to the type.
9613 : */
9614 :
9615 : switch (sgs->group_type) {
9616 : case group_overloaded:
9617 : /* Select the overloaded group with highest avg_load. */
9618 : if (sgs->avg_load <= busiest->avg_load)
9619 : return false;
9620 : break;
9621 :
9622 : case group_imbalanced:
9623 : /*
9624 : * Select the 1st imbalanced group as we don't have any way to
9625 : * choose one more than another.
9626 : */
9627 : return false;
9628 :
9629 : case group_asym_packing:
9630 : /* Prefer to move from lowest priority CPU's work */
9631 : if (sched_asym_prefer(sg->asym_prefer_cpu, sds->busiest->asym_prefer_cpu))
9632 : return false;
9633 : break;
9634 :
9635 : case group_misfit_task:
9636 : /*
9637 : * If we have more than one misfit sg go with the biggest
9638 : * misfit.
9639 : */
9640 : if (sgs->group_misfit_task_load < busiest->group_misfit_task_load)
9641 : return false;
9642 : break;
9643 :
9644 : case group_fully_busy:
9645 : /*
9646 : * Select the fully busy group with highest avg_load. In
9647 : * theory, there is no need to pull task from such kind of
9648 : * group because tasks have all compute capacity that they need
9649 : * but we can still improve the overall throughput by reducing
9650 : * contention when accessing shared HW resources.
9651 : *
9652 : * XXX for now avg_load is not computed and always 0 so we
9653 : * select the 1st one, except if @sg is composed of SMT
9654 : * siblings.
9655 : */
9656 :
9657 : if (sgs->avg_load < busiest->avg_load)
9658 : return false;
9659 :
9660 : if (sgs->avg_load == busiest->avg_load) {
9661 : /*
9662 : * SMT sched groups need more help than non-SMT groups.
9663 : * If @sg happens to also be SMT, either choice is good.
9664 : */
9665 : if (sds->busiest->flags & SD_SHARE_CPUCAPACITY)
9666 : return false;
9667 : }
9668 :
9669 : break;
9670 :
9671 : case group_has_spare:
9672 : /*
9673 : * Select not overloaded group with lowest number of idle cpus
9674 : * and highest number of running tasks. We could also compare
9675 : * the spare capacity which is more stable but it can end up
9676 : * that the group has less spare capacity but finally more idle
9677 : * CPUs which means less opportunity to pull tasks.
9678 : */
9679 : if (sgs->idle_cpus > busiest->idle_cpus)
9680 : return false;
9681 : else if ((sgs->idle_cpus == busiest->idle_cpus) &&
9682 : (sgs->sum_nr_running <= busiest->sum_nr_running))
9683 : return false;
9684 :
9685 : break;
9686 : }
9687 :
9688 : /*
9689 : * Candidate sg has no more than one task per CPU and has higher
9690 : * per-CPU capacity. Migrating tasks to less capable CPUs may harm
9691 : * throughput. Maximize throughput, power/energy consequences are not
9692 : * considered.
9693 : */
9694 : if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
9695 : (sgs->group_type <= group_fully_busy) &&
9696 : (capacity_greater(sg->sgc->min_capacity, capacity_of(env->dst_cpu))))
9697 : return false;
9698 :
9699 : return true;
9700 : }
9701 :
9702 : #ifdef CONFIG_NUMA_BALANCING
9703 : static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
9704 : {
9705 : if (sgs->sum_h_nr_running > sgs->nr_numa_running)
9706 : return regular;
9707 : if (sgs->sum_h_nr_running > sgs->nr_preferred_running)
9708 : return remote;
9709 : return all;
9710 : }
9711 :
9712 : static inline enum fbq_type fbq_classify_rq(struct rq *rq)
9713 : {
9714 : if (rq->nr_running > rq->nr_numa_running)
9715 : return regular;
9716 : if (rq->nr_running > rq->nr_preferred_running)
9717 : return remote;
9718 : return all;
9719 : }
9720 : #else
9721 : static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
9722 : {
9723 : return all;
9724 : }
9725 :
9726 : static inline enum fbq_type fbq_classify_rq(struct rq *rq)
9727 : {
9728 : return regular;
9729 : }
9730 : #endif /* CONFIG_NUMA_BALANCING */
9731 :
9732 :
9733 : struct sg_lb_stats;
9734 :
9735 : /*
9736 : * task_running_on_cpu - return 1 if @p is running on @cpu.
9737 : */
9738 :
9739 : static unsigned int task_running_on_cpu(int cpu, struct task_struct *p)
9740 : {
9741 : /* Task has no contribution or is new */
9742 : if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
9743 : return 0;
9744 :
9745 : if (task_on_rq_queued(p))
9746 : return 1;
9747 :
9748 : return 0;
9749 : }
9750 :
9751 : /**
9752 : * idle_cpu_without - would a given CPU be idle without p ?
9753 : * @cpu: the processor on which idleness is tested.
9754 : * @p: task which should be ignored.
9755 : *
9756 : * Return: 1 if the CPU would be idle. 0 otherwise.
9757 : */
9758 : static int idle_cpu_without(int cpu, struct task_struct *p)
9759 : {
9760 : struct rq *rq = cpu_rq(cpu);
9761 :
9762 : if (rq->curr != rq->idle && rq->curr != p)
9763 : return 0;
9764 :
9765 : /*
9766 : * rq->nr_running can't be used but an updated version without the
9767 : * impact of p on cpu must be used instead. The updated nr_running
9768 : * be computed and tested before calling idle_cpu_without().
9769 : */
9770 :
9771 : #ifdef CONFIG_SMP
9772 : if (rq->ttwu_pending)
9773 : return 0;
9774 : #endif
9775 :
9776 : return 1;
9777 : }
9778 :
9779 : /*
9780 : * update_sg_wakeup_stats - Update sched_group's statistics for wakeup.
9781 : * @sd: The sched_domain level to look for idlest group.
9782 : * @group: sched_group whose statistics are to be updated.
9783 : * @sgs: variable to hold the statistics for this group.
9784 : * @p: The task for which we look for the idlest group/CPU.
9785 : */
9786 : static inline void update_sg_wakeup_stats(struct sched_domain *sd,
9787 : struct sched_group *group,
9788 : struct sg_lb_stats *sgs,
9789 : struct task_struct *p)
9790 : {
9791 : int i, nr_running;
9792 :
9793 : memset(sgs, 0, sizeof(*sgs));
9794 :
9795 : /* Assume that task can't fit any CPU of the group */
9796 : if (sd->flags & SD_ASYM_CPUCAPACITY)
9797 : sgs->group_misfit_task_load = 1;
9798 :
9799 : for_each_cpu(i, sched_group_span(group)) {
9800 : struct rq *rq = cpu_rq(i);
9801 : unsigned int local;
9802 :
9803 : sgs->group_load += cpu_load_without(rq, p);
9804 : sgs->group_util += cpu_util_without(i, p);
9805 : sgs->group_runnable += cpu_runnable_without(rq, p);
9806 : local = task_running_on_cpu(i, p);
9807 : sgs->sum_h_nr_running += rq->cfs.h_nr_running - local;
9808 :
9809 : nr_running = rq->nr_running - local;
9810 : sgs->sum_nr_running += nr_running;
9811 :
9812 : /*
9813 : * No need to call idle_cpu_without() if nr_running is not 0
9814 : */
9815 : if (!nr_running && idle_cpu_without(i, p))
9816 : sgs->idle_cpus++;
9817 :
9818 : /* Check if task fits in the CPU */
9819 : if (sd->flags & SD_ASYM_CPUCAPACITY &&
9820 : sgs->group_misfit_task_load &&
9821 : task_fits_cpu(p, i))
9822 : sgs->group_misfit_task_load = 0;
9823 :
9824 : }
9825 :
9826 : sgs->group_capacity = group->sgc->capacity;
9827 :
9828 : sgs->group_weight = group->group_weight;
9829 :
9830 : sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
9831 :
9832 : /*
9833 : * Computing avg_load makes sense only when group is fully busy or
9834 : * overloaded
9835 : */
9836 : if (sgs->group_type == group_fully_busy ||
9837 : sgs->group_type == group_overloaded)
9838 : sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
9839 : sgs->group_capacity;
9840 : }
9841 :
9842 : static bool update_pick_idlest(struct sched_group *idlest,
9843 : struct sg_lb_stats *idlest_sgs,
9844 : struct sched_group *group,
9845 : struct sg_lb_stats *sgs)
9846 : {
9847 : if (sgs->group_type < idlest_sgs->group_type)
9848 : return true;
9849 :
9850 : if (sgs->group_type > idlest_sgs->group_type)
9851 : return false;
9852 :
9853 : /*
9854 : * The candidate and the current idlest group are the same type of
9855 : * group. Let check which one is the idlest according to the type.
9856 : */
9857 :
9858 : switch (sgs->group_type) {
9859 : case group_overloaded:
9860 : case group_fully_busy:
9861 : /* Select the group with lowest avg_load. */
9862 : if (idlest_sgs->avg_load <= sgs->avg_load)
9863 : return false;
9864 : break;
9865 :
9866 : case group_imbalanced:
9867 : case group_asym_packing:
9868 : /* Those types are not used in the slow wakeup path */
9869 : return false;
9870 :
9871 : case group_misfit_task:
9872 : /* Select group with the highest max capacity */
9873 : if (idlest->sgc->max_capacity >= group->sgc->max_capacity)
9874 : return false;
9875 : break;
9876 :
9877 : case group_has_spare:
9878 : /* Select group with most idle CPUs */
9879 : if (idlest_sgs->idle_cpus > sgs->idle_cpus)
9880 : return false;
9881 :
9882 : /* Select group with lowest group_util */
9883 : if (idlest_sgs->idle_cpus == sgs->idle_cpus &&
9884 : idlest_sgs->group_util <= sgs->group_util)
9885 : return false;
9886 :
9887 : break;
9888 : }
9889 :
9890 : return true;
9891 : }
9892 :
9893 : /*
9894 : * find_idlest_group() finds and returns the least busy CPU group within the
9895 : * domain.
9896 : *
9897 : * Assumes p is allowed on at least one CPU in sd.
9898 : */
9899 : static struct sched_group *
9900 : find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
9901 : {
9902 : struct sched_group *idlest = NULL, *local = NULL, *group = sd->groups;
9903 : struct sg_lb_stats local_sgs, tmp_sgs;
9904 : struct sg_lb_stats *sgs;
9905 : unsigned long imbalance;
9906 : struct sg_lb_stats idlest_sgs = {
9907 : .avg_load = UINT_MAX,
9908 : .group_type = group_overloaded,
9909 : };
9910 :
9911 : do {
9912 : int local_group;
9913 :
9914 : /* Skip over this group if it has no CPUs allowed */
9915 : if (!cpumask_intersects(sched_group_span(group),
9916 : p->cpus_ptr))
9917 : continue;
9918 :
9919 : /* Skip over this group if no cookie matched */
9920 : if (!sched_group_cookie_match(cpu_rq(this_cpu), p, group))
9921 : continue;
9922 :
9923 : local_group = cpumask_test_cpu(this_cpu,
9924 : sched_group_span(group));
9925 :
9926 : if (local_group) {
9927 : sgs = &local_sgs;
9928 : local = group;
9929 : } else {
9930 : sgs = &tmp_sgs;
9931 : }
9932 :
9933 : update_sg_wakeup_stats(sd, group, sgs, p);
9934 :
9935 : if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs)) {
9936 : idlest = group;
9937 : idlest_sgs = *sgs;
9938 : }
9939 :
9940 : } while (group = group->next, group != sd->groups);
9941 :
9942 :
9943 : /* There is no idlest group to push tasks to */
9944 : if (!idlest)
9945 : return NULL;
9946 :
9947 : /* The local group has been skipped because of CPU affinity */
9948 : if (!local)
9949 : return idlest;
9950 :
9951 : /*
9952 : * If the local group is idler than the selected idlest group
9953 : * don't try and push the task.
9954 : */
9955 : if (local_sgs.group_type < idlest_sgs.group_type)
9956 : return NULL;
9957 :
9958 : /*
9959 : * If the local group is busier than the selected idlest group
9960 : * try and push the task.
9961 : */
9962 : if (local_sgs.group_type > idlest_sgs.group_type)
9963 : return idlest;
9964 :
9965 : switch (local_sgs.group_type) {
9966 : case group_overloaded:
9967 : case group_fully_busy:
9968 :
9969 : /* Calculate allowed imbalance based on load */
9970 : imbalance = scale_load_down(NICE_0_LOAD) *
9971 : (sd->imbalance_pct-100) / 100;
9972 :
9973 : /*
9974 : * When comparing groups across NUMA domains, it's possible for
9975 : * the local domain to be very lightly loaded relative to the
9976 : * remote domains but "imbalance" skews the comparison making
9977 : * remote CPUs look much more favourable. When considering
9978 : * cross-domain, add imbalance to the load on the remote node
9979 : * and consider staying local.
9980 : */
9981 :
9982 : if ((sd->flags & SD_NUMA) &&
9983 : ((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
9984 : return NULL;
9985 :
9986 : /*
9987 : * If the local group is less loaded than the selected
9988 : * idlest group don't try and push any tasks.
9989 : */
9990 : if (idlest_sgs.avg_load >= (local_sgs.avg_load + imbalance))
9991 : return NULL;
9992 :
9993 : if (100 * local_sgs.avg_load <= sd->imbalance_pct * idlest_sgs.avg_load)
9994 : return NULL;
9995 : break;
9996 :
9997 : case group_imbalanced:
9998 : case group_asym_packing:
9999 : /* Those type are not used in the slow wakeup path */
10000 : return NULL;
10001 :
10002 : case group_misfit_task:
10003 : /* Select group with the highest max capacity */
10004 : if (local->sgc->max_capacity >= idlest->sgc->max_capacity)
10005 : return NULL;
10006 : break;
10007 :
10008 : case group_has_spare:
10009 : #ifdef CONFIG_NUMA
10010 : if (sd->flags & SD_NUMA) {
10011 : int imb_numa_nr = sd->imb_numa_nr;
10012 : #ifdef CONFIG_NUMA_BALANCING
10013 : int idlest_cpu;
10014 : /*
10015 : * If there is spare capacity at NUMA, try to select
10016 : * the preferred node
10017 : */
10018 : if (cpu_to_node(this_cpu) == p->numa_preferred_nid)
10019 : return NULL;
10020 :
10021 : idlest_cpu = cpumask_first(sched_group_span(idlest));
10022 : if (cpu_to_node(idlest_cpu) == p->numa_preferred_nid)
10023 : return idlest;
10024 : #endif /* CONFIG_NUMA_BALANCING */
10025 : /*
10026 : * Otherwise, keep the task close to the wakeup source
10027 : * and improve locality if the number of running tasks
10028 : * would remain below threshold where an imbalance is
10029 : * allowed while accounting for the possibility the
10030 : * task is pinned to a subset of CPUs. If there is a
10031 : * real need of migration, periodic load balance will
10032 : * take care of it.
10033 : */
10034 : if (p->nr_cpus_allowed != NR_CPUS) {
10035 : struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
10036 :
10037 : cpumask_and(cpus, sched_group_span(local), p->cpus_ptr);
10038 : imb_numa_nr = min(cpumask_weight(cpus), sd->imb_numa_nr);
10039 : }
10040 :
10041 : imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);
10042 : if (!adjust_numa_imbalance(imbalance,
10043 : local_sgs.sum_nr_running + 1,
10044 : imb_numa_nr)) {
10045 : return NULL;
10046 : }
10047 : }
10048 : #endif /* CONFIG_NUMA */
10049 :
10050 : /*
10051 : * Select group with highest number of idle CPUs. We could also
10052 : * compare the utilization which is more stable but it can end
10053 : * up that the group has less spare capacity but finally more
10054 : * idle CPUs which means more opportunity to run task.
10055 : */
10056 : if (local_sgs.idle_cpus >= idlest_sgs.idle_cpus)
10057 : return NULL;
10058 : break;
10059 : }
10060 :
10061 : return idlest;
10062 : }
10063 :
10064 : static void update_idle_cpu_scan(struct lb_env *env,
10065 : unsigned long sum_util)
10066 : {
10067 : struct sched_domain_shared *sd_share;
10068 : int llc_weight, pct;
10069 : u64 x, y, tmp;
10070 : /*
10071 : * Update the number of CPUs to scan in LLC domain, which could
10072 : * be used as a hint in select_idle_cpu(). The update of sd_share
10073 : * could be expensive because it is within a shared cache line.
10074 : * So the write of this hint only occurs during periodic load
10075 : * balancing, rather than CPU_NEWLY_IDLE, because the latter
10076 : * can fire way more frequently than the former.
10077 : */
10078 : if (!sched_feat(SIS_UTIL) || env->idle == CPU_NEWLY_IDLE)
10079 : return;
10080 :
10081 : llc_weight = per_cpu(sd_llc_size, env->dst_cpu);
10082 : if (env->sd->span_weight != llc_weight)
10083 : return;
10084 :
10085 : sd_share = rcu_dereference(per_cpu(sd_llc_shared, env->dst_cpu));
10086 : if (!sd_share)
10087 : return;
10088 :
10089 : /*
10090 : * The number of CPUs to search drops as sum_util increases, when
10091 : * sum_util hits 85% or above, the scan stops.
10092 : * The reason to choose 85% as the threshold is because this is the
10093 : * imbalance_pct(117) when a LLC sched group is overloaded.
10094 : *
10095 : * let y = SCHED_CAPACITY_SCALE - p * x^2 [1]
10096 : * and y'= y / SCHED_CAPACITY_SCALE
10097 : *
10098 : * x is the ratio of sum_util compared to the CPU capacity:
10099 : * x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
10100 : * y' is the ratio of CPUs to be scanned in the LLC domain,
10101 : * and the number of CPUs to scan is calculated by:
10102 : *
10103 : * nr_scan = llc_weight * y' [2]
10104 : *
10105 : * When x hits the threshold of overloaded, AKA, when
10106 : * x = 100 / pct, y drops to 0. According to [1],
10107 : * p should be SCHED_CAPACITY_SCALE * pct^2 / 10000
10108 : *
10109 : * Scale x by SCHED_CAPACITY_SCALE:
10110 : * x' = sum_util / llc_weight; [3]
10111 : *
10112 : * and finally [1] becomes:
10113 : * y = SCHED_CAPACITY_SCALE -
10114 : * x'^2 * pct^2 / (10000 * SCHED_CAPACITY_SCALE) [4]
10115 : *
10116 : */
10117 : /* equation [3] */
10118 : x = sum_util;
10119 : do_div(x, llc_weight);
10120 :
10121 : /* equation [4] */
10122 : pct = env->sd->imbalance_pct;
10123 : tmp = x * x * pct * pct;
10124 : do_div(tmp, 10000 * SCHED_CAPACITY_SCALE);
10125 : tmp = min_t(long, tmp, SCHED_CAPACITY_SCALE);
10126 : y = SCHED_CAPACITY_SCALE - tmp;
10127 :
10128 : /* equation [2] */
10129 : y *= llc_weight;
10130 : do_div(y, SCHED_CAPACITY_SCALE);
10131 : if ((int)y != sd_share->nr_idle_scan)
10132 : WRITE_ONCE(sd_share->nr_idle_scan, (int)y);
10133 : }
10134 :
10135 : /**
10136 : * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
10137 : * @env: The load balancing environment.
10138 : * @sds: variable to hold the statistics for this sched_domain.
10139 : */
10140 :
10141 : static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
10142 : {
10143 : struct sched_group *sg = env->sd->groups;
10144 : struct sg_lb_stats *local = &sds->local_stat;
10145 : struct sg_lb_stats tmp_sgs;
10146 : unsigned long sum_util = 0;
10147 : int sg_status = 0;
10148 :
10149 : do {
10150 : struct sg_lb_stats *sgs = &tmp_sgs;
10151 : int local_group;
10152 :
10153 : local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(sg));
10154 : if (local_group) {
10155 : sds->local = sg;
10156 : sgs = local;
10157 :
10158 : if (env->idle != CPU_NEWLY_IDLE ||
10159 : time_after_eq(jiffies, sg->sgc->next_update))
10160 : update_group_capacity(env->sd, env->dst_cpu);
10161 : }
10162 :
10163 : update_sg_lb_stats(env, sds, sg, sgs, &sg_status);
10164 :
10165 : if (local_group)
10166 : goto next_group;
10167 :
10168 :
10169 : if (update_sd_pick_busiest(env, sds, sg, sgs)) {
10170 : sds->busiest = sg;
10171 : sds->busiest_stat = *sgs;
10172 : }
10173 :
10174 : next_group:
10175 : /* Now, start updating sd_lb_stats */
10176 : sds->total_load += sgs->group_load;
10177 : sds->total_capacity += sgs->group_capacity;
10178 :
10179 : sum_util += sgs->group_util;
10180 : sg = sg->next;
10181 : } while (sg != env->sd->groups);
10182 :
10183 : /*
10184 : * Indicate that the child domain of the busiest group prefers tasks
10185 : * go to a child's sibling domains first. NB the flags of a sched group
10186 : * are those of the child domain.
10187 : */
10188 : if (sds->busiest)
10189 : sds->prefer_sibling = !!(sds->busiest->flags & SD_PREFER_SIBLING);
10190 :
10191 :
10192 : if (env->sd->flags & SD_NUMA)
10193 : env->fbq_type = fbq_classify_group(&sds->busiest_stat);
10194 :
10195 : if (!env->sd->parent) {
10196 : struct root_domain *rd = env->dst_rq->rd;
10197 :
10198 : /* update overload indicator if we are at root domain */
10199 : WRITE_ONCE(rd->overload, sg_status & SG_OVERLOAD);
10200 :
10201 : /* Update over-utilization (tipping point, U >= 0) indicator */
10202 : WRITE_ONCE(rd->overutilized, sg_status & SG_OVERUTILIZED);
10203 : trace_sched_overutilized_tp(rd, sg_status & SG_OVERUTILIZED);
10204 : } else if (sg_status & SG_OVERUTILIZED) {
10205 : struct root_domain *rd = env->dst_rq->rd;
10206 :
10207 : WRITE_ONCE(rd->overutilized, SG_OVERUTILIZED);
10208 : trace_sched_overutilized_tp(rd, SG_OVERUTILIZED);
10209 : }
10210 :
10211 : update_idle_cpu_scan(env, sum_util);
10212 : }
10213 :
10214 : /**
10215 : * calculate_imbalance - Calculate the amount of imbalance present within the
10216 : * groups of a given sched_domain during load balance.
10217 : * @env: load balance environment
10218 : * @sds: statistics of the sched_domain whose imbalance is to be calculated.
10219 : */
10220 : static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
10221 : {
10222 : struct sg_lb_stats *local, *busiest;
10223 :
10224 : local = &sds->local_stat;
10225 : busiest = &sds->busiest_stat;
10226 :
10227 : if (busiest->group_type == group_misfit_task) {
10228 : if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
10229 : /* Set imbalance to allow misfit tasks to be balanced. */
10230 : env->migration_type = migrate_misfit;
10231 : env->imbalance = 1;
10232 : } else {
10233 : /*
10234 : * Set load imbalance to allow moving task from cpu
10235 : * with reduced capacity.
10236 : */
10237 : env->migration_type = migrate_load;
10238 : env->imbalance = busiest->group_misfit_task_load;
10239 : }
10240 : return;
10241 : }
10242 :
10243 : if (busiest->group_type == group_asym_packing) {
10244 : /*
10245 : * In case of asym capacity, we will try to migrate all load to
10246 : * the preferred CPU.
10247 : */
10248 : env->migration_type = migrate_task;
10249 : env->imbalance = busiest->sum_h_nr_running;
10250 : return;
10251 : }
10252 :
10253 : if (busiest->group_type == group_imbalanced) {
10254 : /*
10255 : * In the group_imb case we cannot rely on group-wide averages
10256 : * to ensure CPU-load equilibrium, try to move any task to fix
10257 : * the imbalance. The next load balance will take care of
10258 : * balancing back the system.
10259 : */
10260 : env->migration_type = migrate_task;
10261 : env->imbalance = 1;
10262 : return;
10263 : }
10264 :
10265 : /*
10266 : * Try to use spare capacity of local group without overloading it or
10267 : * emptying busiest.
10268 : */
10269 : if (local->group_type == group_has_spare) {
10270 : if ((busiest->group_type > group_fully_busy) &&
10271 : !(env->sd->flags & SD_SHARE_PKG_RESOURCES)) {
10272 : /*
10273 : * If busiest is overloaded, try to fill spare
10274 : * capacity. This might end up creating spare capacity
10275 : * in busiest or busiest still being overloaded but
10276 : * there is no simple way to directly compute the
10277 : * amount of load to migrate in order to balance the
10278 : * system.
10279 : */
10280 : env->migration_type = migrate_util;
10281 : env->imbalance = max(local->group_capacity, local->group_util) -
10282 : local->group_util;
10283 :
10284 : /*
10285 : * In some cases, the group's utilization is max or even
10286 : * higher than capacity because of migrations but the
10287 : * local CPU is (newly) idle. There is at least one
10288 : * waiting task in this overloaded busiest group. Let's
10289 : * try to pull it.
10290 : */
10291 : if (env->idle != CPU_NOT_IDLE && env->imbalance == 0) {
10292 : env->migration_type = migrate_task;
10293 : env->imbalance = 1;
10294 : }
10295 :
10296 : return;
10297 : }
10298 :
10299 : if (busiest->group_weight == 1 || sds->prefer_sibling) {
10300 : unsigned int nr_diff = busiest->sum_nr_running;
10301 : /*
10302 : * When prefer sibling, evenly spread running tasks on
10303 : * groups.
10304 : */
10305 : env->migration_type = migrate_task;
10306 : lsub_positive(&nr_diff, local->sum_nr_running);
10307 : env->imbalance = nr_diff;
10308 : } else {
10309 :
10310 : /*
10311 : * If there is no overload, we just want to even the number of
10312 : * idle cpus.
10313 : */
10314 : env->migration_type = migrate_task;
10315 : env->imbalance = max_t(long, 0,
10316 : (local->idle_cpus - busiest->idle_cpus));
10317 : }
10318 :
10319 : #ifdef CONFIG_NUMA
10320 : /* Consider allowing a small imbalance between NUMA groups */
10321 : if (env->sd->flags & SD_NUMA) {
10322 : env->imbalance = adjust_numa_imbalance(env->imbalance,
10323 : local->sum_nr_running + 1,
10324 : env->sd->imb_numa_nr);
10325 : }
10326 : #endif
10327 :
10328 : /* Number of tasks to move to restore balance */
10329 : env->imbalance >>= 1;
10330 :
10331 : return;
10332 : }
10333 :
10334 : /*
10335 : * Local is fully busy but has to take more load to relieve the
10336 : * busiest group
10337 : */
10338 : if (local->group_type < group_overloaded) {
10339 : /*
10340 : * Local will become overloaded so the avg_load metrics are
10341 : * finally needed.
10342 : */
10343 :
10344 : local->avg_load = (local->group_load * SCHED_CAPACITY_SCALE) /
10345 : local->group_capacity;
10346 :
10347 : /*
10348 : * If the local group is more loaded than the selected
10349 : * busiest group don't try to pull any tasks.
10350 : */
10351 : if (local->avg_load >= busiest->avg_load) {
10352 : env->imbalance = 0;
10353 : return;
10354 : }
10355 :
10356 : sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
10357 : sds->total_capacity;
10358 :
10359 : /*
10360 : * If the local group is more loaded than the average system
10361 : * load, don't try to pull any tasks.
10362 : */
10363 : if (local->avg_load >= sds->avg_load) {
10364 : env->imbalance = 0;
10365 : return;
10366 : }
10367 :
10368 : }
10369 :
10370 : /*
10371 : * Both group are or will become overloaded and we're trying to get all
10372 : * the CPUs to the average_load, so we don't want to push ourselves
10373 : * above the average load, nor do we wish to reduce the max loaded CPU
10374 : * below the average load. At the same time, we also don't want to
10375 : * reduce the group load below the group capacity. Thus we look for
10376 : * the minimum possible imbalance.
10377 : */
10378 : env->migration_type = migrate_load;
10379 : env->imbalance = min(
10380 : (busiest->avg_load - sds->avg_load) * busiest->group_capacity,
10381 : (sds->avg_load - local->avg_load) * local->group_capacity
10382 : ) / SCHED_CAPACITY_SCALE;
10383 : }
10384 :
10385 : /******* find_busiest_group() helpers end here *********************/
10386 :
10387 : /*
10388 : * Decision matrix according to the local and busiest group type:
10389 : *
10390 : * busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
10391 : * has_spare nr_idle balanced N/A N/A balanced balanced
10392 : * fully_busy nr_idle nr_idle N/A N/A balanced balanced
10393 : * misfit_task force N/A N/A N/A N/A N/A
10394 : * asym_packing force force N/A N/A force force
10395 : * imbalanced force force N/A N/A force force
10396 : * overloaded force force N/A N/A force avg_load
10397 : *
10398 : * N/A : Not Applicable because already filtered while updating
10399 : * statistics.
10400 : * balanced : The system is balanced for these 2 groups.
10401 : * force : Calculate the imbalance as load migration is probably needed.
10402 : * avg_load : Only if imbalance is significant enough.
10403 : * nr_idle : dst_cpu is not busy and the number of idle CPUs is quite
10404 : * different in groups.
10405 : */
10406 :
10407 : /**
10408 : * find_busiest_group - Returns the busiest group within the sched_domain
10409 : * if there is an imbalance.
10410 : * @env: The load balancing environment.
10411 : *
10412 : * Also calculates the amount of runnable load which should be moved
10413 : * to restore balance.
10414 : *
10415 : * Return: - The busiest group if imbalance exists.
10416 : */
10417 : static struct sched_group *find_busiest_group(struct lb_env *env)
10418 : {
10419 : struct sg_lb_stats *local, *busiest;
10420 : struct sd_lb_stats sds;
10421 :
10422 : init_sd_lb_stats(&sds);
10423 :
10424 : /*
10425 : * Compute the various statistics relevant for load balancing at
10426 : * this level.
10427 : */
10428 : update_sd_lb_stats(env, &sds);
10429 :
10430 : /* There is no busy sibling group to pull tasks from */
10431 : if (!sds.busiest)
10432 : goto out_balanced;
10433 :
10434 : busiest = &sds.busiest_stat;
10435 :
10436 : /* Misfit tasks should be dealt with regardless of the avg load */
10437 : if (busiest->group_type == group_misfit_task)
10438 : goto force_balance;
10439 :
10440 : if (sched_energy_enabled()) {
10441 : struct root_domain *rd = env->dst_rq->rd;
10442 :
10443 : if (rcu_dereference(rd->pd) && !READ_ONCE(rd->overutilized))
10444 : goto out_balanced;
10445 : }
10446 :
10447 : /* ASYM feature bypasses nice load balance check */
10448 : if (busiest->group_type == group_asym_packing)
10449 : goto force_balance;
10450 :
10451 : /*
10452 : * If the busiest group is imbalanced the below checks don't
10453 : * work because they assume all things are equal, which typically
10454 : * isn't true due to cpus_ptr constraints and the like.
10455 : */
10456 : if (busiest->group_type == group_imbalanced)
10457 : goto force_balance;
10458 :
10459 : local = &sds.local_stat;
10460 : /*
10461 : * If the local group is busier than the selected busiest group
10462 : * don't try and pull any tasks.
10463 : */
10464 : if (local->group_type > busiest->group_type)
10465 : goto out_balanced;
10466 :
10467 : /*
10468 : * When groups are overloaded, use the avg_load to ensure fairness
10469 : * between tasks.
10470 : */
10471 : if (local->group_type == group_overloaded) {
10472 : /*
10473 : * If the local group is more loaded than the selected
10474 : * busiest group don't try to pull any tasks.
10475 : */
10476 : if (local->avg_load >= busiest->avg_load)
10477 : goto out_balanced;
10478 :
10479 : /* XXX broken for overlapping NUMA groups */
10480 : sds.avg_load = (sds.total_load * SCHED_CAPACITY_SCALE) /
10481 : sds.total_capacity;
10482 :
10483 : /*
10484 : * Don't pull any tasks if this group is already above the
10485 : * domain average load.
10486 : */
10487 : if (local->avg_load >= sds.avg_load)
10488 : goto out_balanced;
10489 :
10490 : /*
10491 : * If the busiest group is more loaded, use imbalance_pct to be
10492 : * conservative.
10493 : */
10494 : if (100 * busiest->avg_load <=
10495 : env->sd->imbalance_pct * local->avg_load)
10496 : goto out_balanced;
10497 : }
10498 :
10499 : /*
10500 : * Try to move all excess tasks to a sibling domain of the busiest
10501 : * group's child domain.
10502 : */
10503 : if (sds.prefer_sibling && local->group_type == group_has_spare &&
10504 : busiest->sum_nr_running > local->sum_nr_running + 1)
10505 : goto force_balance;
10506 :
10507 : if (busiest->group_type != group_overloaded) {
10508 : if (env->idle == CPU_NOT_IDLE)
10509 : /*
10510 : * If the busiest group is not overloaded (and as a
10511 : * result the local one too) but this CPU is already
10512 : * busy, let another idle CPU try to pull task.
10513 : */
10514 : goto out_balanced;
10515 :
10516 : if (busiest->group_weight > 1 &&
10517 : local->idle_cpus <= (busiest->idle_cpus + 1))
10518 : /*
10519 : * If the busiest group is not overloaded
10520 : * and there is no imbalance between this and busiest
10521 : * group wrt idle CPUs, it is balanced. The imbalance
10522 : * becomes significant if the diff is greater than 1
10523 : * otherwise we might end up to just move the imbalance
10524 : * on another group. Of course this applies only if
10525 : * there is more than 1 CPU per group.
10526 : */
10527 : goto out_balanced;
10528 :
10529 : if (busiest->sum_h_nr_running == 1)
10530 : /*
10531 : * busiest doesn't have any tasks waiting to run
10532 : */
10533 : goto out_balanced;
10534 : }
10535 :
10536 : force_balance:
10537 : /* Looks like there is an imbalance. Compute it */
10538 : calculate_imbalance(env, &sds);
10539 : return env->imbalance ? sds.busiest : NULL;
10540 :
10541 : out_balanced:
10542 : env->imbalance = 0;
10543 : return NULL;
10544 : }
10545 :
10546 : /*
10547 : * find_busiest_queue - find the busiest runqueue among the CPUs in the group.
10548 : */
10549 : static struct rq *find_busiest_queue(struct lb_env *env,
10550 : struct sched_group *group)
10551 : {
10552 : struct rq *busiest = NULL, *rq;
10553 : unsigned long busiest_util = 0, busiest_load = 0, busiest_capacity = 1;
10554 : unsigned int busiest_nr = 0;
10555 : int i;
10556 :
10557 : for_each_cpu_and(i, sched_group_span(group), env->cpus) {
10558 : unsigned long capacity, load, util;
10559 : unsigned int nr_running;
10560 : enum fbq_type rt;
10561 :
10562 : rq = cpu_rq(i);
10563 : rt = fbq_classify_rq(rq);
10564 :
10565 : /*
10566 : * We classify groups/runqueues into three groups:
10567 : * - regular: there are !numa tasks
10568 : * - remote: there are numa tasks that run on the 'wrong' node
10569 : * - all: there is no distinction
10570 : *
10571 : * In order to avoid migrating ideally placed numa tasks,
10572 : * ignore those when there's better options.
10573 : *
10574 : * If we ignore the actual busiest queue to migrate another
10575 : * task, the next balance pass can still reduce the busiest
10576 : * queue by moving tasks around inside the node.
10577 : *
10578 : * If we cannot move enough load due to this classification
10579 : * the next pass will adjust the group classification and
10580 : * allow migration of more tasks.
10581 : *
10582 : * Both cases only affect the total convergence complexity.
10583 : */
10584 : if (rt > env->fbq_type)
10585 : continue;
10586 :
10587 : nr_running = rq->cfs.h_nr_running;
10588 : if (!nr_running)
10589 : continue;
10590 :
10591 : capacity = capacity_of(i);
10592 :
10593 : /*
10594 : * For ASYM_CPUCAPACITY domains, don't pick a CPU that could
10595 : * eventually lead to active_balancing high->low capacity.
10596 : * Higher per-CPU capacity is considered better than balancing
10597 : * average load.
10598 : */
10599 : if (env->sd->flags & SD_ASYM_CPUCAPACITY &&
10600 : !capacity_greater(capacity_of(env->dst_cpu), capacity) &&
10601 : nr_running == 1)
10602 : continue;
10603 :
10604 : /*
10605 : * Make sure we only pull tasks from a CPU of lower priority
10606 : * when balancing between SMT siblings.
10607 : *
10608 : * If balancing between cores, let lower priority CPUs help
10609 : * SMT cores with more than one busy sibling.
10610 : */
10611 : if ((env->sd->flags & SD_ASYM_PACKING) &&
10612 : sched_use_asym_prio(env->sd, i) &&
10613 : sched_asym_prefer(i, env->dst_cpu) &&
10614 : nr_running == 1)
10615 : continue;
10616 :
10617 : switch (env->migration_type) {
10618 : case migrate_load:
10619 : /*
10620 : * When comparing with load imbalance, use cpu_load()
10621 : * which is not scaled with the CPU capacity.
10622 : */
10623 : load = cpu_load(rq);
10624 :
10625 : if (nr_running == 1 && load > env->imbalance &&
10626 : !check_cpu_capacity(rq, env->sd))
10627 : break;
10628 :
10629 : /*
10630 : * For the load comparisons with the other CPUs,
10631 : * consider the cpu_load() scaled with the CPU
10632 : * capacity, so that the load can be moved away
10633 : * from the CPU that is potentially running at a
10634 : * lower capacity.
10635 : *
10636 : * Thus we're looking for max(load_i / capacity_i),
10637 : * crosswise multiplication to rid ourselves of the
10638 : * division works out to:
10639 : * load_i * capacity_j > load_j * capacity_i;
10640 : * where j is our previous maximum.
10641 : */
10642 : if (load * busiest_capacity > busiest_load * capacity) {
10643 : busiest_load = load;
10644 : busiest_capacity = capacity;
10645 : busiest = rq;
10646 : }
10647 : break;
10648 :
10649 : case migrate_util:
10650 : util = cpu_util_cfs_boost(i);
10651 :
10652 : /*
10653 : * Don't try to pull utilization from a CPU with one
10654 : * running task. Whatever its utilization, we will fail
10655 : * detach the task.
10656 : */
10657 : if (nr_running <= 1)
10658 : continue;
10659 :
10660 : if (busiest_util < util) {
10661 : busiest_util = util;
10662 : busiest = rq;
10663 : }
10664 : break;
10665 :
10666 : case migrate_task:
10667 : if (busiest_nr < nr_running) {
10668 : busiest_nr = nr_running;
10669 : busiest = rq;
10670 : }
10671 : break;
10672 :
10673 : case migrate_misfit:
10674 : /*
10675 : * For ASYM_CPUCAPACITY domains with misfit tasks we
10676 : * simply seek the "biggest" misfit task.
10677 : */
10678 : if (rq->misfit_task_load > busiest_load) {
10679 : busiest_load = rq->misfit_task_load;
10680 : busiest = rq;
10681 : }
10682 :
10683 : break;
10684 :
10685 : }
10686 : }
10687 :
10688 : return busiest;
10689 : }
10690 :
10691 : /*
10692 : * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
10693 : * so long as it is large enough.
10694 : */
10695 : #define MAX_PINNED_INTERVAL 512
10696 :
10697 : static inline bool
10698 : asym_active_balance(struct lb_env *env)
10699 : {
10700 : /*
10701 : * ASYM_PACKING needs to force migrate tasks from busy but lower
10702 : * priority CPUs in order to pack all tasks in the highest priority
10703 : * CPUs. When done between cores, do it only if the whole core if the
10704 : * whole core is idle.
10705 : *
10706 : * If @env::src_cpu is an SMT core with busy siblings, let
10707 : * the lower priority @env::dst_cpu help it. Do not follow
10708 : * CPU priority.
10709 : */
10710 : return env->idle != CPU_NOT_IDLE && (env->sd->flags & SD_ASYM_PACKING) &&
10711 : sched_use_asym_prio(env->sd, env->dst_cpu) &&
10712 : (sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
10713 : !sched_use_asym_prio(env->sd, env->src_cpu));
10714 : }
10715 :
10716 : static inline bool
10717 : imbalanced_active_balance(struct lb_env *env)
10718 : {
10719 : struct sched_domain *sd = env->sd;
10720 :
10721 : /*
10722 : * The imbalanced case includes the case of pinned tasks preventing a fair
10723 : * distribution of the load on the system but also the even distribution of the
10724 : * threads on a system with spare capacity
10725 : */
10726 : if ((env->migration_type == migrate_task) &&
10727 : (sd->nr_balance_failed > sd->cache_nice_tries+2))
10728 : return 1;
10729 :
10730 : return 0;
10731 : }
10732 :
10733 : static int need_active_balance(struct lb_env *env)
10734 : {
10735 : struct sched_domain *sd = env->sd;
10736 :
10737 : if (asym_active_balance(env))
10738 : return 1;
10739 :
10740 : if (imbalanced_active_balance(env))
10741 : return 1;
10742 :
10743 : /*
10744 : * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
10745 : * It's worth migrating the task if the src_cpu's capacity is reduced
10746 : * because of other sched_class or IRQs if more capacity stays
10747 : * available on dst_cpu.
10748 : */
10749 : if ((env->idle != CPU_NOT_IDLE) &&
10750 : (env->src_rq->cfs.h_nr_running == 1)) {
10751 : if ((check_cpu_capacity(env->src_rq, sd)) &&
10752 : (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100))
10753 : return 1;
10754 : }
10755 :
10756 : if (env->migration_type == migrate_misfit)
10757 : return 1;
10758 :
10759 : return 0;
10760 : }
10761 :
10762 : static int active_load_balance_cpu_stop(void *data);
10763 :
10764 : static int should_we_balance(struct lb_env *env)
10765 : {
10766 : struct sched_group *sg = env->sd->groups;
10767 : int cpu;
10768 :
10769 : /*
10770 : * Ensure the balancing environment is consistent; can happen
10771 : * when the softirq triggers 'during' hotplug.
10772 : */
10773 : if (!cpumask_test_cpu(env->dst_cpu, env->cpus))
10774 : return 0;
10775 :
10776 : /*
10777 : * In the newly idle case, we will allow all the CPUs
10778 : * to do the newly idle load balance.
10779 : *
10780 : * However, we bail out if we already have tasks or a wakeup pending,
10781 : * to optimize wakeup latency.
10782 : */
10783 : if (env->idle == CPU_NEWLY_IDLE) {
10784 : if (env->dst_rq->nr_running > 0 || env->dst_rq->ttwu_pending)
10785 : return 0;
10786 : return 1;
10787 : }
10788 :
10789 : /* Try to find first idle CPU */
10790 : for_each_cpu_and(cpu, group_balance_mask(sg), env->cpus) {
10791 : if (!idle_cpu(cpu))
10792 : continue;
10793 :
10794 : /* Are we the first idle CPU? */
10795 : return cpu == env->dst_cpu;
10796 : }
10797 :
10798 : /* Are we the first CPU of this group ? */
10799 : return group_balance_cpu(sg) == env->dst_cpu;
10800 : }
10801 :
10802 : /*
10803 : * Check this_cpu to ensure it is balanced within domain. Attempt to move
10804 : * tasks if there is an imbalance.
10805 : */
10806 : static int load_balance(int this_cpu, struct rq *this_rq,
10807 : struct sched_domain *sd, enum cpu_idle_type idle,
10808 : int *continue_balancing)
10809 : {
10810 : int ld_moved, cur_ld_moved, active_balance = 0;
10811 : struct sched_domain *sd_parent = sd->parent;
10812 : struct sched_group *group;
10813 : struct rq *busiest;
10814 : struct rq_flags rf;
10815 : struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
10816 : struct lb_env env = {
10817 : .sd = sd,
10818 : .dst_cpu = this_cpu,
10819 : .dst_rq = this_rq,
10820 : .dst_grpmask = group_balance_mask(sd->groups),
10821 : .idle = idle,
10822 : .loop_break = SCHED_NR_MIGRATE_BREAK,
10823 : .cpus = cpus,
10824 : .fbq_type = all,
10825 : .tasks = LIST_HEAD_INIT(env.tasks),
10826 : };
10827 :
10828 : cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
10829 :
10830 : schedstat_inc(sd->lb_count[idle]);
10831 :
10832 : redo:
10833 : if (!should_we_balance(&env)) {
10834 : *continue_balancing = 0;
10835 : goto out_balanced;
10836 : }
10837 :
10838 : group = find_busiest_group(&env);
10839 : if (!group) {
10840 : schedstat_inc(sd->lb_nobusyg[idle]);
10841 : goto out_balanced;
10842 : }
10843 :
10844 : busiest = find_busiest_queue(&env, group);
10845 : if (!busiest) {
10846 : schedstat_inc(sd->lb_nobusyq[idle]);
10847 : goto out_balanced;
10848 : }
10849 :
10850 : WARN_ON_ONCE(busiest == env.dst_rq);
10851 :
10852 : schedstat_add(sd->lb_imbalance[idle], env.imbalance);
10853 :
10854 : env.src_cpu = busiest->cpu;
10855 : env.src_rq = busiest;
10856 :
10857 : ld_moved = 0;
10858 : /* Clear this flag as soon as we find a pullable task */
10859 : env.flags |= LBF_ALL_PINNED;
10860 : if (busiest->nr_running > 1) {
10861 : /*
10862 : * Attempt to move tasks. If find_busiest_group has found
10863 : * an imbalance but busiest->nr_running <= 1, the group is
10864 : * still unbalanced. ld_moved simply stays zero, so it is
10865 : * correctly treated as an imbalance.
10866 : */
10867 : env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
10868 :
10869 : more_balance:
10870 : rq_lock_irqsave(busiest, &rf);
10871 : update_rq_clock(busiest);
10872 :
10873 : /*
10874 : * cur_ld_moved - load moved in current iteration
10875 : * ld_moved - cumulative load moved across iterations
10876 : */
10877 : cur_ld_moved = detach_tasks(&env);
10878 :
10879 : /*
10880 : * We've detached some tasks from busiest_rq. Every
10881 : * task is masked "TASK_ON_RQ_MIGRATING", so we can safely
10882 : * unlock busiest->lock, and we are able to be sure
10883 : * that nobody can manipulate the tasks in parallel.
10884 : * See task_rq_lock() family for the details.
10885 : */
10886 :
10887 : rq_unlock(busiest, &rf);
10888 :
10889 : if (cur_ld_moved) {
10890 : attach_tasks(&env);
10891 : ld_moved += cur_ld_moved;
10892 : }
10893 :
10894 : local_irq_restore(rf.flags);
10895 :
10896 : if (env.flags & LBF_NEED_BREAK) {
10897 : env.flags &= ~LBF_NEED_BREAK;
10898 : /* Stop if we tried all running tasks */
10899 : if (env.loop < busiest->nr_running)
10900 : goto more_balance;
10901 : }
10902 :
10903 : /*
10904 : * Revisit (affine) tasks on src_cpu that couldn't be moved to
10905 : * us and move them to an alternate dst_cpu in our sched_group
10906 : * where they can run. The upper limit on how many times we
10907 : * iterate on same src_cpu is dependent on number of CPUs in our
10908 : * sched_group.
10909 : *
10910 : * This changes load balance semantics a bit on who can move
10911 : * load to a given_cpu. In addition to the given_cpu itself
10912 : * (or a ilb_cpu acting on its behalf where given_cpu is
10913 : * nohz-idle), we now have balance_cpu in a position to move
10914 : * load to given_cpu. In rare situations, this may cause
10915 : * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
10916 : * _independently_ and at _same_ time to move some load to
10917 : * given_cpu) causing excess load to be moved to given_cpu.
10918 : * This however should not happen so much in practice and
10919 : * moreover subsequent load balance cycles should correct the
10920 : * excess load moved.
10921 : */
10922 : if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {
10923 :
10924 : /* Prevent to re-select dst_cpu via env's CPUs */
10925 : __cpumask_clear_cpu(env.dst_cpu, env.cpus);
10926 :
10927 : env.dst_rq = cpu_rq(env.new_dst_cpu);
10928 : env.dst_cpu = env.new_dst_cpu;
10929 : env.flags &= ~LBF_DST_PINNED;
10930 : env.loop = 0;
10931 : env.loop_break = SCHED_NR_MIGRATE_BREAK;
10932 :
10933 : /*
10934 : * Go back to "more_balance" rather than "redo" since we
10935 : * need to continue with same src_cpu.
10936 : */
10937 : goto more_balance;
10938 : }
10939 :
10940 : /*
10941 : * We failed to reach balance because of affinity.
10942 : */
10943 : if (sd_parent) {
10944 : int *group_imbalance = &sd_parent->groups->sgc->imbalance;
10945 :
10946 : if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0)
10947 : *group_imbalance = 1;
10948 : }
10949 :
10950 : /* All tasks on this runqueue were pinned by CPU affinity */
10951 : if (unlikely(env.flags & LBF_ALL_PINNED)) {
10952 : __cpumask_clear_cpu(cpu_of(busiest), cpus);
10953 : /*
10954 : * Attempting to continue load balancing at the current
10955 : * sched_domain level only makes sense if there are
10956 : * active CPUs remaining as possible busiest CPUs to
10957 : * pull load from which are not contained within the
10958 : * destination group that is receiving any migrated
10959 : * load.
10960 : */
10961 : if (!cpumask_subset(cpus, env.dst_grpmask)) {
10962 : env.loop = 0;
10963 : env.loop_break = SCHED_NR_MIGRATE_BREAK;
10964 : goto redo;
10965 : }
10966 : goto out_all_pinned;
10967 : }
10968 : }
10969 :
10970 : if (!ld_moved) {
10971 : schedstat_inc(sd->lb_failed[idle]);
10972 : /*
10973 : * Increment the failure counter only on periodic balance.
10974 : * We do not want newidle balance, which can be very
10975 : * frequent, pollute the failure counter causing
10976 : * excessive cache_hot migrations and active balances.
10977 : */
10978 : if (idle != CPU_NEWLY_IDLE)
10979 : sd->nr_balance_failed++;
10980 :
10981 : if (need_active_balance(&env)) {
10982 : unsigned long flags;
10983 :
10984 : raw_spin_rq_lock_irqsave(busiest, flags);
10985 :
10986 : /*
10987 : * Don't kick the active_load_balance_cpu_stop,
10988 : * if the curr task on busiest CPU can't be
10989 : * moved to this_cpu:
10990 : */
10991 : if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) {
10992 : raw_spin_rq_unlock_irqrestore(busiest, flags);
10993 : goto out_one_pinned;
10994 : }
10995 :
10996 : /* Record that we found at least one task that could run on this_cpu */
10997 : env.flags &= ~LBF_ALL_PINNED;
10998 :
10999 : /*
11000 : * ->active_balance synchronizes accesses to
11001 : * ->active_balance_work. Once set, it's cleared
11002 : * only after active load balance is finished.
11003 : */
11004 : if (!busiest->active_balance) {
11005 : busiest->active_balance = 1;
11006 : busiest->push_cpu = this_cpu;
11007 : active_balance = 1;
11008 : }
11009 : raw_spin_rq_unlock_irqrestore(busiest, flags);
11010 :
11011 : if (active_balance) {
11012 : stop_one_cpu_nowait(cpu_of(busiest),
11013 : active_load_balance_cpu_stop, busiest,
11014 : &busiest->active_balance_work);
11015 : }
11016 : }
11017 : } else {
11018 : sd->nr_balance_failed = 0;
11019 : }
11020 :
11021 : if (likely(!active_balance) || need_active_balance(&env)) {
11022 : /* We were unbalanced, so reset the balancing interval */
11023 : sd->balance_interval = sd->min_interval;
11024 : }
11025 :
11026 : goto out;
11027 :
11028 : out_balanced:
11029 : /*
11030 : * We reach balance although we may have faced some affinity
11031 : * constraints. Clear the imbalance flag only if other tasks got
11032 : * a chance to move and fix the imbalance.
11033 : */
11034 : if (sd_parent && !(env.flags & LBF_ALL_PINNED)) {
11035 : int *group_imbalance = &sd_parent->groups->sgc->imbalance;
11036 :
11037 : if (*group_imbalance)
11038 : *group_imbalance = 0;
11039 : }
11040 :
11041 : out_all_pinned:
11042 : /*
11043 : * We reach balance because all tasks are pinned at this level so
11044 : * we can't migrate them. Let the imbalance flag set so parent level
11045 : * can try to migrate them.
11046 : */
11047 : schedstat_inc(sd->lb_balanced[idle]);
11048 :
11049 : sd->nr_balance_failed = 0;
11050 :
11051 : out_one_pinned:
11052 : ld_moved = 0;
11053 :
11054 : /*
11055 : * newidle_balance() disregards balance intervals, so we could
11056 : * repeatedly reach this code, which would lead to balance_interval
11057 : * skyrocketing in a short amount of time. Skip the balance_interval
11058 : * increase logic to avoid that.
11059 : */
11060 : if (env.idle == CPU_NEWLY_IDLE)
11061 : goto out;
11062 :
11063 : /* tune up the balancing interval */
11064 : if ((env.flags & LBF_ALL_PINNED &&
11065 : sd->balance_interval < MAX_PINNED_INTERVAL) ||
11066 : sd->balance_interval < sd->max_interval)
11067 : sd->balance_interval *= 2;
11068 : out:
11069 : return ld_moved;
11070 : }
11071 :
11072 : static inline unsigned long
11073 : get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
11074 : {
11075 : unsigned long interval = sd->balance_interval;
11076 :
11077 : if (cpu_busy)
11078 : interval *= sd->busy_factor;
11079 :
11080 : /* scale ms to jiffies */
11081 : interval = msecs_to_jiffies(interval);
11082 :
11083 : /*
11084 : * Reduce likelihood of busy balancing at higher domains racing with
11085 : * balancing at lower domains by preventing their balancing periods
11086 : * from being multiples of each other.
11087 : */
11088 : if (cpu_busy)
11089 : interval -= 1;
11090 :
11091 : interval = clamp(interval, 1UL, max_load_balance_interval);
11092 :
11093 : return interval;
11094 : }
11095 :
11096 : static inline void
11097 : update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
11098 : {
11099 : unsigned long interval, next;
11100 :
11101 : /* used by idle balance, so cpu_busy = 0 */
11102 : interval = get_sd_balance_interval(sd, 0);
11103 : next = sd->last_balance + interval;
11104 :
11105 : if (time_after(*next_balance, next))
11106 : *next_balance = next;
11107 : }
11108 :
11109 : /*
11110 : * active_load_balance_cpu_stop is run by the CPU stopper. It pushes
11111 : * running tasks off the busiest CPU onto idle CPUs. It requires at
11112 : * least 1 task to be running on each physical CPU where possible, and
11113 : * avoids physical / logical imbalances.
11114 : */
11115 : static int active_load_balance_cpu_stop(void *data)
11116 : {
11117 : struct rq *busiest_rq = data;
11118 : int busiest_cpu = cpu_of(busiest_rq);
11119 : int target_cpu = busiest_rq->push_cpu;
11120 : struct rq *target_rq = cpu_rq(target_cpu);
11121 : struct sched_domain *sd;
11122 : struct task_struct *p = NULL;
11123 : struct rq_flags rf;
11124 :
11125 : rq_lock_irq(busiest_rq, &rf);
11126 : /*
11127 : * Between queueing the stop-work and running it is a hole in which
11128 : * CPUs can become inactive. We should not move tasks from or to
11129 : * inactive CPUs.
11130 : */
11131 : if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
11132 : goto out_unlock;
11133 :
11134 : /* Make sure the requested CPU hasn't gone down in the meantime: */
11135 : if (unlikely(busiest_cpu != smp_processor_id() ||
11136 : !busiest_rq->active_balance))
11137 : goto out_unlock;
11138 :
11139 : /* Is there any task to move? */
11140 : if (busiest_rq->nr_running <= 1)
11141 : goto out_unlock;
11142 :
11143 : /*
11144 : * This condition is "impossible", if it occurs
11145 : * we need to fix it. Originally reported by
11146 : * Bjorn Helgaas on a 128-CPU setup.
11147 : */
11148 : WARN_ON_ONCE(busiest_rq == target_rq);
11149 :
11150 : /* Search for an sd spanning us and the target CPU. */
11151 : rcu_read_lock();
11152 : for_each_domain(target_cpu, sd) {
11153 : if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
11154 : break;
11155 : }
11156 :
11157 : if (likely(sd)) {
11158 : struct lb_env env = {
11159 : .sd = sd,
11160 : .dst_cpu = target_cpu,
11161 : .dst_rq = target_rq,
11162 : .src_cpu = busiest_rq->cpu,
11163 : .src_rq = busiest_rq,
11164 : .idle = CPU_IDLE,
11165 : .flags = LBF_ACTIVE_LB,
11166 : };
11167 :
11168 : schedstat_inc(sd->alb_count);
11169 : update_rq_clock(busiest_rq);
11170 :
11171 : p = detach_one_task(&env);
11172 : if (p) {
11173 : schedstat_inc(sd->alb_pushed);
11174 : /* Active balancing done, reset the failure counter. */
11175 : sd->nr_balance_failed = 0;
11176 : } else {
11177 : schedstat_inc(sd->alb_failed);
11178 : }
11179 : }
11180 : rcu_read_unlock();
11181 : out_unlock:
11182 : busiest_rq->active_balance = 0;
11183 : rq_unlock(busiest_rq, &rf);
11184 :
11185 : if (p)
11186 : attach_one_task(target_rq, p);
11187 :
11188 : local_irq_enable();
11189 :
11190 : return 0;
11191 : }
11192 :
11193 : static DEFINE_SPINLOCK(balancing);
11194 :
11195 : /*
11196 : * Scale the max load_balance interval with the number of CPUs in the system.
11197 : * This trades load-balance latency on larger machines for less cross talk.
11198 : */
11199 : void update_max_interval(void)
11200 : {
11201 : max_load_balance_interval = HZ*num_online_cpus()/10;
11202 : }
11203 :
11204 : static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost)
11205 : {
11206 : if (cost > sd->max_newidle_lb_cost) {
11207 : /*
11208 : * Track max cost of a domain to make sure to not delay the
11209 : * next wakeup on the CPU.
11210 : */
11211 : sd->max_newidle_lb_cost = cost;
11212 : sd->last_decay_max_lb_cost = jiffies;
11213 : } else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) {
11214 : /*
11215 : * Decay the newidle max times by ~1% per second to ensure that
11216 : * it is not outdated and the current max cost is actually
11217 : * shorter.
11218 : */
11219 : sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256;
11220 : sd->last_decay_max_lb_cost = jiffies;
11221 :
11222 : return true;
11223 : }
11224 :
11225 : return false;
11226 : }
11227 :
11228 : /*
11229 : * It checks each scheduling domain to see if it is due to be balanced,
11230 : * and initiates a balancing operation if so.
11231 : *
11232 : * Balancing parameters are set up in init_sched_domains.
11233 : */
11234 : static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle)
11235 : {
11236 : int continue_balancing = 1;
11237 : int cpu = rq->cpu;
11238 : int busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
11239 : unsigned long interval;
11240 : struct sched_domain *sd;
11241 : /* Earliest time when we have to do rebalance again */
11242 : unsigned long next_balance = jiffies + 60*HZ;
11243 : int update_next_balance = 0;
11244 : int need_serialize, need_decay = 0;
11245 : u64 max_cost = 0;
11246 :
11247 : rcu_read_lock();
11248 : for_each_domain(cpu, sd) {
11249 : /*
11250 : * Decay the newidle max times here because this is a regular
11251 : * visit to all the domains.
11252 : */
11253 : need_decay = update_newidle_cost(sd, 0);
11254 : max_cost += sd->max_newidle_lb_cost;
11255 :
11256 : /*
11257 : * Stop the load balance at this level. There is another
11258 : * CPU in our sched group which is doing load balancing more
11259 : * actively.
11260 : */
11261 : if (!continue_balancing) {
11262 : if (need_decay)
11263 : continue;
11264 : break;
11265 : }
11266 :
11267 : interval = get_sd_balance_interval(sd, busy);
11268 :
11269 : need_serialize = sd->flags & SD_SERIALIZE;
11270 : if (need_serialize) {
11271 : if (!spin_trylock(&balancing))
11272 : goto out;
11273 : }
11274 :
11275 : if (time_after_eq(jiffies, sd->last_balance + interval)) {
11276 : if (load_balance(cpu, rq, sd, idle, &continue_balancing)) {
11277 : /*
11278 : * The LBF_DST_PINNED logic could have changed
11279 : * env->dst_cpu, so we can't know our idle
11280 : * state even if we migrated tasks. Update it.
11281 : */
11282 : idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
11283 : busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
11284 : }
11285 : sd->last_balance = jiffies;
11286 : interval = get_sd_balance_interval(sd, busy);
11287 : }
11288 : if (need_serialize)
11289 : spin_unlock(&balancing);
11290 : out:
11291 : if (time_after(next_balance, sd->last_balance + interval)) {
11292 : next_balance = sd->last_balance + interval;
11293 : update_next_balance = 1;
11294 : }
11295 : }
11296 : if (need_decay) {
11297 : /*
11298 : * Ensure the rq-wide value also decays but keep it at a
11299 : * reasonable floor to avoid funnies with rq->avg_idle.
11300 : */
11301 : rq->max_idle_balance_cost =
11302 : max((u64)sysctl_sched_migration_cost, max_cost);
11303 : }
11304 : rcu_read_unlock();
11305 :
11306 : /*
11307 : * next_balance will be updated only when there is a need.
11308 : * When the cpu is attached to null domain for ex, it will not be
11309 : * updated.
11310 : */
11311 : if (likely(update_next_balance))
11312 : rq->next_balance = next_balance;
11313 :
11314 : }
11315 :
11316 : static inline int on_null_domain(struct rq *rq)
11317 : {
11318 : return unlikely(!rcu_dereference_sched(rq->sd));
11319 : }
11320 :
11321 : #ifdef CONFIG_NO_HZ_COMMON
11322 : /*
11323 : * idle load balancing details
11324 : * - When one of the busy CPUs notice that there may be an idle rebalancing
11325 : * needed, they will kick the idle load balancer, which then does idle
11326 : * load balancing for all the idle CPUs.
11327 : * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED not set
11328 : * anywhere yet.
11329 : */
11330 :
11331 : static inline int find_new_ilb(void)
11332 : {
11333 : int ilb;
11334 : const struct cpumask *hk_mask;
11335 :
11336 : hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
11337 :
11338 : for_each_cpu_and(ilb, nohz.idle_cpus_mask, hk_mask) {
11339 :
11340 : if (ilb == smp_processor_id())
11341 : continue;
11342 :
11343 : if (idle_cpu(ilb))
11344 : return ilb;
11345 : }
11346 :
11347 : return nr_cpu_ids;
11348 : }
11349 :
11350 : /*
11351 : * Kick a CPU to do the nohz balancing, if it is time for it. We pick any
11352 : * idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
11353 : */
11354 : static void kick_ilb(unsigned int flags)
11355 : {
11356 : int ilb_cpu;
11357 :
11358 : /*
11359 : * Increase nohz.next_balance only when if full ilb is triggered but
11360 : * not if we only update stats.
11361 : */
11362 : if (flags & NOHZ_BALANCE_KICK)
11363 : nohz.next_balance = jiffies+1;
11364 :
11365 : ilb_cpu = find_new_ilb();
11366 :
11367 : if (ilb_cpu >= nr_cpu_ids)
11368 : return;
11369 :
11370 : /*
11371 : * Access to rq::nohz_csd is serialized by NOHZ_KICK_MASK; he who sets
11372 : * the first flag owns it; cleared by nohz_csd_func().
11373 : */
11374 : flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
11375 : if (flags & NOHZ_KICK_MASK)
11376 : return;
11377 :
11378 : /*
11379 : * This way we generate an IPI on the target CPU which
11380 : * is idle. And the softirq performing nohz idle load balance
11381 : * will be run before returning from the IPI.
11382 : */
11383 : smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
11384 : }
11385 :
11386 : /*
11387 : * Current decision point for kicking the idle load balancer in the presence
11388 : * of idle CPUs in the system.
11389 : */
11390 : static void nohz_balancer_kick(struct rq *rq)
11391 : {
11392 : unsigned long now = jiffies;
11393 : struct sched_domain_shared *sds;
11394 : struct sched_domain *sd;
11395 : int nr_busy, i, cpu = rq->cpu;
11396 : unsigned int flags = 0;
11397 :
11398 : if (unlikely(rq->idle_balance))
11399 : return;
11400 :
11401 : /*
11402 : * We may be recently in ticked or tickless idle mode. At the first
11403 : * busy tick after returning from idle, we will update the busy stats.
11404 : */
11405 : nohz_balance_exit_idle(rq);
11406 :
11407 : /*
11408 : * None are in tickless mode and hence no need for NOHZ idle load
11409 : * balancing.
11410 : */
11411 : if (likely(!atomic_read(&nohz.nr_cpus)))
11412 : return;
11413 :
11414 : if (READ_ONCE(nohz.has_blocked) &&
11415 : time_after(now, READ_ONCE(nohz.next_blocked)))
11416 : flags = NOHZ_STATS_KICK;
11417 :
11418 : if (time_before(now, nohz.next_balance))
11419 : goto out;
11420 :
11421 : if (rq->nr_running >= 2) {
11422 : flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
11423 : goto out;
11424 : }
11425 :
11426 : rcu_read_lock();
11427 :
11428 : sd = rcu_dereference(rq->sd);
11429 : if (sd) {
11430 : /*
11431 : * If there's a CFS task and the current CPU has reduced
11432 : * capacity; kick the ILB to see if there's a better CPU to run
11433 : * on.
11434 : */
11435 : if (rq->cfs.h_nr_running >= 1 && check_cpu_capacity(rq, sd)) {
11436 : flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
11437 : goto unlock;
11438 : }
11439 : }
11440 :
11441 : sd = rcu_dereference(per_cpu(sd_asym_packing, cpu));
11442 : if (sd) {
11443 : /*
11444 : * When ASYM_PACKING; see if there's a more preferred CPU
11445 : * currently idle; in which case, kick the ILB to move tasks
11446 : * around.
11447 : *
11448 : * When balancing betwen cores, all the SMT siblings of the
11449 : * preferred CPU must be idle.
11450 : */
11451 : for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
11452 : if (sched_use_asym_prio(sd, i) &&
11453 : sched_asym_prefer(i, cpu)) {
11454 : flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
11455 : goto unlock;
11456 : }
11457 : }
11458 : }
11459 :
11460 : sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, cpu));
11461 : if (sd) {
11462 : /*
11463 : * When ASYM_CPUCAPACITY; see if there's a higher capacity CPU
11464 : * to run the misfit task on.
11465 : */
11466 : if (check_misfit_status(rq, sd)) {
11467 : flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
11468 : goto unlock;
11469 : }
11470 :
11471 : /*
11472 : * For asymmetric systems, we do not want to nicely balance
11473 : * cache use, instead we want to embrace asymmetry and only
11474 : * ensure tasks have enough CPU capacity.
11475 : *
11476 : * Skip the LLC logic because it's not relevant in that case.
11477 : */
11478 : goto unlock;
11479 : }
11480 :
11481 : sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
11482 : if (sds) {
11483 : /*
11484 : * If there is an imbalance between LLC domains (IOW we could
11485 : * increase the overall cache use), we need some less-loaded LLC
11486 : * domain to pull some load. Likewise, we may need to spread
11487 : * load within the current LLC domain (e.g. packed SMT cores but
11488 : * other CPUs are idle). We can't really know from here how busy
11489 : * the others are - so just get a nohz balance going if it looks
11490 : * like this LLC domain has tasks we could move.
11491 : */
11492 : nr_busy = atomic_read(&sds->nr_busy_cpus);
11493 : if (nr_busy > 1) {
11494 : flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
11495 : goto unlock;
11496 : }
11497 : }
11498 : unlock:
11499 : rcu_read_unlock();
11500 : out:
11501 : if (READ_ONCE(nohz.needs_update))
11502 : flags |= NOHZ_NEXT_KICK;
11503 :
11504 : if (flags)
11505 : kick_ilb(flags);
11506 : }
11507 :
11508 : static void set_cpu_sd_state_busy(int cpu)
11509 : {
11510 : struct sched_domain *sd;
11511 :
11512 : rcu_read_lock();
11513 : sd = rcu_dereference(per_cpu(sd_llc, cpu));
11514 :
11515 : if (!sd || !sd->nohz_idle)
11516 : goto unlock;
11517 : sd->nohz_idle = 0;
11518 :
11519 : atomic_inc(&sd->shared->nr_busy_cpus);
11520 : unlock:
11521 : rcu_read_unlock();
11522 : }
11523 :
11524 : void nohz_balance_exit_idle(struct rq *rq)
11525 : {
11526 : SCHED_WARN_ON(rq != this_rq());
11527 :
11528 : if (likely(!rq->nohz_tick_stopped))
11529 : return;
11530 :
11531 : rq->nohz_tick_stopped = 0;
11532 : cpumask_clear_cpu(rq->cpu, nohz.idle_cpus_mask);
11533 : atomic_dec(&nohz.nr_cpus);
11534 :
11535 : set_cpu_sd_state_busy(rq->cpu);
11536 : }
11537 :
11538 : static void set_cpu_sd_state_idle(int cpu)
11539 : {
11540 : struct sched_domain *sd;
11541 :
11542 : rcu_read_lock();
11543 : sd = rcu_dereference(per_cpu(sd_llc, cpu));
11544 :
11545 : if (!sd || sd->nohz_idle)
11546 : goto unlock;
11547 : sd->nohz_idle = 1;
11548 :
11549 : atomic_dec(&sd->shared->nr_busy_cpus);
11550 : unlock:
11551 : rcu_read_unlock();
11552 : }
11553 :
11554 : /*
11555 : * This routine will record that the CPU is going idle with tick stopped.
11556 : * This info will be used in performing idle load balancing in the future.
11557 : */
11558 : void nohz_balance_enter_idle(int cpu)
11559 : {
11560 : struct rq *rq = cpu_rq(cpu);
11561 :
11562 : SCHED_WARN_ON(cpu != smp_processor_id());
11563 :
11564 : /* If this CPU is going down, then nothing needs to be done: */
11565 : if (!cpu_active(cpu))
11566 : return;
11567 :
11568 : /* Spare idle load balancing on CPUs that don't want to be disturbed: */
11569 : if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
11570 : return;
11571 :
11572 : /*
11573 : * Can be set safely without rq->lock held
11574 : * If a clear happens, it will have evaluated last additions because
11575 : * rq->lock is held during the check and the clear
11576 : */
11577 : rq->has_blocked_load = 1;
11578 :
11579 : /*
11580 : * The tick is still stopped but load could have been added in the
11581 : * meantime. We set the nohz.has_blocked flag to trig a check of the
11582 : * *_avg. The CPU is already part of nohz.idle_cpus_mask so the clear
11583 : * of nohz.has_blocked can only happen after checking the new load
11584 : */
11585 : if (rq->nohz_tick_stopped)
11586 : goto out;
11587 :
11588 : /* If we're a completely isolated CPU, we don't play: */
11589 : if (on_null_domain(rq))
11590 : return;
11591 :
11592 : rq->nohz_tick_stopped = 1;
11593 :
11594 : cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
11595 : atomic_inc(&nohz.nr_cpus);
11596 :
11597 : /*
11598 : * Ensures that if nohz_idle_balance() fails to observe our
11599 : * @idle_cpus_mask store, it must observe the @has_blocked
11600 : * and @needs_update stores.
11601 : */
11602 : smp_mb__after_atomic();
11603 :
11604 : set_cpu_sd_state_idle(cpu);
11605 :
11606 : WRITE_ONCE(nohz.needs_update, 1);
11607 : out:
11608 : /*
11609 : * Each time a cpu enter idle, we assume that it has blocked load and
11610 : * enable the periodic update of the load of idle cpus
11611 : */
11612 : WRITE_ONCE(nohz.has_blocked, 1);
11613 : }
11614 :
11615 : static bool update_nohz_stats(struct rq *rq)
11616 : {
11617 : unsigned int cpu = rq->cpu;
11618 :
11619 : if (!rq->has_blocked_load)
11620 : return false;
11621 :
11622 : if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
11623 : return false;
11624 :
11625 : if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
11626 : return true;
11627 :
11628 : update_blocked_averages(cpu);
11629 :
11630 : return rq->has_blocked_load;
11631 : }
11632 :
11633 : /*
11634 : * Internal function that runs load balance for all idle cpus. The load balance
11635 : * can be a simple update of blocked load or a complete load balance with
11636 : * tasks movement depending of flags.
11637 : */
11638 : static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags)
11639 : {
11640 : /* Earliest time when we have to do rebalance again */
11641 : unsigned long now = jiffies;
11642 : unsigned long next_balance = now + 60*HZ;
11643 : bool has_blocked_load = false;
11644 : int update_next_balance = 0;
11645 : int this_cpu = this_rq->cpu;
11646 : int balance_cpu;
11647 : struct rq *rq;
11648 :
11649 : SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK);
11650 :
11651 : /*
11652 : * We assume there will be no idle load after this update and clear
11653 : * the has_blocked flag. If a cpu enters idle in the mean time, it will
11654 : * set the has_blocked flag and trigger another update of idle load.
11655 : * Because a cpu that becomes idle, is added to idle_cpus_mask before
11656 : * setting the flag, we are sure to not clear the state and not
11657 : * check the load of an idle cpu.
11658 : *
11659 : * Same applies to idle_cpus_mask vs needs_update.
11660 : */
11661 : if (flags & NOHZ_STATS_KICK)
11662 : WRITE_ONCE(nohz.has_blocked, 0);
11663 : if (flags & NOHZ_NEXT_KICK)
11664 : WRITE_ONCE(nohz.needs_update, 0);
11665 :
11666 : /*
11667 : * Ensures that if we miss the CPU, we must see the has_blocked
11668 : * store from nohz_balance_enter_idle().
11669 : */
11670 : smp_mb();
11671 :
11672 : /*
11673 : * Start with the next CPU after this_cpu so we will end with this_cpu and let a
11674 : * chance for other idle cpu to pull load.
11675 : */
11676 : for_each_cpu_wrap(balance_cpu, nohz.idle_cpus_mask, this_cpu+1) {
11677 : if (!idle_cpu(balance_cpu))
11678 : continue;
11679 :
11680 : /*
11681 : * If this CPU gets work to do, stop the load balancing
11682 : * work being done for other CPUs. Next load
11683 : * balancing owner will pick it up.
11684 : */
11685 : if (need_resched()) {
11686 : if (flags & NOHZ_STATS_KICK)
11687 : has_blocked_load = true;
11688 : if (flags & NOHZ_NEXT_KICK)
11689 : WRITE_ONCE(nohz.needs_update, 1);
11690 : goto abort;
11691 : }
11692 :
11693 : rq = cpu_rq(balance_cpu);
11694 :
11695 : if (flags & NOHZ_STATS_KICK)
11696 : has_blocked_load |= update_nohz_stats(rq);
11697 :
11698 : /*
11699 : * If time for next balance is due,
11700 : * do the balance.
11701 : */
11702 : if (time_after_eq(jiffies, rq->next_balance)) {
11703 : struct rq_flags rf;
11704 :
11705 : rq_lock_irqsave(rq, &rf);
11706 : update_rq_clock(rq);
11707 : rq_unlock_irqrestore(rq, &rf);
11708 :
11709 : if (flags & NOHZ_BALANCE_KICK)
11710 : rebalance_domains(rq, CPU_IDLE);
11711 : }
11712 :
11713 : if (time_after(next_balance, rq->next_balance)) {
11714 : next_balance = rq->next_balance;
11715 : update_next_balance = 1;
11716 : }
11717 : }
11718 :
11719 : /*
11720 : * next_balance will be updated only when there is a need.
11721 : * When the CPU is attached to null domain for ex, it will not be
11722 : * updated.
11723 : */
11724 : if (likely(update_next_balance))
11725 : nohz.next_balance = next_balance;
11726 :
11727 : if (flags & NOHZ_STATS_KICK)
11728 : WRITE_ONCE(nohz.next_blocked,
11729 : now + msecs_to_jiffies(LOAD_AVG_PERIOD));
11730 :
11731 : abort:
11732 : /* There is still blocked load, enable periodic update */
11733 : if (has_blocked_load)
11734 : WRITE_ONCE(nohz.has_blocked, 1);
11735 : }
11736 :
11737 : /*
11738 : * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
11739 : * rebalancing for all the cpus for whom scheduler ticks are stopped.
11740 : */
11741 : static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
11742 : {
11743 : unsigned int flags = this_rq->nohz_idle_balance;
11744 :
11745 : if (!flags)
11746 : return false;
11747 :
11748 : this_rq->nohz_idle_balance = 0;
11749 :
11750 : if (idle != CPU_IDLE)
11751 : return false;
11752 :
11753 : _nohz_idle_balance(this_rq, flags);
11754 :
11755 : return true;
11756 : }
11757 :
11758 : /*
11759 : * Check if we need to run the ILB for updating blocked load before entering
11760 : * idle state.
11761 : */
11762 : void nohz_run_idle_balance(int cpu)
11763 : {
11764 : unsigned int flags;
11765 :
11766 : flags = atomic_fetch_andnot(NOHZ_NEWILB_KICK, nohz_flags(cpu));
11767 :
11768 : /*
11769 : * Update the blocked load only if no SCHED_SOFTIRQ is about to happen
11770 : * (ie NOHZ_STATS_KICK set) and will do the same.
11771 : */
11772 : if ((flags == NOHZ_NEWILB_KICK) && !need_resched())
11773 : _nohz_idle_balance(cpu_rq(cpu), NOHZ_STATS_KICK);
11774 : }
11775 :
11776 : static void nohz_newidle_balance(struct rq *this_rq)
11777 : {
11778 : int this_cpu = this_rq->cpu;
11779 :
11780 : /*
11781 : * This CPU doesn't want to be disturbed by scheduler
11782 : * housekeeping
11783 : */
11784 : if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
11785 : return;
11786 :
11787 : /* Will wake up very soon. No time for doing anything else*/
11788 : if (this_rq->avg_idle < sysctl_sched_migration_cost)
11789 : return;
11790 :
11791 : /* Don't need to update blocked load of idle CPUs*/
11792 : if (!READ_ONCE(nohz.has_blocked) ||
11793 : time_before(jiffies, READ_ONCE(nohz.next_blocked)))
11794 : return;
11795 :
11796 : /*
11797 : * Set the need to trigger ILB in order to update blocked load
11798 : * before entering idle state.
11799 : */
11800 : atomic_or(NOHZ_NEWILB_KICK, nohz_flags(this_cpu));
11801 : }
11802 :
11803 : #else /* !CONFIG_NO_HZ_COMMON */
11804 : static inline void nohz_balancer_kick(struct rq *rq) { }
11805 :
11806 : static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
11807 : {
11808 : return false;
11809 : }
11810 :
11811 : static inline void nohz_newidle_balance(struct rq *this_rq) { }
11812 : #endif /* CONFIG_NO_HZ_COMMON */
11813 :
11814 : /*
11815 : * newidle_balance is called by schedule() if this_cpu is about to become
11816 : * idle. Attempts to pull tasks from other CPUs.
11817 : *
11818 : * Returns:
11819 : * < 0 - we released the lock and there are !fair tasks present
11820 : * 0 - failed, no new tasks
11821 : * > 0 - success, new (fair) tasks present
11822 : */
11823 : static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
11824 : {
11825 : unsigned long next_balance = jiffies + HZ;
11826 : int this_cpu = this_rq->cpu;
11827 : u64 t0, t1, curr_cost = 0;
11828 : struct sched_domain *sd;
11829 : int pulled_task = 0;
11830 :
11831 : update_misfit_status(NULL, this_rq);
11832 :
11833 : /*
11834 : * There is a task waiting to run. No need to search for one.
11835 : * Return 0; the task will be enqueued when switching to idle.
11836 : */
11837 : if (this_rq->ttwu_pending)
11838 : return 0;
11839 :
11840 : /*
11841 : * We must set idle_stamp _before_ calling idle_balance(), such that we
11842 : * measure the duration of idle_balance() as idle time.
11843 : */
11844 : this_rq->idle_stamp = rq_clock(this_rq);
11845 :
11846 : /*
11847 : * Do not pull tasks towards !active CPUs...
11848 : */
11849 : if (!cpu_active(this_cpu))
11850 : return 0;
11851 :
11852 : /*
11853 : * This is OK, because current is on_cpu, which avoids it being picked
11854 : * for load-balance and preemption/IRQs are still disabled avoiding
11855 : * further scheduler activity on it and we're being very careful to
11856 : * re-start the picking loop.
11857 : */
11858 : rq_unpin_lock(this_rq, rf);
11859 :
11860 : rcu_read_lock();
11861 : sd = rcu_dereference_check_sched_domain(this_rq->sd);
11862 :
11863 : if (!READ_ONCE(this_rq->rd->overload) ||
11864 : (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {
11865 :
11866 : if (sd)
11867 : update_next_balance(sd, &next_balance);
11868 : rcu_read_unlock();
11869 :
11870 : goto out;
11871 : }
11872 : rcu_read_unlock();
11873 :
11874 : raw_spin_rq_unlock(this_rq);
11875 :
11876 : t0 = sched_clock_cpu(this_cpu);
11877 : update_blocked_averages(this_cpu);
11878 :
11879 : rcu_read_lock();
11880 : for_each_domain(this_cpu, sd) {
11881 : int continue_balancing = 1;
11882 : u64 domain_cost;
11883 :
11884 : update_next_balance(sd, &next_balance);
11885 :
11886 : if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost)
11887 : break;
11888 :
11889 : if (sd->flags & SD_BALANCE_NEWIDLE) {
11890 :
11891 : pulled_task = load_balance(this_cpu, this_rq,
11892 : sd, CPU_NEWLY_IDLE,
11893 : &continue_balancing);
11894 :
11895 : t1 = sched_clock_cpu(this_cpu);
11896 : domain_cost = t1 - t0;
11897 : update_newidle_cost(sd, domain_cost);
11898 :
11899 : curr_cost += domain_cost;
11900 : t0 = t1;
11901 : }
11902 :
11903 : /*
11904 : * Stop searching for tasks to pull if there are
11905 : * now runnable tasks on this rq.
11906 : */
11907 : if (pulled_task || this_rq->nr_running > 0 ||
11908 : this_rq->ttwu_pending)
11909 : break;
11910 : }
11911 : rcu_read_unlock();
11912 :
11913 : raw_spin_rq_lock(this_rq);
11914 :
11915 : if (curr_cost > this_rq->max_idle_balance_cost)
11916 : this_rq->max_idle_balance_cost = curr_cost;
11917 :
11918 : /*
11919 : * While browsing the domains, we released the rq lock, a task could
11920 : * have been enqueued in the meantime. Since we're not going idle,
11921 : * pretend we pulled a task.
11922 : */
11923 : if (this_rq->cfs.h_nr_running && !pulled_task)
11924 : pulled_task = 1;
11925 :
11926 : /* Is there a task of a high priority class? */
11927 : if (this_rq->nr_running != this_rq->cfs.h_nr_running)
11928 : pulled_task = -1;
11929 :
11930 : out:
11931 : /* Move the next balance forward */
11932 : if (time_after(this_rq->next_balance, next_balance))
11933 : this_rq->next_balance = next_balance;
11934 :
11935 : if (pulled_task)
11936 : this_rq->idle_stamp = 0;
11937 : else
11938 : nohz_newidle_balance(this_rq);
11939 :
11940 : rq_repin_lock(this_rq, rf);
11941 :
11942 : return pulled_task;
11943 : }
11944 :
11945 : /*
11946 : * run_rebalance_domains is triggered when needed from the scheduler tick.
11947 : * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
11948 : */
11949 : static __latent_entropy void run_rebalance_domains(struct softirq_action *h)
11950 : {
11951 : struct rq *this_rq = this_rq();
11952 : enum cpu_idle_type idle = this_rq->idle_balance ?
11953 : CPU_IDLE : CPU_NOT_IDLE;
11954 :
11955 : /*
11956 : * If this CPU has a pending nohz_balance_kick, then do the
11957 : * balancing on behalf of the other idle CPUs whose ticks are
11958 : * stopped. Do nohz_idle_balance *before* rebalance_domains to
11959 : * give the idle CPUs a chance to load balance. Else we may
11960 : * load balance only within the local sched_domain hierarchy
11961 : * and abort nohz_idle_balance altogether if we pull some load.
11962 : */
11963 : if (nohz_idle_balance(this_rq, idle))
11964 : return;
11965 :
11966 : /* normal load balance */
11967 : update_blocked_averages(this_rq->cpu);
11968 : rebalance_domains(this_rq, idle);
11969 : }
11970 :
11971 : /*
11972 : * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
11973 : */
11974 : void trigger_load_balance(struct rq *rq)
11975 : {
11976 : /*
11977 : * Don't need to rebalance while attached to NULL domain or
11978 : * runqueue CPU is not active
11979 : */
11980 : if (unlikely(on_null_domain(rq) || !cpu_active(cpu_of(rq))))
11981 : return;
11982 :
11983 : if (time_after_eq(jiffies, rq->next_balance))
11984 : raise_softirq(SCHED_SOFTIRQ);
11985 :
11986 : nohz_balancer_kick(rq);
11987 : }
11988 :
11989 : static void rq_online_fair(struct rq *rq)
11990 : {
11991 : update_sysctl();
11992 :
11993 : update_runtime_enabled(rq);
11994 : }
11995 :
11996 : static void rq_offline_fair(struct rq *rq)
11997 : {
11998 : update_sysctl();
11999 :
12000 : /* Ensure any throttled groups are reachable by pick_next_task */
12001 : unthrottle_offline_cfs_rqs(rq);
12002 : }
12003 :
12004 : #endif /* CONFIG_SMP */
12005 :
12006 : #ifdef CONFIG_SCHED_CORE
12007 : static inline bool
12008 : __entity_slice_used(struct sched_entity *se, int min_nr_tasks)
12009 : {
12010 : u64 slice = sched_slice(cfs_rq_of(se), se);
12011 : u64 rtime = se->sum_exec_runtime - se->prev_sum_exec_runtime;
12012 :
12013 : return (rtime * min_nr_tasks > slice);
12014 : }
12015 :
12016 : #define MIN_NR_TASKS_DURING_FORCEIDLE 2
12017 : static inline void task_tick_core(struct rq *rq, struct task_struct *curr)
12018 : {
12019 : if (!sched_core_enabled(rq))
12020 : return;
12021 :
12022 : /*
12023 : * If runqueue has only one task which used up its slice and
12024 : * if the sibling is forced idle, then trigger schedule to
12025 : * give forced idle task a chance.
12026 : *
12027 : * sched_slice() considers only this active rq and it gets the
12028 : * whole slice. But during force idle, we have siblings acting
12029 : * like a single runqueue and hence we need to consider runnable
12030 : * tasks on this CPU and the forced idle CPU. Ideally, we should
12031 : * go through the forced idle rq, but that would be a perf hit.
12032 : * We can assume that the forced idle CPU has at least
12033 : * MIN_NR_TASKS_DURING_FORCEIDLE - 1 tasks and use that to check
12034 : * if we need to give up the CPU.
12035 : */
12036 : if (rq->core->core_forceidle_count && rq->cfs.nr_running == 1 &&
12037 : __entity_slice_used(&curr->se, MIN_NR_TASKS_DURING_FORCEIDLE))
12038 : resched_curr(rq);
12039 : }
12040 :
12041 : /*
12042 : * se_fi_update - Update the cfs_rq->min_vruntime_fi in a CFS hierarchy if needed.
12043 : */
12044 : static void se_fi_update(const struct sched_entity *se, unsigned int fi_seq,
12045 : bool forceidle)
12046 : {
12047 : for_each_sched_entity(se) {
12048 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12049 :
12050 : if (forceidle) {
12051 : if (cfs_rq->forceidle_seq == fi_seq)
12052 : break;
12053 : cfs_rq->forceidle_seq = fi_seq;
12054 : }
12055 :
12056 : cfs_rq->min_vruntime_fi = cfs_rq->min_vruntime;
12057 : }
12058 : }
12059 :
12060 : void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi)
12061 : {
12062 : struct sched_entity *se = &p->se;
12063 :
12064 : if (p->sched_class != &fair_sched_class)
12065 : return;
12066 :
12067 : se_fi_update(se, rq->core->core_forceidle_seq, in_fi);
12068 : }
12069 :
12070 : bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
12071 : bool in_fi)
12072 : {
12073 : struct rq *rq = task_rq(a);
12074 : const struct sched_entity *sea = &a->se;
12075 : const struct sched_entity *seb = &b->se;
12076 : struct cfs_rq *cfs_rqa;
12077 : struct cfs_rq *cfs_rqb;
12078 : s64 delta;
12079 :
12080 : SCHED_WARN_ON(task_rq(b)->core != rq->core);
12081 :
12082 : #ifdef CONFIG_FAIR_GROUP_SCHED
12083 : /*
12084 : * Find an se in the hierarchy for tasks a and b, such that the se's
12085 : * are immediate siblings.
12086 : */
12087 : while (sea->cfs_rq->tg != seb->cfs_rq->tg) {
12088 : int sea_depth = sea->depth;
12089 : int seb_depth = seb->depth;
12090 :
12091 : if (sea_depth >= seb_depth)
12092 : sea = parent_entity(sea);
12093 : if (sea_depth <= seb_depth)
12094 : seb = parent_entity(seb);
12095 : }
12096 :
12097 : se_fi_update(sea, rq->core->core_forceidle_seq, in_fi);
12098 : se_fi_update(seb, rq->core->core_forceidle_seq, in_fi);
12099 :
12100 : cfs_rqa = sea->cfs_rq;
12101 : cfs_rqb = seb->cfs_rq;
12102 : #else
12103 : cfs_rqa = &task_rq(a)->cfs;
12104 : cfs_rqb = &task_rq(b)->cfs;
12105 : #endif
12106 :
12107 : /*
12108 : * Find delta after normalizing se's vruntime with its cfs_rq's
12109 : * min_vruntime_fi, which would have been updated in prior calls
12110 : * to se_fi_update().
12111 : */
12112 : delta = (s64)(sea->vruntime - seb->vruntime) +
12113 : (s64)(cfs_rqb->min_vruntime_fi - cfs_rqa->min_vruntime_fi);
12114 :
12115 : return delta > 0;
12116 : }
12117 :
12118 : static int task_is_throttled_fair(struct task_struct *p, int cpu)
12119 : {
12120 : struct cfs_rq *cfs_rq;
12121 :
12122 : #ifdef CONFIG_FAIR_GROUP_SCHED
12123 : cfs_rq = task_group(p)->cfs_rq[cpu];
12124 : #else
12125 : cfs_rq = &cpu_rq(cpu)->cfs;
12126 : #endif
12127 : return throttled_hierarchy(cfs_rq);
12128 : }
12129 : #else
12130 : static inline void task_tick_core(struct rq *rq, struct task_struct *curr) {}
12131 : #endif
12132 :
12133 : /*
12134 : * scheduler tick hitting a task of our scheduling class.
12135 : *
12136 : * NOTE: This function can be called remotely by the tick offload that
12137 : * goes along full dynticks. Therefore no local assumption can be made
12138 : * and everything must be accessed through the @rq and @curr passed in
12139 : * parameters.
12140 : */
12141 1 : static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
12142 : {
12143 : struct cfs_rq *cfs_rq;
12144 1 : struct sched_entity *se = &curr->se;
12145 :
12146 2 : for_each_sched_entity(se) {
12147 2 : cfs_rq = cfs_rq_of(se);
12148 1 : entity_tick(cfs_rq, se, queued);
12149 : }
12150 :
12151 1 : if (static_branch_unlikely(&sched_numa_balancing))
12152 : task_tick_numa(rq, curr);
12153 :
12154 1 : update_misfit_status(curr, rq);
12155 1 : update_overutilized_status(task_rq(curr));
12156 :
12157 1 : task_tick_core(rq, curr);
12158 1 : }
12159 :
12160 : /*
12161 : * called on fork with the child task as argument from the parent's context
12162 : * - child not yet on the tasklist
12163 : * - preemption disabled
12164 : */
12165 175 : static void task_fork_fair(struct task_struct *p)
12166 : {
12167 : struct cfs_rq *cfs_rq;
12168 175 : struct sched_entity *se = &p->se, *curr;
12169 175 : struct rq *rq = this_rq();
12170 : struct rq_flags rf;
12171 :
12172 350 : rq_lock(rq, &rf);
12173 175 : update_rq_clock(rq);
12174 :
12175 350 : cfs_rq = task_cfs_rq(current);
12176 175 : curr = cfs_rq->curr;
12177 175 : if (curr) {
12178 173 : update_curr(cfs_rq);
12179 173 : se->vruntime = curr->vruntime;
12180 : }
12181 175 : place_entity(cfs_rq, se, 1);
12182 :
12183 175 : if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
12184 : /*
12185 : * Upon rescheduling, sched_class::put_prev_task() will place
12186 : * 'current' within the tree based on its new key value.
12187 : */
12188 0 : swap(curr->vruntime, se->vruntime);
12189 0 : resched_curr(rq);
12190 : }
12191 :
12192 175 : se->vruntime -= cfs_rq->min_vruntime;
12193 350 : rq_unlock(rq, &rf);
12194 175 : }
12195 :
12196 : /*
12197 : * Priority of the task has changed. Check to see if we preempt
12198 : * the current task.
12199 : */
12200 : static void
12201 5 : prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
12202 : {
12203 5 : if (!task_on_rq_queued(p))
12204 : return;
12205 :
12206 4 : if (rq->cfs.nr_running == 1)
12207 : return;
12208 :
12209 : /*
12210 : * Reschedule if we are currently running on this runqueue and
12211 : * our priority decreased, or if we are not currently running on
12212 : * this runqueue and our priority is higher than the current's
12213 : */
12214 4 : if (task_current(rq, p)) {
12215 4 : if (p->prio > oldprio)
12216 0 : resched_curr(rq);
12217 : } else
12218 0 : check_preempt_curr(rq, p, 0);
12219 : }
12220 :
12221 : static inline bool vruntime_normalized(struct task_struct *p)
12222 : {
12223 0 : struct sched_entity *se = &p->se;
12224 :
12225 : /*
12226 : * In both the TASK_ON_RQ_QUEUED and TASK_ON_RQ_MIGRATING cases,
12227 : * the dequeue_entity(.flags=0) will already have normalized the
12228 : * vruntime.
12229 : */
12230 0 : if (p->on_rq)
12231 : return true;
12232 :
12233 : /*
12234 : * When !on_rq, vruntime of the task has usually NOT been normalized.
12235 : * But there are some cases where it has already been normalized:
12236 : *
12237 : * - A forked child which is waiting for being woken up by
12238 : * wake_up_new_task().
12239 : * - A task which has been woken up by try_to_wake_up() and
12240 : * waiting for actually being woken up by sched_ttwu_pending().
12241 : */
12242 0 : if (!se->sum_exec_runtime ||
12243 0 : (READ_ONCE(p->__state) == TASK_WAKING && p->sched_remote_wakeup))
12244 : return true;
12245 :
12246 : return false;
12247 : }
12248 :
12249 : #ifdef CONFIG_FAIR_GROUP_SCHED
12250 : /*
12251 : * Propagate the changes of the sched_entity across the tg tree to make it
12252 : * visible to the root
12253 : */
12254 : static void propagate_entity_cfs_rq(struct sched_entity *se)
12255 : {
12256 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12257 :
12258 : if (cfs_rq_throttled(cfs_rq))
12259 : return;
12260 :
12261 : if (!throttled_hierarchy(cfs_rq))
12262 : list_add_leaf_cfs_rq(cfs_rq);
12263 :
12264 : /* Start to propagate at parent */
12265 : se = se->parent;
12266 :
12267 : for_each_sched_entity(se) {
12268 : cfs_rq = cfs_rq_of(se);
12269 :
12270 : update_load_avg(cfs_rq, se, UPDATE_TG);
12271 :
12272 : if (cfs_rq_throttled(cfs_rq))
12273 : break;
12274 :
12275 : if (!throttled_hierarchy(cfs_rq))
12276 : list_add_leaf_cfs_rq(cfs_rq);
12277 : }
12278 : }
12279 : #else
12280 : static void propagate_entity_cfs_rq(struct sched_entity *se) { }
12281 : #endif
12282 :
12283 : static void detach_entity_cfs_rq(struct sched_entity *se)
12284 : {
12285 0 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12286 :
12287 : #ifdef CONFIG_SMP
12288 : /*
12289 : * In case the task sched_avg hasn't been attached:
12290 : * - A forked task which hasn't been woken up by wake_up_new_task().
12291 : * - A task which has been woken up by try_to_wake_up() but is
12292 : * waiting for actually being woken up by sched_ttwu_pending().
12293 : */
12294 : if (!se->avg.last_update_time)
12295 : return;
12296 : #endif
12297 :
12298 : /* Catch up with the cfs_rq and remove our load when we leave */
12299 0 : update_load_avg(cfs_rq, se, 0);
12300 0 : detach_entity_load_avg(cfs_rq, se);
12301 : update_tg_load_avg(cfs_rq);
12302 0 : propagate_entity_cfs_rq(se);
12303 : }
12304 :
12305 : static void attach_entity_cfs_rq(struct sched_entity *se)
12306 : {
12307 0 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12308 :
12309 : /* Synchronize entity with its cfs_rq */
12310 0 : update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
12311 0 : attach_entity_load_avg(cfs_rq, se);
12312 : update_tg_load_avg(cfs_rq);
12313 0 : propagate_entity_cfs_rq(se);
12314 : }
12315 :
12316 0 : static void detach_task_cfs_rq(struct task_struct *p)
12317 : {
12318 0 : struct sched_entity *se = &p->se;
12319 0 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12320 :
12321 0 : if (!vruntime_normalized(p)) {
12322 : /*
12323 : * Fix up our vruntime so that the current sleep doesn't
12324 : * cause 'unlimited' sleep bonus.
12325 : */
12326 0 : place_entity(cfs_rq, se, 0);
12327 0 : se->vruntime -= cfs_rq->min_vruntime;
12328 : }
12329 :
12330 0 : detach_entity_cfs_rq(se);
12331 0 : }
12332 :
12333 : static void attach_task_cfs_rq(struct task_struct *p)
12334 : {
12335 0 : struct sched_entity *se = &p->se;
12336 0 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12337 :
12338 0 : attach_entity_cfs_rq(se);
12339 :
12340 0 : if (!vruntime_normalized(p))
12341 0 : se->vruntime += cfs_rq->min_vruntime;
12342 : }
12343 :
12344 0 : static void switched_from_fair(struct rq *rq, struct task_struct *p)
12345 : {
12346 0 : detach_task_cfs_rq(p);
12347 0 : }
12348 :
12349 0 : static void switched_to_fair(struct rq *rq, struct task_struct *p)
12350 : {
12351 0 : attach_task_cfs_rq(p);
12352 :
12353 0 : if (task_on_rq_queued(p)) {
12354 : /*
12355 : * We were most likely switched from sched_rt, so
12356 : * kick off the schedule if running, otherwise just see
12357 : * if we can still preempt the current task.
12358 : */
12359 0 : if (task_current(rq, p))
12360 0 : resched_curr(rq);
12361 : else
12362 0 : check_preempt_curr(rq, p, 0);
12363 : }
12364 0 : }
12365 :
12366 : /* Account for a task changing its policy or group.
12367 : *
12368 : * This routine is mostly called to set cfs_rq->curr field when a task
12369 : * migrates between groups/classes.
12370 : */
12371 4 : static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
12372 : {
12373 4 : struct sched_entity *se = &p->se;
12374 :
12375 : #ifdef CONFIG_SMP
12376 : if (task_on_rq_queued(p)) {
12377 : /*
12378 : * Move the next running task to the front of the list, so our
12379 : * cfs_tasks list becomes MRU one.
12380 : */
12381 : list_move(&se->group_node, &rq->cfs_tasks);
12382 : }
12383 : #endif
12384 :
12385 8 : for_each_sched_entity(se) {
12386 8 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12387 :
12388 4 : set_next_entity(cfs_rq, se);
12389 : /* ensure bandwidth has been allocated on our new cfs_rq */
12390 4 : account_cfs_rq_runtime(cfs_rq, 0);
12391 : }
12392 4 : }
12393 :
12394 1 : void init_cfs_rq(struct cfs_rq *cfs_rq)
12395 : {
12396 1 : cfs_rq->tasks_timeline = RB_ROOT_CACHED;
12397 1 : u64_u32_store(cfs_rq->min_vruntime, (u64)(-(1LL << 20)));
12398 : #ifdef CONFIG_SMP
12399 : raw_spin_lock_init(&cfs_rq->removed.lock);
12400 : #endif
12401 1 : }
12402 :
12403 : #ifdef CONFIG_FAIR_GROUP_SCHED
12404 : static void task_change_group_fair(struct task_struct *p)
12405 : {
12406 : /*
12407 : * We couldn't detach or attach a forked task which
12408 : * hasn't been woken up by wake_up_new_task().
12409 : */
12410 : if (READ_ONCE(p->__state) == TASK_NEW)
12411 : return;
12412 :
12413 : detach_task_cfs_rq(p);
12414 :
12415 : #ifdef CONFIG_SMP
12416 : /* Tell se's cfs_rq has been changed -- migrated */
12417 : p->se.avg.last_update_time = 0;
12418 : #endif
12419 : set_task_rq(p, task_cpu(p));
12420 : attach_task_cfs_rq(p);
12421 : }
12422 :
12423 : void free_fair_sched_group(struct task_group *tg)
12424 : {
12425 : int i;
12426 :
12427 : for_each_possible_cpu(i) {
12428 : if (tg->cfs_rq)
12429 : kfree(tg->cfs_rq[i]);
12430 : if (tg->se)
12431 : kfree(tg->se[i]);
12432 : }
12433 :
12434 : kfree(tg->cfs_rq);
12435 : kfree(tg->se);
12436 : }
12437 :
12438 : int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
12439 : {
12440 : struct sched_entity *se;
12441 : struct cfs_rq *cfs_rq;
12442 : int i;
12443 :
12444 : tg->cfs_rq = kcalloc(nr_cpu_ids, sizeof(cfs_rq), GFP_KERNEL);
12445 : if (!tg->cfs_rq)
12446 : goto err;
12447 : tg->se = kcalloc(nr_cpu_ids, sizeof(se), GFP_KERNEL);
12448 : if (!tg->se)
12449 : goto err;
12450 :
12451 : tg->shares = NICE_0_LOAD;
12452 :
12453 : init_cfs_bandwidth(tg_cfs_bandwidth(tg));
12454 :
12455 : for_each_possible_cpu(i) {
12456 : cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
12457 : GFP_KERNEL, cpu_to_node(i));
12458 : if (!cfs_rq)
12459 : goto err;
12460 :
12461 : se = kzalloc_node(sizeof(struct sched_entity_stats),
12462 : GFP_KERNEL, cpu_to_node(i));
12463 : if (!se)
12464 : goto err_free_rq;
12465 :
12466 : init_cfs_rq(cfs_rq);
12467 : init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
12468 : init_entity_runnable_average(se);
12469 : }
12470 :
12471 : return 1;
12472 :
12473 : err_free_rq:
12474 : kfree(cfs_rq);
12475 : err:
12476 : return 0;
12477 : }
12478 :
12479 : void online_fair_sched_group(struct task_group *tg)
12480 : {
12481 : struct sched_entity *se;
12482 : struct rq_flags rf;
12483 : struct rq *rq;
12484 : int i;
12485 :
12486 : for_each_possible_cpu(i) {
12487 : rq = cpu_rq(i);
12488 : se = tg->se[i];
12489 : rq_lock_irq(rq, &rf);
12490 : update_rq_clock(rq);
12491 : attach_entity_cfs_rq(se);
12492 : sync_throttle(tg, i);
12493 : rq_unlock_irq(rq, &rf);
12494 : }
12495 : }
12496 :
12497 : void unregister_fair_sched_group(struct task_group *tg)
12498 : {
12499 : unsigned long flags;
12500 : struct rq *rq;
12501 : int cpu;
12502 :
12503 : destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
12504 :
12505 : for_each_possible_cpu(cpu) {
12506 : if (tg->se[cpu])
12507 : remove_entity_load_avg(tg->se[cpu]);
12508 :
12509 : /*
12510 : * Only empty task groups can be destroyed; so we can speculatively
12511 : * check on_list without danger of it being re-added.
12512 : */
12513 : if (!tg->cfs_rq[cpu]->on_list)
12514 : continue;
12515 :
12516 : rq = cpu_rq(cpu);
12517 :
12518 : raw_spin_rq_lock_irqsave(rq, flags);
12519 : list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
12520 : raw_spin_rq_unlock_irqrestore(rq, flags);
12521 : }
12522 : }
12523 :
12524 : void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
12525 : struct sched_entity *se, int cpu,
12526 : struct sched_entity *parent)
12527 : {
12528 : struct rq *rq = cpu_rq(cpu);
12529 :
12530 : cfs_rq->tg = tg;
12531 : cfs_rq->rq = rq;
12532 : init_cfs_rq_runtime(cfs_rq);
12533 :
12534 : tg->cfs_rq[cpu] = cfs_rq;
12535 : tg->se[cpu] = se;
12536 :
12537 : /* se could be NULL for root_task_group */
12538 : if (!se)
12539 : return;
12540 :
12541 : if (!parent) {
12542 : se->cfs_rq = &rq->cfs;
12543 : se->depth = 0;
12544 : } else {
12545 : se->cfs_rq = parent->my_q;
12546 : se->depth = parent->depth + 1;
12547 : }
12548 :
12549 : se->my_q = cfs_rq;
12550 : /* guarantee group entities always have weight */
12551 : update_load_set(&se->load, NICE_0_LOAD);
12552 : se->parent = parent;
12553 : }
12554 :
12555 : static DEFINE_MUTEX(shares_mutex);
12556 :
12557 : static int __sched_group_set_shares(struct task_group *tg, unsigned long shares)
12558 : {
12559 : int i;
12560 :
12561 : lockdep_assert_held(&shares_mutex);
12562 :
12563 : /*
12564 : * We can't change the weight of the root cgroup.
12565 : */
12566 : if (!tg->se[0])
12567 : return -EINVAL;
12568 :
12569 : shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
12570 :
12571 : if (tg->shares == shares)
12572 : return 0;
12573 :
12574 : tg->shares = shares;
12575 : for_each_possible_cpu(i) {
12576 : struct rq *rq = cpu_rq(i);
12577 : struct sched_entity *se = tg->se[i];
12578 : struct rq_flags rf;
12579 :
12580 : /* Propagate contribution to hierarchy */
12581 : rq_lock_irqsave(rq, &rf);
12582 : update_rq_clock(rq);
12583 : for_each_sched_entity(se) {
12584 : update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
12585 : update_cfs_group(se);
12586 : }
12587 : rq_unlock_irqrestore(rq, &rf);
12588 : }
12589 :
12590 : return 0;
12591 : }
12592 :
12593 : int sched_group_set_shares(struct task_group *tg, unsigned long shares)
12594 : {
12595 : int ret;
12596 :
12597 : mutex_lock(&shares_mutex);
12598 : if (tg_is_idle(tg))
12599 : ret = -EINVAL;
12600 : else
12601 : ret = __sched_group_set_shares(tg, shares);
12602 : mutex_unlock(&shares_mutex);
12603 :
12604 : return ret;
12605 : }
12606 :
12607 : int sched_group_set_idle(struct task_group *tg, long idle)
12608 : {
12609 : int i;
12610 :
12611 : if (tg == &root_task_group)
12612 : return -EINVAL;
12613 :
12614 : if (idle < 0 || idle > 1)
12615 : return -EINVAL;
12616 :
12617 : mutex_lock(&shares_mutex);
12618 :
12619 : if (tg->idle == idle) {
12620 : mutex_unlock(&shares_mutex);
12621 : return 0;
12622 : }
12623 :
12624 : tg->idle = idle;
12625 :
12626 : for_each_possible_cpu(i) {
12627 : struct rq *rq = cpu_rq(i);
12628 : struct sched_entity *se = tg->se[i];
12629 : struct cfs_rq *parent_cfs_rq, *grp_cfs_rq = tg->cfs_rq[i];
12630 : bool was_idle = cfs_rq_is_idle(grp_cfs_rq);
12631 : long idle_task_delta;
12632 : struct rq_flags rf;
12633 :
12634 : rq_lock_irqsave(rq, &rf);
12635 :
12636 : grp_cfs_rq->idle = idle;
12637 : if (WARN_ON_ONCE(was_idle == cfs_rq_is_idle(grp_cfs_rq)))
12638 : goto next_cpu;
12639 :
12640 : if (se->on_rq) {
12641 : parent_cfs_rq = cfs_rq_of(se);
12642 : if (cfs_rq_is_idle(grp_cfs_rq))
12643 : parent_cfs_rq->idle_nr_running++;
12644 : else
12645 : parent_cfs_rq->idle_nr_running--;
12646 : }
12647 :
12648 : idle_task_delta = grp_cfs_rq->h_nr_running -
12649 : grp_cfs_rq->idle_h_nr_running;
12650 : if (!cfs_rq_is_idle(grp_cfs_rq))
12651 : idle_task_delta *= -1;
12652 :
12653 : for_each_sched_entity(se) {
12654 : struct cfs_rq *cfs_rq = cfs_rq_of(se);
12655 :
12656 : if (!se->on_rq)
12657 : break;
12658 :
12659 : cfs_rq->idle_h_nr_running += idle_task_delta;
12660 :
12661 : /* Already accounted at parent level and above. */
12662 : if (cfs_rq_is_idle(cfs_rq))
12663 : break;
12664 : }
12665 :
12666 : next_cpu:
12667 : rq_unlock_irqrestore(rq, &rf);
12668 : }
12669 :
12670 : /* Idle groups have minimum weight. */
12671 : if (tg_is_idle(tg))
12672 : __sched_group_set_shares(tg, scale_load(WEIGHT_IDLEPRIO));
12673 : else
12674 : __sched_group_set_shares(tg, NICE_0_LOAD);
12675 :
12676 : mutex_unlock(&shares_mutex);
12677 : return 0;
12678 : }
12679 :
12680 : #else /* CONFIG_FAIR_GROUP_SCHED */
12681 :
12682 0 : void free_fair_sched_group(struct task_group *tg) { }
12683 :
12684 0 : int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
12685 : {
12686 0 : return 1;
12687 : }
12688 :
12689 0 : void online_fair_sched_group(struct task_group *tg) { }
12690 :
12691 0 : void unregister_fair_sched_group(struct task_group *tg) { }
12692 :
12693 : #endif /* CONFIG_FAIR_GROUP_SCHED */
12694 :
12695 :
12696 0 : static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
12697 : {
12698 0 : struct sched_entity *se = &task->se;
12699 0 : unsigned int rr_interval = 0;
12700 :
12701 : /*
12702 : * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
12703 : * idle runqueue:
12704 : */
12705 0 : if (rq->cfs.load.weight)
12706 0 : rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));
12707 :
12708 0 : return rr_interval;
12709 : }
12710 :
12711 : /*
12712 : * All the scheduling class methods:
12713 : */
12714 : DEFINE_SCHED_CLASS(fair) = {
12715 :
12716 : .enqueue_task = enqueue_task_fair,
12717 : .dequeue_task = dequeue_task_fair,
12718 : .yield_task = yield_task_fair,
12719 : .yield_to_task = yield_to_task_fair,
12720 :
12721 : .check_preempt_curr = check_preempt_wakeup,
12722 :
12723 : .pick_next_task = __pick_next_task_fair,
12724 : .put_prev_task = put_prev_task_fair,
12725 : .set_next_task = set_next_task_fair,
12726 :
12727 : #ifdef CONFIG_SMP
12728 : .balance = balance_fair,
12729 : .pick_task = pick_task_fair,
12730 : .select_task_rq = select_task_rq_fair,
12731 : .migrate_task_rq = migrate_task_rq_fair,
12732 :
12733 : .rq_online = rq_online_fair,
12734 : .rq_offline = rq_offline_fair,
12735 :
12736 : .task_dead = task_dead_fair,
12737 : .set_cpus_allowed = set_cpus_allowed_common,
12738 : #endif
12739 :
12740 : .task_tick = task_tick_fair,
12741 : .task_fork = task_fork_fair,
12742 :
12743 : .prio_changed = prio_changed_fair,
12744 : .switched_from = switched_from_fair,
12745 : .switched_to = switched_to_fair,
12746 :
12747 : .get_rr_interval = get_rr_interval_fair,
12748 :
12749 : .update_curr = update_curr_fair,
12750 :
12751 : #ifdef CONFIG_FAIR_GROUP_SCHED
12752 : .task_change_group = task_change_group_fair,
12753 : #endif
12754 :
12755 : #ifdef CONFIG_SCHED_CORE
12756 : .task_is_throttled = task_is_throttled_fair,
12757 : #endif
12758 :
12759 : #ifdef CONFIG_UCLAMP_TASK
12760 : .uclamp_enabled = 1,
12761 : #endif
12762 : };
12763 :
12764 : #ifdef CONFIG_SCHED_DEBUG
12765 : void print_cfs_stats(struct seq_file *m, int cpu)
12766 : {
12767 : struct cfs_rq *cfs_rq, *pos;
12768 :
12769 : rcu_read_lock();
12770 : for_each_leaf_cfs_rq_safe(cpu_rq(cpu), cfs_rq, pos)
12771 : print_cfs_rq(m, cpu, cfs_rq);
12772 : rcu_read_unlock();
12773 : }
12774 :
12775 : #ifdef CONFIG_NUMA_BALANCING
12776 : void show_numa_stats(struct task_struct *p, struct seq_file *m)
12777 : {
12778 : int node;
12779 : unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0;
12780 : struct numa_group *ng;
12781 :
12782 : rcu_read_lock();
12783 : ng = rcu_dereference(p->numa_group);
12784 : for_each_online_node(node) {
12785 : if (p->numa_faults) {
12786 : tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)];
12787 : tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)];
12788 : }
12789 : if (ng) {
12790 : gsf = ng->faults[task_faults_idx(NUMA_MEM, node, 0)],
12791 : gpf = ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
12792 : }
12793 : print_numa_stats(m, node, tsf, tpf, gsf, gpf);
12794 : }
12795 : rcu_read_unlock();
12796 : }
12797 : #endif /* CONFIG_NUMA_BALANCING */
12798 : #endif /* CONFIG_SCHED_DEBUG */
12799 :
12800 1 : __init void init_sched_fair_class(void)
12801 : {
12802 : #ifdef CONFIG_SMP
12803 : int i;
12804 :
12805 : for_each_possible_cpu(i) {
12806 : zalloc_cpumask_var_node(&per_cpu(load_balance_mask, i), GFP_KERNEL, cpu_to_node(i));
12807 : zalloc_cpumask_var_node(&per_cpu(select_rq_mask, i), GFP_KERNEL, cpu_to_node(i));
12808 :
12809 : #ifdef CONFIG_CFS_BANDWIDTH
12810 : INIT_CSD(&cpu_rq(i)->cfsb_csd, __cfsb_csd_unthrottle, cpu_rq(i));
12811 : INIT_LIST_HEAD(&cpu_rq(i)->cfsb_csd_list);
12812 : #endif
12813 : }
12814 :
12815 : open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
12816 :
12817 : #ifdef CONFIG_NO_HZ_COMMON
12818 : nohz.next_balance = jiffies;
12819 : nohz.next_blocked = jiffies;
12820 : zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
12821 : #endif
12822 : #endif /* SMP */
12823 :
12824 1 : }
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