Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Deadline Scheduling Class (SCHED_DEADLINE)
4 : *
5 : * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
6 : *
7 : * Tasks that periodically executes their instances for less than their
8 : * runtime won't miss any of their deadlines.
9 : * Tasks that are not periodic or sporadic or that tries to execute more
10 : * than their reserved bandwidth will be slowed down (and may potentially
11 : * miss some of their deadlines), and won't affect any other task.
12 : *
13 : * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
14 : * Juri Lelli <juri.lelli@gmail.com>,
15 : * Michael Trimarchi <michael@amarulasolutions.com>,
16 : * Fabio Checconi <fchecconi@gmail.com>
17 : */
18 :
19 : #include <linux/cpuset.h>
20 :
21 : /*
22 : * Default limits for DL period; on the top end we guard against small util
23 : * tasks still getting ridiculously long effective runtimes, on the bottom end we
24 : * guard against timer DoS.
25 : */
26 : static unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */
27 : static unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */
28 : #ifdef CONFIG_SYSCTL
29 : static struct ctl_table sched_dl_sysctls[] = {
30 : {
31 : .procname = "sched_deadline_period_max_us",
32 : .data = &sysctl_sched_dl_period_max,
33 : .maxlen = sizeof(unsigned int),
34 : .mode = 0644,
35 : .proc_handler = proc_douintvec_minmax,
36 : .extra1 = (void *)&sysctl_sched_dl_period_min,
37 : },
38 : {
39 : .procname = "sched_deadline_period_min_us",
40 : .data = &sysctl_sched_dl_period_min,
41 : .maxlen = sizeof(unsigned int),
42 : .mode = 0644,
43 : .proc_handler = proc_douintvec_minmax,
44 : .extra2 = (void *)&sysctl_sched_dl_period_max,
45 : },
46 : {}
47 : };
48 :
49 1 : static int __init sched_dl_sysctl_init(void)
50 : {
51 1 : register_sysctl_init("kernel", sched_dl_sysctls);
52 1 : return 0;
53 : }
54 : late_initcall(sched_dl_sysctl_init);
55 : #endif
56 :
57 : static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
58 : {
59 0 : return container_of(dl_se, struct task_struct, dl);
60 : }
61 :
62 : static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
63 : {
64 0 : return container_of(dl_rq, struct rq, dl);
65 : }
66 :
67 : static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
68 : {
69 0 : struct task_struct *p = dl_task_of(dl_se);
70 0 : struct rq *rq = task_rq(p);
71 :
72 : return &rq->dl;
73 : }
74 :
75 : static inline int on_dl_rq(struct sched_dl_entity *dl_se)
76 : {
77 0 : return !RB_EMPTY_NODE(&dl_se->rb_node);
78 : }
79 :
80 : #ifdef CONFIG_RT_MUTEXES
81 : static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se)
82 : {
83 : return dl_se->pi_se;
84 : }
85 :
86 : static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
87 : {
88 0 : return pi_of(dl_se) != dl_se;
89 : }
90 : #else
91 : static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se)
92 : {
93 : return dl_se;
94 : }
95 :
96 : static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
97 : {
98 : return false;
99 : }
100 : #endif
101 :
102 : #ifdef CONFIG_SMP
103 : static inline struct dl_bw *dl_bw_of(int i)
104 : {
105 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
106 : "sched RCU must be held");
107 : return &cpu_rq(i)->rd->dl_bw;
108 : }
109 :
110 : static inline int dl_bw_cpus(int i)
111 : {
112 : struct root_domain *rd = cpu_rq(i)->rd;
113 : int cpus;
114 :
115 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
116 : "sched RCU must be held");
117 :
118 : if (cpumask_subset(rd->span, cpu_active_mask))
119 : return cpumask_weight(rd->span);
120 :
121 : cpus = 0;
122 :
123 : for_each_cpu_and(i, rd->span, cpu_active_mask)
124 : cpus++;
125 :
126 : return cpus;
127 : }
128 :
129 : static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)
130 : {
131 : unsigned long cap = 0;
132 : int i;
133 :
134 : for_each_cpu_and(i, mask, cpu_active_mask)
135 : cap += capacity_orig_of(i);
136 :
137 : return cap;
138 : }
139 :
140 : /*
141 : * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity
142 : * of the CPU the task is running on rather rd's \Sum CPU capacity.
143 : */
144 : static inline unsigned long dl_bw_capacity(int i)
145 : {
146 : if (!sched_asym_cpucap_active() &&
147 : capacity_orig_of(i) == SCHED_CAPACITY_SCALE) {
148 : return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
149 : } else {
150 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
151 : "sched RCU must be held");
152 :
153 : return __dl_bw_capacity(cpu_rq(i)->rd->span);
154 : }
155 : }
156 :
157 : static inline bool dl_bw_visited(int cpu, u64 gen)
158 : {
159 : struct root_domain *rd = cpu_rq(cpu)->rd;
160 :
161 : if (rd->visit_gen == gen)
162 : return true;
163 :
164 : rd->visit_gen = gen;
165 : return false;
166 : }
167 :
168 : static inline
169 : void __dl_update(struct dl_bw *dl_b, s64 bw)
170 : {
171 : struct root_domain *rd = container_of(dl_b, struct root_domain, dl_bw);
172 : int i;
173 :
174 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
175 : "sched RCU must be held");
176 : for_each_cpu_and(i, rd->span, cpu_active_mask) {
177 : struct rq *rq = cpu_rq(i);
178 :
179 : rq->dl.extra_bw += bw;
180 : }
181 : }
182 : #else
183 : static inline struct dl_bw *dl_bw_of(int i)
184 : {
185 0 : return &cpu_rq(i)->dl.dl_bw;
186 : }
187 :
188 : static inline int dl_bw_cpus(int i)
189 : {
190 : return 1;
191 : }
192 :
193 : static inline unsigned long dl_bw_capacity(int i)
194 : {
195 : return SCHED_CAPACITY_SCALE;
196 : }
197 :
198 : static inline bool dl_bw_visited(int cpu, u64 gen)
199 : {
200 : return false;
201 : }
202 :
203 : static inline
204 : void __dl_update(struct dl_bw *dl_b, s64 bw)
205 : {
206 0 : struct dl_rq *dl = container_of(dl_b, struct dl_rq, dl_bw);
207 :
208 0 : dl->extra_bw += bw;
209 : }
210 : #endif
211 :
212 : static inline
213 : void __dl_sub(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
214 : {
215 0 : dl_b->total_bw -= tsk_bw;
216 0 : __dl_update(dl_b, (s32)tsk_bw / cpus);
217 : }
218 :
219 : static inline
220 : void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
221 : {
222 0 : dl_b->total_bw += tsk_bw;
223 0 : __dl_update(dl_b, -((s32)tsk_bw / cpus));
224 : }
225 :
226 : static inline bool
227 : __dl_overflow(struct dl_bw *dl_b, unsigned long cap, u64 old_bw, u64 new_bw)
228 : {
229 0 : return dl_b->bw != -1 &&
230 0 : cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw;
231 : }
232 :
233 : static inline
234 : void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
235 : {
236 0 : u64 old = dl_rq->running_bw;
237 :
238 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
239 0 : dl_rq->running_bw += dl_bw;
240 : SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */
241 0 : SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
242 : /* kick cpufreq (see the comment in kernel/sched/sched.h). */
243 0 : cpufreq_update_util(rq_of_dl_rq(dl_rq), 0);
244 : }
245 :
246 : static inline
247 : void __sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
248 : {
249 0 : u64 old = dl_rq->running_bw;
250 :
251 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
252 0 : dl_rq->running_bw -= dl_bw;
253 : SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */
254 0 : if (dl_rq->running_bw > old)
255 0 : dl_rq->running_bw = 0;
256 : /* kick cpufreq (see the comment in kernel/sched/sched.h). */
257 : cpufreq_update_util(rq_of_dl_rq(dl_rq), 0);
258 : }
259 :
260 : static inline
261 : void __add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
262 : {
263 0 : u64 old = dl_rq->this_bw;
264 :
265 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
266 0 : dl_rq->this_bw += dl_bw;
267 : SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */
268 : }
269 :
270 : static inline
271 : void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
272 : {
273 0 : u64 old = dl_rq->this_bw;
274 :
275 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
276 0 : dl_rq->this_bw -= dl_bw;
277 : SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */
278 0 : if (dl_rq->this_bw > old)
279 0 : dl_rq->this_bw = 0;
280 : SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
281 : }
282 :
283 : static inline
284 : void add_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
285 : {
286 0 : if (!dl_entity_is_special(dl_se))
287 0 : __add_rq_bw(dl_se->dl_bw, dl_rq);
288 : }
289 :
290 : static inline
291 : void sub_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
292 : {
293 0 : if (!dl_entity_is_special(dl_se))
294 0 : __sub_rq_bw(dl_se->dl_bw, dl_rq);
295 : }
296 :
297 : static inline
298 : void add_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
299 : {
300 0 : if (!dl_entity_is_special(dl_se))
301 0 : __add_running_bw(dl_se->dl_bw, dl_rq);
302 : }
303 :
304 : static inline
305 : void sub_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
306 : {
307 0 : if (!dl_entity_is_special(dl_se))
308 0 : __sub_running_bw(dl_se->dl_bw, dl_rq);
309 : }
310 :
311 0 : static void dl_change_utilization(struct task_struct *p, u64 new_bw)
312 : {
313 : struct rq *rq;
314 :
315 0 : WARN_ON_ONCE(p->dl.flags & SCHED_FLAG_SUGOV);
316 :
317 0 : if (task_on_rq_queued(p))
318 : return;
319 :
320 0 : rq = task_rq(p);
321 0 : if (p->dl.dl_non_contending) {
322 0 : sub_running_bw(&p->dl, &rq->dl);
323 0 : p->dl.dl_non_contending = 0;
324 : /*
325 : * If the timer handler is currently running and the
326 : * timer cannot be canceled, inactive_task_timer()
327 : * will see that dl_not_contending is not set, and
328 : * will not touch the rq's active utilization,
329 : * so we are still safe.
330 : */
331 0 : if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
332 0 : put_task_struct(p);
333 : }
334 0 : __sub_rq_bw(p->dl.dl_bw, &rq->dl);
335 0 : __add_rq_bw(new_bw, &rq->dl);
336 : }
337 :
338 : /*
339 : * The utilization of a task cannot be immediately removed from
340 : * the rq active utilization (running_bw) when the task blocks.
341 : * Instead, we have to wait for the so called "0-lag time".
342 : *
343 : * If a task blocks before the "0-lag time", a timer (the inactive
344 : * timer) is armed, and running_bw is decreased when the timer
345 : * fires.
346 : *
347 : * If the task wakes up again before the inactive timer fires,
348 : * the timer is canceled, whereas if the task wakes up after the
349 : * inactive timer fired (and running_bw has been decreased) the
350 : * task's utilization has to be added to running_bw again.
351 : * A flag in the deadline scheduling entity (dl_non_contending)
352 : * is used to avoid race conditions between the inactive timer handler
353 : * and task wakeups.
354 : *
355 : * The following diagram shows how running_bw is updated. A task is
356 : * "ACTIVE" when its utilization contributes to running_bw; an
357 : * "ACTIVE contending" task is in the TASK_RUNNING state, while an
358 : * "ACTIVE non contending" task is a blocked task for which the "0-lag time"
359 : * has not passed yet. An "INACTIVE" task is a task for which the "0-lag"
360 : * time already passed, which does not contribute to running_bw anymore.
361 : * +------------------+
362 : * wakeup | ACTIVE |
363 : * +------------------>+ contending |
364 : * | add_running_bw | |
365 : * | +----+------+------+
366 : * | | ^
367 : * | dequeue | |
368 : * +--------+-------+ | |
369 : * | | t >= 0-lag | | wakeup
370 : * | INACTIVE |<---------------+ |
371 : * | | sub_running_bw | |
372 : * +--------+-------+ | |
373 : * ^ | |
374 : * | t < 0-lag | |
375 : * | | |
376 : * | V |
377 : * | +----+------+------+
378 : * | sub_running_bw | ACTIVE |
379 : * +-------------------+ |
380 : * inactive timer | non contending |
381 : * fired +------------------+
382 : *
383 : * The task_non_contending() function is invoked when a task
384 : * blocks, and checks if the 0-lag time already passed or
385 : * not (in the first case, it directly updates running_bw;
386 : * in the second case, it arms the inactive timer).
387 : *
388 : * The task_contending() function is invoked when a task wakes
389 : * up, and checks if the task is still in the "ACTIVE non contending"
390 : * state or not (in the second case, it updates running_bw).
391 : */
392 0 : static void task_non_contending(struct task_struct *p)
393 : {
394 0 : struct sched_dl_entity *dl_se = &p->dl;
395 0 : struct hrtimer *timer = &dl_se->inactive_timer;
396 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
397 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
398 : s64 zerolag_time;
399 :
400 : /*
401 : * If this is a non-deadline task that has been boosted,
402 : * do nothing
403 : */
404 0 : if (dl_se->dl_runtime == 0)
405 : return;
406 :
407 0 : if (dl_entity_is_special(dl_se))
408 : return;
409 :
410 0 : WARN_ON(dl_se->dl_non_contending);
411 :
412 0 : zerolag_time = dl_se->deadline -
413 0 : div64_long((dl_se->runtime * dl_se->dl_period),
414 : dl_se->dl_runtime);
415 :
416 : /*
417 : * Using relative times instead of the absolute "0-lag time"
418 : * allows to simplify the code
419 : */
420 0 : zerolag_time -= rq_clock(rq);
421 :
422 : /*
423 : * If the "0-lag time" already passed, decrease the active
424 : * utilization now, instead of starting a timer
425 : */
426 0 : if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {
427 0 : if (dl_task(p))
428 0 : sub_running_bw(dl_se, dl_rq);
429 0 : if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
430 0 : struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
431 :
432 0 : if (READ_ONCE(p->__state) == TASK_DEAD)
433 0 : sub_rq_bw(&p->dl, &rq->dl);
434 0 : raw_spin_lock(&dl_b->lock);
435 0 : __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
436 0 : raw_spin_unlock(&dl_b->lock);
437 : __dl_clear_params(p);
438 : }
439 :
440 : return;
441 : }
442 :
443 0 : dl_se->dl_non_contending = 1;
444 0 : get_task_struct(p);
445 0 : hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL_HARD);
446 : }
447 :
448 0 : static void task_contending(struct sched_dl_entity *dl_se, int flags)
449 : {
450 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
451 :
452 : /*
453 : * If this is a non-deadline task that has been boosted,
454 : * do nothing
455 : */
456 0 : if (dl_se->dl_runtime == 0)
457 : return;
458 :
459 : if (flags & ENQUEUE_MIGRATED)
460 : add_rq_bw(dl_se, dl_rq);
461 :
462 0 : if (dl_se->dl_non_contending) {
463 0 : dl_se->dl_non_contending = 0;
464 : /*
465 : * If the timer handler is currently running and the
466 : * timer cannot be canceled, inactive_task_timer()
467 : * will see that dl_not_contending is not set, and
468 : * will not touch the rq's active utilization,
469 : * so we are still safe.
470 : */
471 0 : if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1)
472 0 : put_task_struct(dl_task_of(dl_se));
473 : } else {
474 : /*
475 : * Since "dl_non_contending" is not set, the
476 : * task's utilization has already been removed from
477 : * active utilization (either when the task blocked,
478 : * when the "inactive timer" fired).
479 : * So, add it back.
480 : */
481 0 : add_running_bw(dl_se, dl_rq);
482 : }
483 : }
484 :
485 : static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
486 : {
487 0 : struct sched_dl_entity *dl_se = &p->dl;
488 :
489 : return rb_first_cached(&dl_rq->root) == &dl_se->rb_node;
490 : }
491 :
492 : static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
493 :
494 1 : void init_dl_bw(struct dl_bw *dl_b)
495 : {
496 : raw_spin_lock_init(&dl_b->lock);
497 1 : if (global_rt_runtime() == RUNTIME_INF)
498 0 : dl_b->bw = -1;
499 : else
500 1 : dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
501 1 : dl_b->total_bw = 0;
502 1 : }
503 :
504 1 : void init_dl_rq(struct dl_rq *dl_rq)
505 : {
506 1 : dl_rq->root = RB_ROOT_CACHED;
507 :
508 : #ifdef CONFIG_SMP
509 : /* zero means no -deadline tasks */
510 : dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
511 :
512 : dl_rq->dl_nr_migratory = 0;
513 : dl_rq->overloaded = 0;
514 : dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED;
515 : #else
516 1 : init_dl_bw(&dl_rq->dl_bw);
517 : #endif
518 :
519 1 : dl_rq->running_bw = 0;
520 1 : dl_rq->this_bw = 0;
521 1 : init_dl_rq_bw_ratio(dl_rq);
522 1 : }
523 :
524 : #ifdef CONFIG_SMP
525 :
526 : static inline int dl_overloaded(struct rq *rq)
527 : {
528 : return atomic_read(&rq->rd->dlo_count);
529 : }
530 :
531 : static inline void dl_set_overload(struct rq *rq)
532 : {
533 : if (!rq->online)
534 : return;
535 :
536 : cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
537 : /*
538 : * Must be visible before the overload count is
539 : * set (as in sched_rt.c).
540 : *
541 : * Matched by the barrier in pull_dl_task().
542 : */
543 : smp_wmb();
544 : atomic_inc(&rq->rd->dlo_count);
545 : }
546 :
547 : static inline void dl_clear_overload(struct rq *rq)
548 : {
549 : if (!rq->online)
550 : return;
551 :
552 : atomic_dec(&rq->rd->dlo_count);
553 : cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
554 : }
555 :
556 : static void update_dl_migration(struct dl_rq *dl_rq)
557 : {
558 : if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) {
559 : if (!dl_rq->overloaded) {
560 : dl_set_overload(rq_of_dl_rq(dl_rq));
561 : dl_rq->overloaded = 1;
562 : }
563 : } else if (dl_rq->overloaded) {
564 : dl_clear_overload(rq_of_dl_rq(dl_rq));
565 : dl_rq->overloaded = 0;
566 : }
567 : }
568 :
569 : static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
570 : {
571 : struct task_struct *p = dl_task_of(dl_se);
572 :
573 : if (p->nr_cpus_allowed > 1)
574 : dl_rq->dl_nr_migratory++;
575 :
576 : update_dl_migration(dl_rq);
577 : }
578 :
579 : static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
580 : {
581 : struct task_struct *p = dl_task_of(dl_se);
582 :
583 : if (p->nr_cpus_allowed > 1)
584 : dl_rq->dl_nr_migratory--;
585 :
586 : update_dl_migration(dl_rq);
587 : }
588 :
589 : #define __node_2_pdl(node) \
590 : rb_entry((node), struct task_struct, pushable_dl_tasks)
591 :
592 : static inline bool __pushable_less(struct rb_node *a, const struct rb_node *b)
593 : {
594 : return dl_entity_preempt(&__node_2_pdl(a)->dl, &__node_2_pdl(b)->dl);
595 : }
596 :
597 : /*
598 : * The list of pushable -deadline task is not a plist, like in
599 : * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
600 : */
601 : static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
602 : {
603 : struct rb_node *leftmost;
604 :
605 : WARN_ON_ONCE(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
606 :
607 : leftmost = rb_add_cached(&p->pushable_dl_tasks,
608 : &rq->dl.pushable_dl_tasks_root,
609 : __pushable_less);
610 : if (leftmost)
611 : rq->dl.earliest_dl.next = p->dl.deadline;
612 : }
613 :
614 : static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
615 : {
616 : struct dl_rq *dl_rq = &rq->dl;
617 : struct rb_root_cached *root = &dl_rq->pushable_dl_tasks_root;
618 : struct rb_node *leftmost;
619 :
620 : if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
621 : return;
622 :
623 : leftmost = rb_erase_cached(&p->pushable_dl_tasks, root);
624 : if (leftmost)
625 : dl_rq->earliest_dl.next = __node_2_pdl(leftmost)->dl.deadline;
626 :
627 : RB_CLEAR_NODE(&p->pushable_dl_tasks);
628 : }
629 :
630 : static inline int has_pushable_dl_tasks(struct rq *rq)
631 : {
632 : return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root);
633 : }
634 :
635 : static int push_dl_task(struct rq *rq);
636 :
637 : static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
638 : {
639 : return rq->online && dl_task(prev);
640 : }
641 :
642 : static DEFINE_PER_CPU(struct balance_callback, dl_push_head);
643 : static DEFINE_PER_CPU(struct balance_callback, dl_pull_head);
644 :
645 : static void push_dl_tasks(struct rq *);
646 : static void pull_dl_task(struct rq *);
647 :
648 : static inline void deadline_queue_push_tasks(struct rq *rq)
649 : {
650 : if (!has_pushable_dl_tasks(rq))
651 : return;
652 :
653 : queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks);
654 : }
655 :
656 : static inline void deadline_queue_pull_task(struct rq *rq)
657 : {
658 : queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task);
659 : }
660 :
661 : static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
662 :
663 : static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p)
664 : {
665 : struct rq *later_rq = NULL;
666 : struct dl_bw *dl_b;
667 :
668 : later_rq = find_lock_later_rq(p, rq);
669 : if (!later_rq) {
670 : int cpu;
671 :
672 : /*
673 : * If we cannot preempt any rq, fall back to pick any
674 : * online CPU:
675 : */
676 : cpu = cpumask_any_and(cpu_active_mask, p->cpus_ptr);
677 : if (cpu >= nr_cpu_ids) {
678 : /*
679 : * Failed to find any suitable CPU.
680 : * The task will never come back!
681 : */
682 : WARN_ON_ONCE(dl_bandwidth_enabled());
683 :
684 : /*
685 : * If admission control is disabled we
686 : * try a little harder to let the task
687 : * run.
688 : */
689 : cpu = cpumask_any(cpu_active_mask);
690 : }
691 : later_rq = cpu_rq(cpu);
692 : double_lock_balance(rq, later_rq);
693 : }
694 :
695 : if (p->dl.dl_non_contending || p->dl.dl_throttled) {
696 : /*
697 : * Inactive timer is armed (or callback is running, but
698 : * waiting for us to release rq locks). In any case, when it
699 : * will fire (or continue), it will see running_bw of this
700 : * task migrated to later_rq (and correctly handle it).
701 : */
702 : sub_running_bw(&p->dl, &rq->dl);
703 : sub_rq_bw(&p->dl, &rq->dl);
704 :
705 : add_rq_bw(&p->dl, &later_rq->dl);
706 : add_running_bw(&p->dl, &later_rq->dl);
707 : } else {
708 : sub_rq_bw(&p->dl, &rq->dl);
709 : add_rq_bw(&p->dl, &later_rq->dl);
710 : }
711 :
712 : /*
713 : * And we finally need to fixup root_domain(s) bandwidth accounting,
714 : * since p is still hanging out in the old (now moved to default) root
715 : * domain.
716 : */
717 : dl_b = &rq->rd->dl_bw;
718 : raw_spin_lock(&dl_b->lock);
719 : __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
720 : raw_spin_unlock(&dl_b->lock);
721 :
722 : dl_b = &later_rq->rd->dl_bw;
723 : raw_spin_lock(&dl_b->lock);
724 : __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(later_rq->rd->span));
725 : raw_spin_unlock(&dl_b->lock);
726 :
727 : set_task_cpu(p, later_rq->cpu);
728 : double_unlock_balance(later_rq, rq);
729 :
730 : return later_rq;
731 : }
732 :
733 : #else
734 :
735 : static inline
736 : void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
737 : {
738 : }
739 :
740 : static inline
741 : void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
742 : {
743 : }
744 :
745 : static inline
746 : void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
747 : {
748 : }
749 :
750 : static inline
751 : void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
752 : {
753 : }
754 :
755 : static inline void deadline_queue_push_tasks(struct rq *rq)
756 : {
757 : }
758 :
759 : static inline void deadline_queue_pull_task(struct rq *rq)
760 : {
761 : }
762 : #endif /* CONFIG_SMP */
763 :
764 : static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
765 : static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
766 : static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, int flags);
767 :
768 : static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
769 : struct rq *rq)
770 : {
771 : /* for non-boosted task, pi_of(dl_se) == dl_se */
772 0 : dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline;
773 0 : dl_se->runtime = pi_of(dl_se)->dl_runtime;
774 : }
775 :
776 : /*
777 : * We are being explicitly informed that a new instance is starting,
778 : * and this means that:
779 : * - the absolute deadline of the entity has to be placed at
780 : * current time + relative deadline;
781 : * - the runtime of the entity has to be set to the maximum value.
782 : *
783 : * The capability of specifying such event is useful whenever a -deadline
784 : * entity wants to (try to!) synchronize its behaviour with the scheduler's
785 : * one, and to (try to!) reconcile itself with its own scheduling
786 : * parameters.
787 : */
788 0 : static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
789 : {
790 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
791 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
792 :
793 0 : WARN_ON(is_dl_boosted(dl_se));
794 0 : WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
795 :
796 : /*
797 : * We are racing with the deadline timer. So, do nothing because
798 : * the deadline timer handler will take care of properly recharging
799 : * the runtime and postponing the deadline
800 : */
801 0 : if (dl_se->dl_throttled)
802 : return;
803 :
804 : /*
805 : * We use the regular wall clock time to set deadlines in the
806 : * future; in fact, we must consider execution overheads (time
807 : * spent on hardirq context, etc.).
808 : */
809 : replenish_dl_new_period(dl_se, rq);
810 : }
811 :
812 : /*
813 : * Pure Earliest Deadline First (EDF) scheduling does not deal with the
814 : * possibility of a entity lasting more than what it declared, and thus
815 : * exhausting its runtime.
816 : *
817 : * Here we are interested in making runtime overrun possible, but we do
818 : * not want a entity which is misbehaving to affect the scheduling of all
819 : * other entities.
820 : * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
821 : * is used, in order to confine each entity within its own bandwidth.
822 : *
823 : * This function deals exactly with that, and ensures that when the runtime
824 : * of a entity is replenished, its deadline is also postponed. That ensures
825 : * the overrunning entity can't interfere with other entity in the system and
826 : * can't make them miss their deadlines. Reasons why this kind of overruns
827 : * could happen are, typically, a entity voluntarily trying to overcome its
828 : * runtime, or it just underestimated it during sched_setattr().
829 : */
830 0 : static void replenish_dl_entity(struct sched_dl_entity *dl_se)
831 : {
832 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
833 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
834 :
835 0 : WARN_ON_ONCE(pi_of(dl_se)->dl_runtime <= 0);
836 :
837 : /*
838 : * This could be the case for a !-dl task that is boosted.
839 : * Just go with full inherited parameters.
840 : */
841 0 : if (dl_se->dl_deadline == 0)
842 : replenish_dl_new_period(dl_se, rq);
843 :
844 0 : if (dl_se->dl_yielded && dl_se->runtime > 0)
845 0 : dl_se->runtime = 0;
846 :
847 : /*
848 : * We keep moving the deadline away until we get some
849 : * available runtime for the entity. This ensures correct
850 : * handling of situations where the runtime overrun is
851 : * arbitrary large.
852 : */
853 0 : while (dl_se->runtime <= 0) {
854 0 : dl_se->deadline += pi_of(dl_se)->dl_period;
855 0 : dl_se->runtime += pi_of(dl_se)->dl_runtime;
856 : }
857 :
858 : /*
859 : * At this point, the deadline really should be "in
860 : * the future" with respect to rq->clock. If it's
861 : * not, we are, for some reason, lagging too much!
862 : * Anyway, after having warn userspace abut that,
863 : * we still try to keep the things running by
864 : * resetting the deadline and the budget of the
865 : * entity.
866 : */
867 0 : if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
868 0 : printk_deferred_once("sched: DL replenish lagged too much\n");
869 : replenish_dl_new_period(dl_se, rq);
870 : }
871 :
872 0 : if (dl_se->dl_yielded)
873 0 : dl_se->dl_yielded = 0;
874 0 : if (dl_se->dl_throttled)
875 0 : dl_se->dl_throttled = 0;
876 0 : }
877 :
878 : /*
879 : * Here we check if --at time t-- an entity (which is probably being
880 : * [re]activated or, in general, enqueued) can use its remaining runtime
881 : * and its current deadline _without_ exceeding the bandwidth it is
882 : * assigned (function returns true if it can't). We are in fact applying
883 : * one of the CBS rules: when a task wakes up, if the residual runtime
884 : * over residual deadline fits within the allocated bandwidth, then we
885 : * can keep the current (absolute) deadline and residual budget without
886 : * disrupting the schedulability of the system. Otherwise, we should
887 : * refill the runtime and set the deadline a period in the future,
888 : * because keeping the current (absolute) deadline of the task would
889 : * result in breaking guarantees promised to other tasks (refer to
890 : * Documentation/scheduler/sched-deadline.rst for more information).
891 : *
892 : * This function returns true if:
893 : *
894 : * runtime / (deadline - t) > dl_runtime / dl_deadline ,
895 : *
896 : * IOW we can't recycle current parameters.
897 : *
898 : * Notice that the bandwidth check is done against the deadline. For
899 : * task with deadline equal to period this is the same of using
900 : * dl_period instead of dl_deadline in the equation above.
901 : */
902 : static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
903 : {
904 : u64 left, right;
905 :
906 : /*
907 : * left and right are the two sides of the equation above,
908 : * after a bit of shuffling to use multiplications instead
909 : * of divisions.
910 : *
911 : * Note that none of the time values involved in the two
912 : * multiplications are absolute: dl_deadline and dl_runtime
913 : * are the relative deadline and the maximum runtime of each
914 : * instance, runtime is the runtime left for the last instance
915 : * and (deadline - t), since t is rq->clock, is the time left
916 : * to the (absolute) deadline. Even if overflowing the u64 type
917 : * is very unlikely to occur in both cases, here we scale down
918 : * as we want to avoid that risk at all. Scaling down by 10
919 : * means that we reduce granularity to 1us. We are fine with it,
920 : * since this is only a true/false check and, anyway, thinking
921 : * of anything below microseconds resolution is actually fiction
922 : * (but still we want to give the user that illusion >;).
923 : */
924 0 : left = (pi_of(dl_se)->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
925 0 : right = ((dl_se->deadline - t) >> DL_SCALE) *
926 0 : (pi_of(dl_se)->dl_runtime >> DL_SCALE);
927 :
928 0 : return dl_time_before(right, left);
929 : }
930 :
931 : /*
932 : * Revised wakeup rule [1]: For self-suspending tasks, rather then
933 : * re-initializing task's runtime and deadline, the revised wakeup
934 : * rule adjusts the task's runtime to avoid the task to overrun its
935 : * density.
936 : *
937 : * Reasoning: a task may overrun the density if:
938 : * runtime / (deadline - t) > dl_runtime / dl_deadline
939 : *
940 : * Therefore, runtime can be adjusted to:
941 : * runtime = (dl_runtime / dl_deadline) * (deadline - t)
942 : *
943 : * In such way that runtime will be equal to the maximum density
944 : * the task can use without breaking any rule.
945 : *
946 : * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant
947 : * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24.
948 : */
949 : static void
950 0 : update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq)
951 : {
952 0 : u64 laxity = dl_se->deadline - rq_clock(rq);
953 :
954 : /*
955 : * If the task has deadline < period, and the deadline is in the past,
956 : * it should already be throttled before this check.
957 : *
958 : * See update_dl_entity() comments for further details.
959 : */
960 0 : WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq)));
961 :
962 0 : dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT;
963 0 : }
964 :
965 : /*
966 : * Regarding the deadline, a task with implicit deadline has a relative
967 : * deadline == relative period. A task with constrained deadline has a
968 : * relative deadline <= relative period.
969 : *
970 : * We support constrained deadline tasks. However, there are some restrictions
971 : * applied only for tasks which do not have an implicit deadline. See
972 : * update_dl_entity() to know more about such restrictions.
973 : *
974 : * The dl_is_implicit() returns true if the task has an implicit deadline.
975 : */
976 : static inline bool dl_is_implicit(struct sched_dl_entity *dl_se)
977 : {
978 : return dl_se->dl_deadline == dl_se->dl_period;
979 : }
980 :
981 : /*
982 : * When a deadline entity is placed in the runqueue, its runtime and deadline
983 : * might need to be updated. This is done by a CBS wake up rule. There are two
984 : * different rules: 1) the original CBS; and 2) the Revisited CBS.
985 : *
986 : * When the task is starting a new period, the Original CBS is used. In this
987 : * case, the runtime is replenished and a new absolute deadline is set.
988 : *
989 : * When a task is queued before the begin of the next period, using the
990 : * remaining runtime and deadline could make the entity to overflow, see
991 : * dl_entity_overflow() to find more about runtime overflow. When such case
992 : * is detected, the runtime and deadline need to be updated.
993 : *
994 : * If the task has an implicit deadline, i.e., deadline == period, the Original
995 : * CBS is applied. the runtime is replenished and a new absolute deadline is
996 : * set, as in the previous cases.
997 : *
998 : * However, the Original CBS does not work properly for tasks with
999 : * deadline < period, which are said to have a constrained deadline. By
1000 : * applying the Original CBS, a constrained deadline task would be able to run
1001 : * runtime/deadline in a period. With deadline < period, the task would
1002 : * overrun the runtime/period allowed bandwidth, breaking the admission test.
1003 : *
1004 : * In order to prevent this misbehave, the Revisited CBS is used for
1005 : * constrained deadline tasks when a runtime overflow is detected. In the
1006 : * Revisited CBS, rather than replenishing & setting a new absolute deadline,
1007 : * the remaining runtime of the task is reduced to avoid runtime overflow.
1008 : * Please refer to the comments update_dl_revised_wakeup() function to find
1009 : * more about the Revised CBS rule.
1010 : */
1011 0 : static void update_dl_entity(struct sched_dl_entity *dl_se)
1012 : {
1013 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1014 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
1015 :
1016 0 : if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
1017 0 : dl_entity_overflow(dl_se, rq_clock(rq))) {
1018 :
1019 0 : if (unlikely(!dl_is_implicit(dl_se) &&
1020 : !dl_time_before(dl_se->deadline, rq_clock(rq)) &&
1021 : !is_dl_boosted(dl_se))) {
1022 0 : update_dl_revised_wakeup(dl_se, rq);
1023 0 : return;
1024 : }
1025 :
1026 : replenish_dl_new_period(dl_se, rq);
1027 : }
1028 : }
1029 :
1030 : static inline u64 dl_next_period(struct sched_dl_entity *dl_se)
1031 : {
1032 0 : return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period;
1033 : }
1034 :
1035 : /*
1036 : * If the entity depleted all its runtime, and if we want it to sleep
1037 : * while waiting for some new execution time to become available, we
1038 : * set the bandwidth replenishment timer to the replenishment instant
1039 : * and try to activate it.
1040 : *
1041 : * Notice that it is important for the caller to know if the timer
1042 : * actually started or not (i.e., the replenishment instant is in
1043 : * the future or in the past).
1044 : */
1045 0 : static int start_dl_timer(struct task_struct *p)
1046 : {
1047 0 : struct sched_dl_entity *dl_se = &p->dl;
1048 0 : struct hrtimer *timer = &dl_se->dl_timer;
1049 0 : struct rq *rq = task_rq(p);
1050 : ktime_t now, act;
1051 : s64 delta;
1052 :
1053 0 : lockdep_assert_rq_held(rq);
1054 :
1055 : /*
1056 : * We want the timer to fire at the deadline, but considering
1057 : * that it is actually coming from rq->clock and not from
1058 : * hrtimer's time base reading.
1059 : */
1060 0 : act = ns_to_ktime(dl_next_period(dl_se));
1061 0 : now = hrtimer_cb_get_time(timer);
1062 0 : delta = ktime_to_ns(now) - rq_clock(rq);
1063 0 : act = ktime_add_ns(act, delta);
1064 :
1065 : /*
1066 : * If the expiry time already passed, e.g., because the value
1067 : * chosen as the deadline is too small, don't even try to
1068 : * start the timer in the past!
1069 : */
1070 0 : if (ktime_us_delta(act, now) < 0)
1071 : return 0;
1072 :
1073 : /*
1074 : * !enqueued will guarantee another callback; even if one is already in
1075 : * progress. This ensures a balanced {get,put}_task_struct().
1076 : *
1077 : * The race against __run_timer() clearing the enqueued state is
1078 : * harmless because we're holding task_rq()->lock, therefore the timer
1079 : * expiring after we've done the check will wait on its task_rq_lock()
1080 : * and observe our state.
1081 : */
1082 0 : if (!hrtimer_is_queued(timer)) {
1083 0 : get_task_struct(p);
1084 : hrtimer_start(timer, act, HRTIMER_MODE_ABS_HARD);
1085 : }
1086 :
1087 : return 1;
1088 : }
1089 :
1090 : /*
1091 : * This is the bandwidth enforcement timer callback. If here, we know
1092 : * a task is not on its dl_rq, since the fact that the timer was running
1093 : * means the task is throttled and needs a runtime replenishment.
1094 : *
1095 : * However, what we actually do depends on the fact the task is active,
1096 : * (it is on its rq) or has been removed from there by a call to
1097 : * dequeue_task_dl(). In the former case we must issue the runtime
1098 : * replenishment and add the task back to the dl_rq; in the latter, we just
1099 : * do nothing but clearing dl_throttled, so that runtime and deadline
1100 : * updating (and the queueing back to dl_rq) will be done by the
1101 : * next call to enqueue_task_dl().
1102 : */
1103 0 : static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
1104 : {
1105 0 : struct sched_dl_entity *dl_se = container_of(timer,
1106 : struct sched_dl_entity,
1107 : dl_timer);
1108 0 : struct task_struct *p = dl_task_of(dl_se);
1109 : struct rq_flags rf;
1110 : struct rq *rq;
1111 :
1112 0 : rq = task_rq_lock(p, &rf);
1113 :
1114 : /*
1115 : * The task might have changed its scheduling policy to something
1116 : * different than SCHED_DEADLINE (through switched_from_dl()).
1117 : */
1118 0 : if (!dl_task(p))
1119 : goto unlock;
1120 :
1121 : /*
1122 : * The task might have been boosted by someone else and might be in the
1123 : * boosting/deboosting path, its not throttled.
1124 : */
1125 0 : if (is_dl_boosted(dl_se))
1126 : goto unlock;
1127 :
1128 : /*
1129 : * Spurious timer due to start_dl_timer() race; or we already received
1130 : * a replenishment from rt_mutex_setprio().
1131 : */
1132 0 : if (!dl_se->dl_throttled)
1133 : goto unlock;
1134 :
1135 : sched_clock_tick();
1136 0 : update_rq_clock(rq);
1137 :
1138 : /*
1139 : * If the throttle happened during sched-out; like:
1140 : *
1141 : * schedule()
1142 : * deactivate_task()
1143 : * dequeue_task_dl()
1144 : * update_curr_dl()
1145 : * start_dl_timer()
1146 : * __dequeue_task_dl()
1147 : * prev->on_rq = 0;
1148 : *
1149 : * We can be both throttled and !queued. Replenish the counter
1150 : * but do not enqueue -- wait for our wakeup to do that.
1151 : */
1152 0 : if (!task_on_rq_queued(p)) {
1153 0 : replenish_dl_entity(dl_se);
1154 0 : goto unlock;
1155 : }
1156 :
1157 : #ifdef CONFIG_SMP
1158 : if (unlikely(!rq->online)) {
1159 : /*
1160 : * If the runqueue is no longer available, migrate the
1161 : * task elsewhere. This necessarily changes rq.
1162 : */
1163 : lockdep_unpin_lock(__rq_lockp(rq), rf.cookie);
1164 : rq = dl_task_offline_migration(rq, p);
1165 : rf.cookie = lockdep_pin_lock(__rq_lockp(rq));
1166 : update_rq_clock(rq);
1167 :
1168 : /*
1169 : * Now that the task has been migrated to the new RQ and we
1170 : * have that locked, proceed as normal and enqueue the task
1171 : * there.
1172 : */
1173 : }
1174 : #endif
1175 :
1176 0 : enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
1177 0 : if (dl_task(rq->curr))
1178 : check_preempt_curr_dl(rq, p, 0);
1179 : else
1180 0 : resched_curr(rq);
1181 :
1182 : #ifdef CONFIG_SMP
1183 : /*
1184 : * Queueing this task back might have overloaded rq, check if we need
1185 : * to kick someone away.
1186 : */
1187 : if (has_pushable_dl_tasks(rq)) {
1188 : /*
1189 : * Nothing relies on rq->lock after this, so its safe to drop
1190 : * rq->lock.
1191 : */
1192 : rq_unpin_lock(rq, &rf);
1193 : push_dl_task(rq);
1194 : rq_repin_lock(rq, &rf);
1195 : }
1196 : #endif
1197 :
1198 : unlock:
1199 0 : task_rq_unlock(rq, p, &rf);
1200 :
1201 : /*
1202 : * This can free the task_struct, including this hrtimer, do not touch
1203 : * anything related to that after this.
1204 : */
1205 0 : put_task_struct(p);
1206 :
1207 0 : return HRTIMER_NORESTART;
1208 : }
1209 :
1210 176 : void init_dl_task_timer(struct sched_dl_entity *dl_se)
1211 : {
1212 176 : struct hrtimer *timer = &dl_se->dl_timer;
1213 :
1214 176 : hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1215 176 : timer->function = dl_task_timer;
1216 176 : }
1217 :
1218 : /*
1219 : * During the activation, CBS checks if it can reuse the current task's
1220 : * runtime and period. If the deadline of the task is in the past, CBS
1221 : * cannot use the runtime, and so it replenishes the task. This rule
1222 : * works fine for implicit deadline tasks (deadline == period), and the
1223 : * CBS was designed for implicit deadline tasks. However, a task with
1224 : * constrained deadline (deadline < period) might be awakened after the
1225 : * deadline, but before the next period. In this case, replenishing the
1226 : * task would allow it to run for runtime / deadline. As in this case
1227 : * deadline < period, CBS enables a task to run for more than the
1228 : * runtime / period. In a very loaded system, this can cause a domino
1229 : * effect, making other tasks miss their deadlines.
1230 : *
1231 : * To avoid this problem, in the activation of a constrained deadline
1232 : * task after the deadline but before the next period, throttle the
1233 : * task and set the replenishing timer to the begin of the next period,
1234 : * unless it is boosted.
1235 : */
1236 0 : static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
1237 : {
1238 0 : struct task_struct *p = dl_task_of(dl_se);
1239 0 : struct rq *rq = rq_of_dl_rq(dl_rq_of_se(dl_se));
1240 :
1241 0 : if (dl_time_before(dl_se->deadline, rq_clock(rq)) &&
1242 0 : dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
1243 0 : if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(p)))
1244 : return;
1245 0 : dl_se->dl_throttled = 1;
1246 0 : if (dl_se->runtime > 0)
1247 0 : dl_se->runtime = 0;
1248 : }
1249 : }
1250 :
1251 : static
1252 : int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
1253 : {
1254 : return (dl_se->runtime <= 0);
1255 : }
1256 :
1257 : /*
1258 : * This function implements the GRUB accounting rule. According to the
1259 : * GRUB reclaiming algorithm, the runtime is not decreased as "dq = -dt",
1260 : * but as "dq = -(max{u, (Umax - Uinact - Uextra)} / Umax) dt",
1261 : * where u is the utilization of the task, Umax is the maximum reclaimable
1262 : * utilization, Uinact is the (per-runqueue) inactive utilization, computed
1263 : * as the difference between the "total runqueue utilization" and the
1264 : * "runqueue active utilization", and Uextra is the (per runqueue) extra
1265 : * reclaimable utilization.
1266 : * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations multiplied
1267 : * by 2^BW_SHIFT, the result has to be shifted right by BW_SHIFT.
1268 : * Since rq->dl.bw_ratio contains 1 / Umax multiplied by 2^RATIO_SHIFT, dl_bw
1269 : * is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
1270 : * Since delta is a 64 bit variable, to have an overflow its value should be
1271 : * larger than 2^(64 - 20 - 8), which is more than 64 seconds. So, overflow is
1272 : * not an issue here.
1273 : */
1274 : static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se)
1275 : {
1276 : u64 u_act;
1277 0 : u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */
1278 :
1279 : /*
1280 : * Instead of computing max{u, (u_max - u_inact - u_extra)}, we
1281 : * compare u_inact + u_extra with u_max - u, because u_inact + u_extra
1282 : * can be larger than u_max. So, u_max - u_inact - u_extra would be
1283 : * negative leading to wrong results.
1284 : */
1285 0 : if (u_inact + rq->dl.extra_bw > rq->dl.max_bw - dl_se->dl_bw)
1286 : u_act = dl_se->dl_bw;
1287 : else
1288 0 : u_act = rq->dl.max_bw - u_inact - rq->dl.extra_bw;
1289 :
1290 0 : u_act = (u_act * rq->dl.bw_ratio) >> RATIO_SHIFT;
1291 0 : return (delta * u_act) >> BW_SHIFT;
1292 : }
1293 :
1294 : /*
1295 : * Update the current task's runtime statistics (provided it is still
1296 : * a -deadline task and has not been removed from the dl_rq).
1297 : */
1298 0 : static void update_curr_dl(struct rq *rq)
1299 : {
1300 0 : struct task_struct *curr = rq->curr;
1301 0 : struct sched_dl_entity *dl_se = &curr->dl;
1302 : u64 delta_exec, scaled_delta_exec;
1303 0 : int cpu = cpu_of(rq);
1304 : u64 now;
1305 :
1306 0 : if (!dl_task(curr) || !on_dl_rq(dl_se))
1307 : return;
1308 :
1309 : /*
1310 : * Consumed budget is computed considering the time as
1311 : * observed by schedulable tasks (excluding time spent
1312 : * in hardirq context, etc.). Deadlines are instead
1313 : * computed using hard walltime. This seems to be the more
1314 : * natural solution, but the full ramifications of this
1315 : * approach need further study.
1316 : */
1317 0 : now = rq_clock_task(rq);
1318 0 : delta_exec = now - curr->se.exec_start;
1319 0 : if (unlikely((s64)delta_exec <= 0)) {
1320 0 : if (unlikely(dl_se->dl_yielded))
1321 : goto throttle;
1322 : return;
1323 : }
1324 :
1325 : schedstat_set(curr->stats.exec_max,
1326 : max(curr->stats.exec_max, delta_exec));
1327 :
1328 0 : trace_sched_stat_runtime(curr, delta_exec, 0);
1329 :
1330 0 : update_current_exec_runtime(curr, now, delta_exec);
1331 :
1332 0 : if (dl_entity_is_special(dl_se))
1333 : return;
1334 :
1335 : /*
1336 : * For tasks that participate in GRUB, we implement GRUB-PA: the
1337 : * spare reclaimed bandwidth is used to clock down frequency.
1338 : *
1339 : * For the others, we still need to scale reservation parameters
1340 : * according to current frequency and CPU maximum capacity.
1341 : */
1342 0 : if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM)) {
1343 0 : scaled_delta_exec = grub_reclaim(delta_exec,
1344 : rq,
1345 : &curr->dl);
1346 : } else {
1347 0 : unsigned long scale_freq = arch_scale_freq_capacity(cpu);
1348 0 : unsigned long scale_cpu = arch_scale_cpu_capacity(cpu);
1349 :
1350 0 : scaled_delta_exec = cap_scale(delta_exec, scale_freq);
1351 0 : scaled_delta_exec = cap_scale(scaled_delta_exec, scale_cpu);
1352 : }
1353 :
1354 0 : dl_se->runtime -= scaled_delta_exec;
1355 :
1356 : throttle:
1357 0 : if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
1358 0 : dl_se->dl_throttled = 1;
1359 :
1360 : /* If requested, inform the user about runtime overruns. */
1361 0 : if (dl_runtime_exceeded(dl_se) &&
1362 0 : (dl_se->flags & SCHED_FLAG_DL_OVERRUN))
1363 0 : dl_se->dl_overrun = 1;
1364 :
1365 0 : __dequeue_task_dl(rq, curr, 0);
1366 0 : if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(curr)))
1367 0 : enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
1368 :
1369 0 : if (!is_leftmost(curr, &rq->dl))
1370 0 : resched_curr(rq);
1371 : }
1372 :
1373 : /*
1374 : * Because -- for now -- we share the rt bandwidth, we need to
1375 : * account our runtime there too, otherwise actual rt tasks
1376 : * would be able to exceed the shared quota.
1377 : *
1378 : * Account to the root rt group for now.
1379 : *
1380 : * The solution we're working towards is having the RT groups scheduled
1381 : * using deadline servers -- however there's a few nasties to figure
1382 : * out before that can happen.
1383 : */
1384 0 : if (rt_bandwidth_enabled()) {
1385 0 : struct rt_rq *rt_rq = &rq->rt;
1386 :
1387 0 : raw_spin_lock(&rt_rq->rt_runtime_lock);
1388 : /*
1389 : * We'll let actual RT tasks worry about the overflow here, we
1390 : * have our own CBS to keep us inline; only account when RT
1391 : * bandwidth is relevant.
1392 : */
1393 0 : if (sched_rt_bandwidth_account(rt_rq))
1394 0 : rt_rq->rt_time += delta_exec;
1395 0 : raw_spin_unlock(&rt_rq->rt_runtime_lock);
1396 : }
1397 : }
1398 :
1399 0 : static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
1400 : {
1401 0 : struct sched_dl_entity *dl_se = container_of(timer,
1402 : struct sched_dl_entity,
1403 : inactive_timer);
1404 0 : struct task_struct *p = dl_task_of(dl_se);
1405 : struct rq_flags rf;
1406 : struct rq *rq;
1407 :
1408 0 : rq = task_rq_lock(p, &rf);
1409 :
1410 : sched_clock_tick();
1411 0 : update_rq_clock(rq);
1412 :
1413 0 : if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
1414 0 : struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1415 :
1416 0 : if (READ_ONCE(p->__state) == TASK_DEAD && dl_se->dl_non_contending) {
1417 0 : sub_running_bw(&p->dl, dl_rq_of_se(&p->dl));
1418 0 : sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl));
1419 0 : dl_se->dl_non_contending = 0;
1420 : }
1421 :
1422 0 : raw_spin_lock(&dl_b->lock);
1423 0 : __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
1424 0 : raw_spin_unlock(&dl_b->lock);
1425 : __dl_clear_params(p);
1426 :
1427 : goto unlock;
1428 : }
1429 0 : if (dl_se->dl_non_contending == 0)
1430 : goto unlock;
1431 :
1432 0 : sub_running_bw(dl_se, &rq->dl);
1433 0 : dl_se->dl_non_contending = 0;
1434 : unlock:
1435 0 : task_rq_unlock(rq, p, &rf);
1436 0 : put_task_struct(p);
1437 :
1438 0 : return HRTIMER_NORESTART;
1439 : }
1440 :
1441 176 : void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se)
1442 : {
1443 176 : struct hrtimer *timer = &dl_se->inactive_timer;
1444 :
1445 176 : hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1446 176 : timer->function = inactive_task_timer;
1447 176 : }
1448 :
1449 : #define __node_2_dle(node) \
1450 : rb_entry((node), struct sched_dl_entity, rb_node)
1451 :
1452 : #ifdef CONFIG_SMP
1453 :
1454 : static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
1455 : {
1456 : struct rq *rq = rq_of_dl_rq(dl_rq);
1457 :
1458 : if (dl_rq->earliest_dl.curr == 0 ||
1459 : dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
1460 : if (dl_rq->earliest_dl.curr == 0)
1461 : cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER);
1462 : dl_rq->earliest_dl.curr = deadline;
1463 : cpudl_set(&rq->rd->cpudl, rq->cpu, deadline);
1464 : }
1465 : }
1466 :
1467 : static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
1468 : {
1469 : struct rq *rq = rq_of_dl_rq(dl_rq);
1470 :
1471 : /*
1472 : * Since we may have removed our earliest (and/or next earliest)
1473 : * task we must recompute them.
1474 : */
1475 : if (!dl_rq->dl_nr_running) {
1476 : dl_rq->earliest_dl.curr = 0;
1477 : dl_rq->earliest_dl.next = 0;
1478 : cpudl_clear(&rq->rd->cpudl, rq->cpu);
1479 : cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1480 : } else {
1481 : struct rb_node *leftmost = rb_first_cached(&dl_rq->root);
1482 : struct sched_dl_entity *entry = __node_2_dle(leftmost);
1483 :
1484 : dl_rq->earliest_dl.curr = entry->deadline;
1485 : cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
1486 : }
1487 : }
1488 :
1489 : #else
1490 :
1491 : static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
1492 : static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
1493 :
1494 : #endif /* CONFIG_SMP */
1495 :
1496 : static inline
1497 0 : void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
1498 : {
1499 0 : int prio = dl_task_of(dl_se)->prio;
1500 0 : u64 deadline = dl_se->deadline;
1501 :
1502 0 : WARN_ON(!dl_prio(prio));
1503 0 : dl_rq->dl_nr_running++;
1504 0 : add_nr_running(rq_of_dl_rq(dl_rq), 1);
1505 :
1506 0 : inc_dl_deadline(dl_rq, deadline);
1507 0 : inc_dl_migration(dl_se, dl_rq);
1508 0 : }
1509 :
1510 : static inline
1511 0 : void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
1512 : {
1513 0 : int prio = dl_task_of(dl_se)->prio;
1514 :
1515 0 : WARN_ON(!dl_prio(prio));
1516 0 : WARN_ON(!dl_rq->dl_nr_running);
1517 0 : dl_rq->dl_nr_running--;
1518 0 : sub_nr_running(rq_of_dl_rq(dl_rq), 1);
1519 :
1520 0 : dec_dl_deadline(dl_rq, dl_se->deadline);
1521 0 : dec_dl_migration(dl_se, dl_rq);
1522 0 : }
1523 :
1524 : static inline bool __dl_less(struct rb_node *a, const struct rb_node *b)
1525 : {
1526 0 : return dl_time_before(__node_2_dle(a)->deadline, __node_2_dle(b)->deadline);
1527 : }
1528 :
1529 : static inline struct sched_statistics *
1530 : __schedstats_from_dl_se(struct sched_dl_entity *dl_se)
1531 : {
1532 : return &dl_task_of(dl_se)->stats;
1533 : }
1534 :
1535 : static inline void
1536 : update_stats_wait_start_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1537 : {
1538 : struct sched_statistics *stats;
1539 :
1540 : if (!schedstat_enabled())
1541 : return;
1542 :
1543 : stats = __schedstats_from_dl_se(dl_se);
1544 : __update_stats_wait_start(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1545 : }
1546 :
1547 : static inline void
1548 : update_stats_wait_end_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1549 : {
1550 : struct sched_statistics *stats;
1551 :
1552 : if (!schedstat_enabled())
1553 : return;
1554 :
1555 : stats = __schedstats_from_dl_se(dl_se);
1556 : __update_stats_wait_end(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1557 : }
1558 :
1559 : static inline void
1560 : update_stats_enqueue_sleeper_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1561 : {
1562 : struct sched_statistics *stats;
1563 :
1564 : if (!schedstat_enabled())
1565 : return;
1566 :
1567 : stats = __schedstats_from_dl_se(dl_se);
1568 : __update_stats_enqueue_sleeper(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1569 : }
1570 :
1571 : static inline void
1572 : update_stats_enqueue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1573 : int flags)
1574 : {
1575 : if (!schedstat_enabled())
1576 : return;
1577 :
1578 : if (flags & ENQUEUE_WAKEUP)
1579 : update_stats_enqueue_sleeper_dl(dl_rq, dl_se);
1580 : }
1581 :
1582 : static inline void
1583 : update_stats_dequeue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1584 : int flags)
1585 : {
1586 0 : struct task_struct *p = dl_task_of(dl_se);
1587 :
1588 : if (!schedstat_enabled())
1589 : return;
1590 :
1591 : if ((flags & DEQUEUE_SLEEP)) {
1592 : unsigned int state;
1593 :
1594 : state = READ_ONCE(p->__state);
1595 : if (state & TASK_INTERRUPTIBLE)
1596 : __schedstat_set(p->stats.sleep_start,
1597 : rq_clock(rq_of_dl_rq(dl_rq)));
1598 :
1599 : if (state & TASK_UNINTERRUPTIBLE)
1600 : __schedstat_set(p->stats.block_start,
1601 : rq_clock(rq_of_dl_rq(dl_rq)));
1602 : }
1603 : }
1604 :
1605 0 : static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
1606 : {
1607 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1608 :
1609 0 : WARN_ON_ONCE(!RB_EMPTY_NODE(&dl_se->rb_node));
1610 :
1611 0 : rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less);
1612 :
1613 0 : inc_dl_tasks(dl_se, dl_rq);
1614 0 : }
1615 :
1616 0 : static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
1617 : {
1618 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1619 :
1620 0 : if (RB_EMPTY_NODE(&dl_se->rb_node))
1621 : return;
1622 :
1623 0 : rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
1624 :
1625 0 : RB_CLEAR_NODE(&dl_se->rb_node);
1626 :
1627 0 : dec_dl_tasks(dl_se, dl_rq);
1628 : }
1629 :
1630 : static void
1631 0 : enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
1632 : {
1633 0 : WARN_ON_ONCE(on_dl_rq(dl_se));
1634 :
1635 0 : update_stats_enqueue_dl(dl_rq_of_se(dl_se), dl_se, flags);
1636 :
1637 : /*
1638 : * If this is a wakeup or a new instance, the scheduling
1639 : * parameters of the task might need updating. Otherwise,
1640 : * we want a replenishment of its runtime.
1641 : */
1642 0 : if (flags & ENQUEUE_WAKEUP) {
1643 0 : task_contending(dl_se, flags);
1644 0 : update_dl_entity(dl_se);
1645 0 : } else if (flags & ENQUEUE_REPLENISH) {
1646 0 : replenish_dl_entity(dl_se);
1647 0 : } else if ((flags & ENQUEUE_RESTORE) &&
1648 0 : dl_time_before(dl_se->deadline,
1649 : rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) {
1650 0 : setup_new_dl_entity(dl_se);
1651 : }
1652 :
1653 0 : __enqueue_dl_entity(dl_se);
1654 0 : }
1655 :
1656 : static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
1657 : {
1658 0 : __dequeue_dl_entity(dl_se);
1659 : }
1660 :
1661 0 : static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1662 : {
1663 0 : if (is_dl_boosted(&p->dl)) {
1664 : /*
1665 : * Because of delays in the detection of the overrun of a
1666 : * thread's runtime, it might be the case that a thread
1667 : * goes to sleep in a rt mutex with negative runtime. As
1668 : * a consequence, the thread will be throttled.
1669 : *
1670 : * While waiting for the mutex, this thread can also be
1671 : * boosted via PI, resulting in a thread that is throttled
1672 : * and boosted at the same time.
1673 : *
1674 : * In this case, the boost overrides the throttle.
1675 : */
1676 0 : if (p->dl.dl_throttled) {
1677 : /*
1678 : * The replenish timer needs to be canceled. No
1679 : * problem if it fires concurrently: boosted threads
1680 : * are ignored in dl_task_timer().
1681 : */
1682 0 : hrtimer_try_to_cancel(&p->dl.dl_timer);
1683 0 : p->dl.dl_throttled = 0;
1684 : }
1685 0 : } else if (!dl_prio(p->normal_prio)) {
1686 : /*
1687 : * Special case in which we have a !SCHED_DEADLINE task that is going
1688 : * to be deboosted, but exceeds its runtime while doing so. No point in
1689 : * replenishing it, as it's going to return back to its original
1690 : * scheduling class after this. If it has been throttled, we need to
1691 : * clear the flag, otherwise the task may wake up as throttled after
1692 : * being boosted again with no means to replenish the runtime and clear
1693 : * the throttle.
1694 : */
1695 0 : p->dl.dl_throttled = 0;
1696 0 : if (!(flags & ENQUEUE_REPLENISH))
1697 0 : printk_deferred_once("sched: DL de-boosted task PID %d: REPLENISH flag missing\n",
1698 : task_pid_nr(p));
1699 :
1700 : return;
1701 : }
1702 :
1703 : /*
1704 : * Check if a constrained deadline task was activated
1705 : * after the deadline but before the next period.
1706 : * If that is the case, the task will be throttled and
1707 : * the replenishment timer will be set to the next period.
1708 : */
1709 0 : if (!p->dl.dl_throttled && !dl_is_implicit(&p->dl))
1710 0 : dl_check_constrained_dl(&p->dl);
1711 :
1712 0 : if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) {
1713 0 : add_rq_bw(&p->dl, &rq->dl);
1714 0 : add_running_bw(&p->dl, &rq->dl);
1715 : }
1716 :
1717 : /*
1718 : * If p is throttled, we do not enqueue it. In fact, if it exhausted
1719 : * its budget it needs a replenishment and, since it now is on
1720 : * its rq, the bandwidth timer callback (which clearly has not
1721 : * run yet) will take care of this.
1722 : * However, the active utilization does not depend on the fact
1723 : * that the task is on the runqueue or not (but depends on the
1724 : * task's state - in GRUB parlance, "inactive" vs "active contending").
1725 : * In other words, even if a task is throttled its utilization must
1726 : * be counted in the active utilization; hence, we need to call
1727 : * add_running_bw().
1728 : */
1729 0 : if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) {
1730 0 : if (flags & ENQUEUE_WAKEUP)
1731 0 : task_contending(&p->dl, flags);
1732 :
1733 : return;
1734 : }
1735 :
1736 : check_schedstat_required();
1737 0 : update_stats_wait_start_dl(dl_rq_of_se(&p->dl), &p->dl);
1738 :
1739 0 : enqueue_dl_entity(&p->dl, flags);
1740 :
1741 0 : if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1742 : enqueue_pushable_dl_task(rq, p);
1743 : }
1744 :
1745 : static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1746 : {
1747 0 : update_stats_dequeue_dl(&rq->dl, &p->dl, flags);
1748 0 : dequeue_dl_entity(&p->dl);
1749 0 : dequeue_pushable_dl_task(rq, p);
1750 : }
1751 :
1752 0 : static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1753 : {
1754 0 : update_curr_dl(rq);
1755 0 : __dequeue_task_dl(rq, p, flags);
1756 :
1757 0 : if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) {
1758 0 : sub_running_bw(&p->dl, &rq->dl);
1759 0 : sub_rq_bw(&p->dl, &rq->dl);
1760 : }
1761 :
1762 : /*
1763 : * This check allows to start the inactive timer (or to immediately
1764 : * decrease the active utilization, if needed) in two cases:
1765 : * when the task blocks and when it is terminating
1766 : * (p->state == TASK_DEAD). We can handle the two cases in the same
1767 : * way, because from GRUB's point of view the same thing is happening
1768 : * (the task moves from "active contending" to "active non contending"
1769 : * or "inactive")
1770 : */
1771 0 : if (flags & DEQUEUE_SLEEP)
1772 0 : task_non_contending(p);
1773 0 : }
1774 :
1775 : /*
1776 : * Yield task semantic for -deadline tasks is:
1777 : *
1778 : * get off from the CPU until our next instance, with
1779 : * a new runtime. This is of little use now, since we
1780 : * don't have a bandwidth reclaiming mechanism. Anyway,
1781 : * bandwidth reclaiming is planned for the future, and
1782 : * yield_task_dl will indicate that some spare budget
1783 : * is available for other task instances to use it.
1784 : */
1785 0 : static void yield_task_dl(struct rq *rq)
1786 : {
1787 : /*
1788 : * We make the task go to sleep until its current deadline by
1789 : * forcing its runtime to zero. This way, update_curr_dl() stops
1790 : * it and the bandwidth timer will wake it up and will give it
1791 : * new scheduling parameters (thanks to dl_yielded=1).
1792 : */
1793 0 : rq->curr->dl.dl_yielded = 1;
1794 :
1795 0 : update_rq_clock(rq);
1796 0 : update_curr_dl(rq);
1797 : /*
1798 : * Tell update_rq_clock() that we've just updated,
1799 : * so we don't do microscopic update in schedule()
1800 : * and double the fastpath cost.
1801 : */
1802 0 : rq_clock_skip_update(rq);
1803 0 : }
1804 :
1805 : #ifdef CONFIG_SMP
1806 :
1807 : static inline bool dl_task_is_earliest_deadline(struct task_struct *p,
1808 : struct rq *rq)
1809 : {
1810 : return (!rq->dl.dl_nr_running ||
1811 : dl_time_before(p->dl.deadline,
1812 : rq->dl.earliest_dl.curr));
1813 : }
1814 :
1815 : static int find_later_rq(struct task_struct *task);
1816 :
1817 : static int
1818 : select_task_rq_dl(struct task_struct *p, int cpu, int flags)
1819 : {
1820 : struct task_struct *curr;
1821 : bool select_rq;
1822 : struct rq *rq;
1823 :
1824 : if (!(flags & WF_TTWU))
1825 : goto out;
1826 :
1827 : rq = cpu_rq(cpu);
1828 :
1829 : rcu_read_lock();
1830 : curr = READ_ONCE(rq->curr); /* unlocked access */
1831 :
1832 : /*
1833 : * If we are dealing with a -deadline task, we must
1834 : * decide where to wake it up.
1835 : * If it has a later deadline and the current task
1836 : * on this rq can't move (provided the waking task
1837 : * can!) we prefer to send it somewhere else. On the
1838 : * other hand, if it has a shorter deadline, we
1839 : * try to make it stay here, it might be important.
1840 : */
1841 : select_rq = unlikely(dl_task(curr)) &&
1842 : (curr->nr_cpus_allowed < 2 ||
1843 : !dl_entity_preempt(&p->dl, &curr->dl)) &&
1844 : p->nr_cpus_allowed > 1;
1845 :
1846 : /*
1847 : * Take the capacity of the CPU into account to
1848 : * ensure it fits the requirement of the task.
1849 : */
1850 : if (sched_asym_cpucap_active())
1851 : select_rq |= !dl_task_fits_capacity(p, cpu);
1852 :
1853 : if (select_rq) {
1854 : int target = find_later_rq(p);
1855 :
1856 : if (target != -1 &&
1857 : dl_task_is_earliest_deadline(p, cpu_rq(target)))
1858 : cpu = target;
1859 : }
1860 : rcu_read_unlock();
1861 :
1862 : out:
1863 : return cpu;
1864 : }
1865 :
1866 : static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused)
1867 : {
1868 : struct rq_flags rf;
1869 : struct rq *rq;
1870 :
1871 : if (READ_ONCE(p->__state) != TASK_WAKING)
1872 : return;
1873 :
1874 : rq = task_rq(p);
1875 : /*
1876 : * Since p->state == TASK_WAKING, set_task_cpu() has been called
1877 : * from try_to_wake_up(). Hence, p->pi_lock is locked, but
1878 : * rq->lock is not... So, lock it
1879 : */
1880 : rq_lock(rq, &rf);
1881 : if (p->dl.dl_non_contending) {
1882 : update_rq_clock(rq);
1883 : sub_running_bw(&p->dl, &rq->dl);
1884 : p->dl.dl_non_contending = 0;
1885 : /*
1886 : * If the timer handler is currently running and the
1887 : * timer cannot be canceled, inactive_task_timer()
1888 : * will see that dl_not_contending is not set, and
1889 : * will not touch the rq's active utilization,
1890 : * so we are still safe.
1891 : */
1892 : if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
1893 : put_task_struct(p);
1894 : }
1895 : sub_rq_bw(&p->dl, &rq->dl);
1896 : rq_unlock(rq, &rf);
1897 : }
1898 :
1899 : static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1900 : {
1901 : /*
1902 : * Current can't be migrated, useless to reschedule,
1903 : * let's hope p can move out.
1904 : */
1905 : if (rq->curr->nr_cpus_allowed == 1 ||
1906 : !cpudl_find(&rq->rd->cpudl, rq->curr, NULL))
1907 : return;
1908 :
1909 : /*
1910 : * p is migratable, so let's not schedule it and
1911 : * see if it is pushed or pulled somewhere else.
1912 : */
1913 : if (p->nr_cpus_allowed != 1 &&
1914 : cpudl_find(&rq->rd->cpudl, p, NULL))
1915 : return;
1916 :
1917 : resched_curr(rq);
1918 : }
1919 :
1920 : static int balance_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
1921 : {
1922 : if (!on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) {
1923 : /*
1924 : * This is OK, because current is on_cpu, which avoids it being
1925 : * picked for load-balance and preemption/IRQs are still
1926 : * disabled avoiding further scheduler activity on it and we've
1927 : * not yet started the picking loop.
1928 : */
1929 : rq_unpin_lock(rq, rf);
1930 : pull_dl_task(rq);
1931 : rq_repin_lock(rq, rf);
1932 : }
1933 :
1934 : return sched_stop_runnable(rq) || sched_dl_runnable(rq);
1935 : }
1936 : #endif /* CONFIG_SMP */
1937 :
1938 : /*
1939 : * Only called when both the current and waking task are -deadline
1940 : * tasks.
1941 : */
1942 0 : static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
1943 : int flags)
1944 : {
1945 0 : if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
1946 0 : resched_curr(rq);
1947 0 : return;
1948 : }
1949 :
1950 : #ifdef CONFIG_SMP
1951 : /*
1952 : * In the unlikely case current and p have the same deadline
1953 : * let us try to decide what's the best thing to do...
1954 : */
1955 : if ((p->dl.deadline == rq->curr->dl.deadline) &&
1956 : !test_tsk_need_resched(rq->curr))
1957 : check_preempt_equal_dl(rq, p);
1958 : #endif /* CONFIG_SMP */
1959 : }
1960 :
1961 : #ifdef CONFIG_SCHED_HRTICK
1962 : static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1963 : {
1964 : hrtick_start(rq, p->dl.runtime);
1965 : }
1966 : #else /* !CONFIG_SCHED_HRTICK */
1967 : static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1968 : {
1969 : }
1970 : #endif
1971 :
1972 0 : static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first)
1973 : {
1974 0 : struct sched_dl_entity *dl_se = &p->dl;
1975 0 : struct dl_rq *dl_rq = &rq->dl;
1976 :
1977 0 : p->se.exec_start = rq_clock_task(rq);
1978 0 : if (on_dl_rq(&p->dl))
1979 : update_stats_wait_end_dl(dl_rq, dl_se);
1980 :
1981 : /* You can't push away the running task */
1982 0 : dequeue_pushable_dl_task(rq, p);
1983 :
1984 : if (!first)
1985 : return;
1986 :
1987 : if (hrtick_enabled_dl(rq))
1988 : start_hrtick_dl(rq, p);
1989 :
1990 : if (rq->curr->sched_class != &dl_sched_class)
1991 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
1992 :
1993 : deadline_queue_push_tasks(rq);
1994 : }
1995 :
1996 : static struct sched_dl_entity *pick_next_dl_entity(struct dl_rq *dl_rq)
1997 : {
1998 0 : struct rb_node *left = rb_first_cached(&dl_rq->root);
1999 :
2000 0 : if (!left)
2001 : return NULL;
2002 :
2003 0 : return __node_2_dle(left);
2004 : }
2005 :
2006 0 : static struct task_struct *pick_task_dl(struct rq *rq)
2007 : {
2008 : struct sched_dl_entity *dl_se;
2009 0 : struct dl_rq *dl_rq = &rq->dl;
2010 : struct task_struct *p;
2011 :
2012 0 : if (!sched_dl_runnable(rq))
2013 : return NULL;
2014 :
2015 0 : dl_se = pick_next_dl_entity(dl_rq);
2016 0 : WARN_ON_ONCE(!dl_se);
2017 0 : p = dl_task_of(dl_se);
2018 :
2019 0 : return p;
2020 : }
2021 :
2022 0 : static struct task_struct *pick_next_task_dl(struct rq *rq)
2023 : {
2024 : struct task_struct *p;
2025 :
2026 0 : p = pick_task_dl(rq);
2027 0 : if (p)
2028 : set_next_task_dl(rq, p, true);
2029 :
2030 0 : return p;
2031 : }
2032 :
2033 0 : static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
2034 : {
2035 0 : struct sched_dl_entity *dl_se = &p->dl;
2036 0 : struct dl_rq *dl_rq = &rq->dl;
2037 :
2038 0 : if (on_dl_rq(&p->dl))
2039 : update_stats_wait_start_dl(dl_rq, dl_se);
2040 :
2041 0 : update_curr_dl(rq);
2042 :
2043 0 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2044 0 : if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
2045 : enqueue_pushable_dl_task(rq, p);
2046 0 : }
2047 :
2048 : /*
2049 : * scheduler tick hitting a task of our scheduling class.
2050 : *
2051 : * NOTE: This function can be called remotely by the tick offload that
2052 : * goes along full dynticks. Therefore no local assumption can be made
2053 : * and everything must be accessed through the @rq and @curr passed in
2054 : * parameters.
2055 : */
2056 0 : static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
2057 : {
2058 0 : update_curr_dl(rq);
2059 :
2060 0 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2061 : /*
2062 : * Even when we have runtime, update_curr_dl() might have resulted in us
2063 : * not being the leftmost task anymore. In that case NEED_RESCHED will
2064 : * be set and schedule() will start a new hrtick for the next task.
2065 : */
2066 0 : if (hrtick_enabled_dl(rq) && queued && p->dl.runtime > 0 &&
2067 : is_leftmost(p, &rq->dl))
2068 : start_hrtick_dl(rq, p);
2069 0 : }
2070 :
2071 0 : static void task_fork_dl(struct task_struct *p)
2072 : {
2073 : /*
2074 : * SCHED_DEADLINE tasks cannot fork and this is achieved through
2075 : * sched_fork()
2076 : */
2077 0 : }
2078 :
2079 : #ifdef CONFIG_SMP
2080 :
2081 : /* Only try algorithms three times */
2082 : #define DL_MAX_TRIES 3
2083 :
2084 : static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
2085 : {
2086 : if (!task_on_cpu(rq, p) &&
2087 : cpumask_test_cpu(cpu, &p->cpus_mask))
2088 : return 1;
2089 : return 0;
2090 : }
2091 :
2092 : /*
2093 : * Return the earliest pushable rq's task, which is suitable to be executed
2094 : * on the CPU, NULL otherwise:
2095 : */
2096 : static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
2097 : {
2098 : struct task_struct *p = NULL;
2099 : struct rb_node *next_node;
2100 :
2101 : if (!has_pushable_dl_tasks(rq))
2102 : return NULL;
2103 :
2104 : next_node = rb_first_cached(&rq->dl.pushable_dl_tasks_root);
2105 :
2106 : next_node:
2107 : if (next_node) {
2108 : p = __node_2_pdl(next_node);
2109 :
2110 : if (pick_dl_task(rq, p, cpu))
2111 : return p;
2112 :
2113 : next_node = rb_next(next_node);
2114 : goto next_node;
2115 : }
2116 :
2117 : return NULL;
2118 : }
2119 :
2120 : static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
2121 :
2122 : static int find_later_rq(struct task_struct *task)
2123 : {
2124 : struct sched_domain *sd;
2125 : struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
2126 : int this_cpu = smp_processor_id();
2127 : int cpu = task_cpu(task);
2128 :
2129 : /* Make sure the mask is initialized first */
2130 : if (unlikely(!later_mask))
2131 : return -1;
2132 :
2133 : if (task->nr_cpus_allowed == 1)
2134 : return -1;
2135 :
2136 : /*
2137 : * We have to consider system topology and task affinity
2138 : * first, then we can look for a suitable CPU.
2139 : */
2140 : if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask))
2141 : return -1;
2142 :
2143 : /*
2144 : * If we are here, some targets have been found, including
2145 : * the most suitable which is, among the runqueues where the
2146 : * current tasks have later deadlines than the task's one, the
2147 : * rq with the latest possible one.
2148 : *
2149 : * Now we check how well this matches with task's
2150 : * affinity and system topology.
2151 : *
2152 : * The last CPU where the task run is our first
2153 : * guess, since it is most likely cache-hot there.
2154 : */
2155 : if (cpumask_test_cpu(cpu, later_mask))
2156 : return cpu;
2157 : /*
2158 : * Check if this_cpu is to be skipped (i.e., it is
2159 : * not in the mask) or not.
2160 : */
2161 : if (!cpumask_test_cpu(this_cpu, later_mask))
2162 : this_cpu = -1;
2163 :
2164 : rcu_read_lock();
2165 : for_each_domain(cpu, sd) {
2166 : if (sd->flags & SD_WAKE_AFFINE) {
2167 : int best_cpu;
2168 :
2169 : /*
2170 : * If possible, preempting this_cpu is
2171 : * cheaper than migrating.
2172 : */
2173 : if (this_cpu != -1 &&
2174 : cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
2175 : rcu_read_unlock();
2176 : return this_cpu;
2177 : }
2178 :
2179 : best_cpu = cpumask_any_and_distribute(later_mask,
2180 : sched_domain_span(sd));
2181 : /*
2182 : * Last chance: if a CPU being in both later_mask
2183 : * and current sd span is valid, that becomes our
2184 : * choice. Of course, the latest possible CPU is
2185 : * already under consideration through later_mask.
2186 : */
2187 : if (best_cpu < nr_cpu_ids) {
2188 : rcu_read_unlock();
2189 : return best_cpu;
2190 : }
2191 : }
2192 : }
2193 : rcu_read_unlock();
2194 :
2195 : /*
2196 : * At this point, all our guesses failed, we just return
2197 : * 'something', and let the caller sort the things out.
2198 : */
2199 : if (this_cpu != -1)
2200 : return this_cpu;
2201 :
2202 : cpu = cpumask_any_distribute(later_mask);
2203 : if (cpu < nr_cpu_ids)
2204 : return cpu;
2205 :
2206 : return -1;
2207 : }
2208 :
2209 : /* Locks the rq it finds */
2210 : static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
2211 : {
2212 : struct rq *later_rq = NULL;
2213 : int tries;
2214 : int cpu;
2215 :
2216 : for (tries = 0; tries < DL_MAX_TRIES; tries++) {
2217 : cpu = find_later_rq(task);
2218 :
2219 : if ((cpu == -1) || (cpu == rq->cpu))
2220 : break;
2221 :
2222 : later_rq = cpu_rq(cpu);
2223 :
2224 : if (!dl_task_is_earliest_deadline(task, later_rq)) {
2225 : /*
2226 : * Target rq has tasks of equal or earlier deadline,
2227 : * retrying does not release any lock and is unlikely
2228 : * to yield a different result.
2229 : */
2230 : later_rq = NULL;
2231 : break;
2232 : }
2233 :
2234 : /* Retry if something changed. */
2235 : if (double_lock_balance(rq, later_rq)) {
2236 : if (unlikely(task_rq(task) != rq ||
2237 : !cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) ||
2238 : task_on_cpu(rq, task) ||
2239 : !dl_task(task) ||
2240 : is_migration_disabled(task) ||
2241 : !task_on_rq_queued(task))) {
2242 : double_unlock_balance(rq, later_rq);
2243 : later_rq = NULL;
2244 : break;
2245 : }
2246 : }
2247 :
2248 : /*
2249 : * If the rq we found has no -deadline task, or
2250 : * its earliest one has a later deadline than our
2251 : * task, the rq is a good one.
2252 : */
2253 : if (dl_task_is_earliest_deadline(task, later_rq))
2254 : break;
2255 :
2256 : /* Otherwise we try again. */
2257 : double_unlock_balance(rq, later_rq);
2258 : later_rq = NULL;
2259 : }
2260 :
2261 : return later_rq;
2262 : }
2263 :
2264 : static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
2265 : {
2266 : struct task_struct *p;
2267 :
2268 : if (!has_pushable_dl_tasks(rq))
2269 : return NULL;
2270 :
2271 : p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root));
2272 :
2273 : WARN_ON_ONCE(rq->cpu != task_cpu(p));
2274 : WARN_ON_ONCE(task_current(rq, p));
2275 : WARN_ON_ONCE(p->nr_cpus_allowed <= 1);
2276 :
2277 : WARN_ON_ONCE(!task_on_rq_queued(p));
2278 : WARN_ON_ONCE(!dl_task(p));
2279 :
2280 : return p;
2281 : }
2282 :
2283 : /*
2284 : * See if the non running -deadline tasks on this rq
2285 : * can be sent to some other CPU where they can preempt
2286 : * and start executing.
2287 : */
2288 : static int push_dl_task(struct rq *rq)
2289 : {
2290 : struct task_struct *next_task;
2291 : struct rq *later_rq;
2292 : int ret = 0;
2293 :
2294 : if (!rq->dl.overloaded)
2295 : return 0;
2296 :
2297 : next_task = pick_next_pushable_dl_task(rq);
2298 : if (!next_task)
2299 : return 0;
2300 :
2301 : retry:
2302 : /*
2303 : * If next_task preempts rq->curr, and rq->curr
2304 : * can move away, it makes sense to just reschedule
2305 : * without going further in pushing next_task.
2306 : */
2307 : if (dl_task(rq->curr) &&
2308 : dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
2309 : rq->curr->nr_cpus_allowed > 1) {
2310 : resched_curr(rq);
2311 : return 0;
2312 : }
2313 :
2314 : if (is_migration_disabled(next_task))
2315 : return 0;
2316 :
2317 : if (WARN_ON(next_task == rq->curr))
2318 : return 0;
2319 :
2320 : /* We might release rq lock */
2321 : get_task_struct(next_task);
2322 :
2323 : /* Will lock the rq it'll find */
2324 : later_rq = find_lock_later_rq(next_task, rq);
2325 : if (!later_rq) {
2326 : struct task_struct *task;
2327 :
2328 : /*
2329 : * We must check all this again, since
2330 : * find_lock_later_rq releases rq->lock and it is
2331 : * then possible that next_task has migrated.
2332 : */
2333 : task = pick_next_pushable_dl_task(rq);
2334 : if (task == next_task) {
2335 : /*
2336 : * The task is still there. We don't try
2337 : * again, some other CPU will pull it when ready.
2338 : */
2339 : goto out;
2340 : }
2341 :
2342 : if (!task)
2343 : /* No more tasks */
2344 : goto out;
2345 :
2346 : put_task_struct(next_task);
2347 : next_task = task;
2348 : goto retry;
2349 : }
2350 :
2351 : deactivate_task(rq, next_task, 0);
2352 : set_task_cpu(next_task, later_rq->cpu);
2353 : activate_task(later_rq, next_task, 0);
2354 : ret = 1;
2355 :
2356 : resched_curr(later_rq);
2357 :
2358 : double_unlock_balance(rq, later_rq);
2359 :
2360 : out:
2361 : put_task_struct(next_task);
2362 :
2363 : return ret;
2364 : }
2365 :
2366 : static void push_dl_tasks(struct rq *rq)
2367 : {
2368 : /* push_dl_task() will return true if it moved a -deadline task */
2369 : while (push_dl_task(rq))
2370 : ;
2371 : }
2372 :
2373 : static void pull_dl_task(struct rq *this_rq)
2374 : {
2375 : int this_cpu = this_rq->cpu, cpu;
2376 : struct task_struct *p, *push_task;
2377 : bool resched = false;
2378 : struct rq *src_rq;
2379 : u64 dmin = LONG_MAX;
2380 :
2381 : if (likely(!dl_overloaded(this_rq)))
2382 : return;
2383 :
2384 : /*
2385 : * Match the barrier from dl_set_overloaded; this guarantees that if we
2386 : * see overloaded we must also see the dlo_mask bit.
2387 : */
2388 : smp_rmb();
2389 :
2390 : for_each_cpu(cpu, this_rq->rd->dlo_mask) {
2391 : if (this_cpu == cpu)
2392 : continue;
2393 :
2394 : src_rq = cpu_rq(cpu);
2395 :
2396 : /*
2397 : * It looks racy, abd it is! However, as in sched_rt.c,
2398 : * we are fine with this.
2399 : */
2400 : if (this_rq->dl.dl_nr_running &&
2401 : dl_time_before(this_rq->dl.earliest_dl.curr,
2402 : src_rq->dl.earliest_dl.next))
2403 : continue;
2404 :
2405 : /* Might drop this_rq->lock */
2406 : push_task = NULL;
2407 : double_lock_balance(this_rq, src_rq);
2408 :
2409 : /*
2410 : * If there are no more pullable tasks on the
2411 : * rq, we're done with it.
2412 : */
2413 : if (src_rq->dl.dl_nr_running <= 1)
2414 : goto skip;
2415 :
2416 : p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
2417 :
2418 : /*
2419 : * We found a task to be pulled if:
2420 : * - it preempts our current (if there's one),
2421 : * - it will preempt the last one we pulled (if any).
2422 : */
2423 : if (p && dl_time_before(p->dl.deadline, dmin) &&
2424 : dl_task_is_earliest_deadline(p, this_rq)) {
2425 : WARN_ON(p == src_rq->curr);
2426 : WARN_ON(!task_on_rq_queued(p));
2427 :
2428 : /*
2429 : * Then we pull iff p has actually an earlier
2430 : * deadline than the current task of its runqueue.
2431 : */
2432 : if (dl_time_before(p->dl.deadline,
2433 : src_rq->curr->dl.deadline))
2434 : goto skip;
2435 :
2436 : if (is_migration_disabled(p)) {
2437 : push_task = get_push_task(src_rq);
2438 : } else {
2439 : deactivate_task(src_rq, p, 0);
2440 : set_task_cpu(p, this_cpu);
2441 : activate_task(this_rq, p, 0);
2442 : dmin = p->dl.deadline;
2443 : resched = true;
2444 : }
2445 :
2446 : /* Is there any other task even earlier? */
2447 : }
2448 : skip:
2449 : double_unlock_balance(this_rq, src_rq);
2450 :
2451 : if (push_task) {
2452 : raw_spin_rq_unlock(this_rq);
2453 : stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
2454 : push_task, &src_rq->push_work);
2455 : raw_spin_rq_lock(this_rq);
2456 : }
2457 : }
2458 :
2459 : if (resched)
2460 : resched_curr(this_rq);
2461 : }
2462 :
2463 : /*
2464 : * Since the task is not running and a reschedule is not going to happen
2465 : * anytime soon on its runqueue, we try pushing it away now.
2466 : */
2467 : static void task_woken_dl(struct rq *rq, struct task_struct *p)
2468 : {
2469 : if (!task_on_cpu(rq, p) &&
2470 : !test_tsk_need_resched(rq->curr) &&
2471 : p->nr_cpus_allowed > 1 &&
2472 : dl_task(rq->curr) &&
2473 : (rq->curr->nr_cpus_allowed < 2 ||
2474 : !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
2475 : push_dl_tasks(rq);
2476 : }
2477 : }
2478 :
2479 : static void set_cpus_allowed_dl(struct task_struct *p,
2480 : struct affinity_context *ctx)
2481 : {
2482 : struct root_domain *src_rd;
2483 : struct rq *rq;
2484 :
2485 : WARN_ON_ONCE(!dl_task(p));
2486 :
2487 : rq = task_rq(p);
2488 : src_rd = rq->rd;
2489 : /*
2490 : * Migrating a SCHED_DEADLINE task between exclusive
2491 : * cpusets (different root_domains) entails a bandwidth
2492 : * update. We already made space for us in the destination
2493 : * domain (see cpuset_can_attach()).
2494 : */
2495 : if (!cpumask_intersects(src_rd->span, ctx->new_mask)) {
2496 : struct dl_bw *src_dl_b;
2497 :
2498 : src_dl_b = dl_bw_of(cpu_of(rq));
2499 : /*
2500 : * We now free resources of the root_domain we are migrating
2501 : * off. In the worst case, sched_setattr() may temporary fail
2502 : * until we complete the update.
2503 : */
2504 : raw_spin_lock(&src_dl_b->lock);
2505 : __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
2506 : raw_spin_unlock(&src_dl_b->lock);
2507 : }
2508 :
2509 : set_cpus_allowed_common(p, ctx);
2510 : }
2511 :
2512 : /* Assumes rq->lock is held */
2513 : static void rq_online_dl(struct rq *rq)
2514 : {
2515 : if (rq->dl.overloaded)
2516 : dl_set_overload(rq);
2517 :
2518 : cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
2519 : if (rq->dl.dl_nr_running > 0)
2520 : cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr);
2521 : }
2522 :
2523 : /* Assumes rq->lock is held */
2524 : static void rq_offline_dl(struct rq *rq)
2525 : {
2526 : if (rq->dl.overloaded)
2527 : dl_clear_overload(rq);
2528 :
2529 : cpudl_clear(&rq->rd->cpudl, rq->cpu);
2530 : cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
2531 : }
2532 :
2533 : void __init init_sched_dl_class(void)
2534 : {
2535 : unsigned int i;
2536 :
2537 : for_each_possible_cpu(i)
2538 : zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
2539 : GFP_KERNEL, cpu_to_node(i));
2540 : }
2541 :
2542 : void dl_add_task_root_domain(struct task_struct *p)
2543 : {
2544 : struct rq_flags rf;
2545 : struct rq *rq;
2546 : struct dl_bw *dl_b;
2547 :
2548 : raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2549 : if (!dl_task(p)) {
2550 : raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
2551 : return;
2552 : }
2553 :
2554 : rq = __task_rq_lock(p, &rf);
2555 :
2556 : dl_b = &rq->rd->dl_bw;
2557 : raw_spin_lock(&dl_b->lock);
2558 :
2559 : __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
2560 :
2561 : raw_spin_unlock(&dl_b->lock);
2562 :
2563 : task_rq_unlock(rq, p, &rf);
2564 : }
2565 :
2566 : void dl_clear_root_domain(struct root_domain *rd)
2567 : {
2568 : unsigned long flags;
2569 :
2570 : raw_spin_lock_irqsave(&rd->dl_bw.lock, flags);
2571 : rd->dl_bw.total_bw = 0;
2572 : raw_spin_unlock_irqrestore(&rd->dl_bw.lock, flags);
2573 : }
2574 :
2575 : #endif /* CONFIG_SMP */
2576 :
2577 0 : static void switched_from_dl(struct rq *rq, struct task_struct *p)
2578 : {
2579 : /*
2580 : * task_non_contending() can start the "inactive timer" (if the 0-lag
2581 : * time is in the future). If the task switches back to dl before
2582 : * the "inactive timer" fires, it can continue to consume its current
2583 : * runtime using its current deadline. If it stays outside of
2584 : * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer()
2585 : * will reset the task parameters.
2586 : */
2587 0 : if (task_on_rq_queued(p) && p->dl.dl_runtime)
2588 0 : task_non_contending(p);
2589 :
2590 : /*
2591 : * In case a task is setscheduled out from SCHED_DEADLINE we need to
2592 : * keep track of that on its cpuset (for correct bandwidth tracking).
2593 : */
2594 0 : dec_dl_tasks_cs(p);
2595 :
2596 0 : if (!task_on_rq_queued(p)) {
2597 : /*
2598 : * Inactive timer is armed. However, p is leaving DEADLINE and
2599 : * might migrate away from this rq while continuing to run on
2600 : * some other class. We need to remove its contribution from
2601 : * this rq running_bw now, or sub_rq_bw (below) will complain.
2602 : */
2603 0 : if (p->dl.dl_non_contending)
2604 0 : sub_running_bw(&p->dl, &rq->dl);
2605 0 : sub_rq_bw(&p->dl, &rq->dl);
2606 : }
2607 :
2608 : /*
2609 : * We cannot use inactive_task_timer() to invoke sub_running_bw()
2610 : * at the 0-lag time, because the task could have been migrated
2611 : * while SCHED_OTHER in the meanwhile.
2612 : */
2613 0 : if (p->dl.dl_non_contending)
2614 0 : p->dl.dl_non_contending = 0;
2615 :
2616 : /*
2617 : * Since this might be the only -deadline task on the rq,
2618 : * this is the right place to try to pull some other one
2619 : * from an overloaded CPU, if any.
2620 : */
2621 0 : if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
2622 : return;
2623 :
2624 : deadline_queue_pull_task(rq);
2625 : }
2626 :
2627 : /*
2628 : * When switching to -deadline, we may overload the rq, then
2629 : * we try to push someone off, if possible.
2630 : */
2631 0 : static void switched_to_dl(struct rq *rq, struct task_struct *p)
2632 : {
2633 0 : if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
2634 0 : put_task_struct(p);
2635 :
2636 : /*
2637 : * In case a task is setscheduled to SCHED_DEADLINE we need to keep
2638 : * track of that on its cpuset (for correct bandwidth tracking).
2639 : */
2640 0 : inc_dl_tasks_cs(p);
2641 :
2642 : /* If p is not queued we will update its parameters at next wakeup. */
2643 0 : if (!task_on_rq_queued(p)) {
2644 0 : add_rq_bw(&p->dl, &rq->dl);
2645 :
2646 : return;
2647 : }
2648 :
2649 0 : if (rq->curr != p) {
2650 : #ifdef CONFIG_SMP
2651 : if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
2652 : deadline_queue_push_tasks(rq);
2653 : #endif
2654 0 : if (dl_task(rq->curr))
2655 : check_preempt_curr_dl(rq, p, 0);
2656 : else
2657 0 : resched_curr(rq);
2658 : } else {
2659 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
2660 : }
2661 : }
2662 :
2663 : /*
2664 : * If the scheduling parameters of a -deadline task changed,
2665 : * a push or pull operation might be needed.
2666 : */
2667 0 : static void prio_changed_dl(struct rq *rq, struct task_struct *p,
2668 : int oldprio)
2669 : {
2670 0 : if (!task_on_rq_queued(p))
2671 : return;
2672 :
2673 : #ifdef CONFIG_SMP
2674 : /*
2675 : * This might be too much, but unfortunately
2676 : * we don't have the old deadline value, and
2677 : * we can't argue if the task is increasing
2678 : * or lowering its prio, so...
2679 : */
2680 : if (!rq->dl.overloaded)
2681 : deadline_queue_pull_task(rq);
2682 :
2683 : if (task_current(rq, p)) {
2684 : /*
2685 : * If we now have a earlier deadline task than p,
2686 : * then reschedule, provided p is still on this
2687 : * runqueue.
2688 : */
2689 : if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline))
2690 : resched_curr(rq);
2691 : } else {
2692 : /*
2693 : * Current may not be deadline in case p was throttled but we
2694 : * have just replenished it (e.g. rt_mutex_setprio()).
2695 : *
2696 : * Otherwise, if p was given an earlier deadline, reschedule.
2697 : */
2698 : if (!dl_task(rq->curr) ||
2699 : dl_time_before(p->dl.deadline, rq->curr->dl.deadline))
2700 : resched_curr(rq);
2701 : }
2702 : #else
2703 : /*
2704 : * We don't know if p has a earlier or later deadline, so let's blindly
2705 : * set a (maybe not needed) rescheduling point.
2706 : */
2707 0 : resched_curr(rq);
2708 : #endif
2709 : }
2710 :
2711 : #ifdef CONFIG_SCHED_CORE
2712 : static int task_is_throttled_dl(struct task_struct *p, int cpu)
2713 : {
2714 : return p->dl.dl_throttled;
2715 : }
2716 : #endif
2717 :
2718 : DEFINE_SCHED_CLASS(dl) = {
2719 :
2720 : .enqueue_task = enqueue_task_dl,
2721 : .dequeue_task = dequeue_task_dl,
2722 : .yield_task = yield_task_dl,
2723 :
2724 : .check_preempt_curr = check_preempt_curr_dl,
2725 :
2726 : .pick_next_task = pick_next_task_dl,
2727 : .put_prev_task = put_prev_task_dl,
2728 : .set_next_task = set_next_task_dl,
2729 :
2730 : #ifdef CONFIG_SMP
2731 : .balance = balance_dl,
2732 : .pick_task = pick_task_dl,
2733 : .select_task_rq = select_task_rq_dl,
2734 : .migrate_task_rq = migrate_task_rq_dl,
2735 : .set_cpus_allowed = set_cpus_allowed_dl,
2736 : .rq_online = rq_online_dl,
2737 : .rq_offline = rq_offline_dl,
2738 : .task_woken = task_woken_dl,
2739 : .find_lock_rq = find_lock_later_rq,
2740 : #endif
2741 :
2742 : .task_tick = task_tick_dl,
2743 : .task_fork = task_fork_dl,
2744 :
2745 : .prio_changed = prio_changed_dl,
2746 : .switched_from = switched_from_dl,
2747 : .switched_to = switched_to_dl,
2748 :
2749 : .update_curr = update_curr_dl,
2750 : #ifdef CONFIG_SCHED_CORE
2751 : .task_is_throttled = task_is_throttled_dl,
2752 : #endif
2753 : };
2754 :
2755 : /* Used for dl_bw check and update, used under sched_rt_handler()::mutex */
2756 : static u64 dl_generation;
2757 :
2758 0 : int sched_dl_global_validate(void)
2759 : {
2760 0 : u64 runtime = global_rt_runtime();
2761 0 : u64 period = global_rt_period();
2762 0 : u64 new_bw = to_ratio(period, runtime);
2763 0 : u64 gen = ++dl_generation;
2764 : struct dl_bw *dl_b;
2765 0 : int cpu, cpus, ret = 0;
2766 : unsigned long flags;
2767 :
2768 : /*
2769 : * Here we want to check the bandwidth not being set to some
2770 : * value smaller than the currently allocated bandwidth in
2771 : * any of the root_domains.
2772 : */
2773 0 : for_each_possible_cpu(cpu) {
2774 : rcu_read_lock_sched();
2775 :
2776 0 : if (dl_bw_visited(cpu, gen))
2777 : goto next;
2778 :
2779 0 : dl_b = dl_bw_of(cpu);
2780 0 : cpus = dl_bw_cpus(cpu);
2781 :
2782 0 : raw_spin_lock_irqsave(&dl_b->lock, flags);
2783 0 : if (new_bw * cpus < dl_b->total_bw)
2784 0 : ret = -EBUSY;
2785 0 : raw_spin_unlock_irqrestore(&dl_b->lock, flags);
2786 :
2787 : next:
2788 : rcu_read_unlock_sched();
2789 :
2790 0 : if (ret)
2791 : break;
2792 : }
2793 :
2794 0 : return ret;
2795 : }
2796 :
2797 1 : static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
2798 : {
2799 1 : if (global_rt_runtime() == RUNTIME_INF) {
2800 0 : dl_rq->bw_ratio = 1 << RATIO_SHIFT;
2801 0 : dl_rq->max_bw = dl_rq->extra_bw = 1 << BW_SHIFT;
2802 : } else {
2803 2 : dl_rq->bw_ratio = to_ratio(global_rt_runtime(),
2804 1 : global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT);
2805 1 : dl_rq->max_bw = dl_rq->extra_bw =
2806 1 : to_ratio(global_rt_period(), global_rt_runtime());
2807 : }
2808 1 : }
2809 :
2810 0 : void sched_dl_do_global(void)
2811 : {
2812 0 : u64 new_bw = -1;
2813 0 : u64 gen = ++dl_generation;
2814 : struct dl_bw *dl_b;
2815 : int cpu;
2816 : unsigned long flags;
2817 :
2818 0 : if (global_rt_runtime() != RUNTIME_INF)
2819 0 : new_bw = to_ratio(global_rt_period(), global_rt_runtime());
2820 :
2821 0 : for_each_possible_cpu(cpu) {
2822 : rcu_read_lock_sched();
2823 :
2824 0 : if (dl_bw_visited(cpu, gen)) {
2825 : rcu_read_unlock_sched();
2826 : continue;
2827 : }
2828 :
2829 0 : dl_b = dl_bw_of(cpu);
2830 :
2831 0 : raw_spin_lock_irqsave(&dl_b->lock, flags);
2832 0 : dl_b->bw = new_bw;
2833 0 : raw_spin_unlock_irqrestore(&dl_b->lock, flags);
2834 :
2835 : rcu_read_unlock_sched();
2836 0 : init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl);
2837 : }
2838 0 : }
2839 :
2840 : /*
2841 : * We must be sure that accepting a new task (or allowing changing the
2842 : * parameters of an existing one) is consistent with the bandwidth
2843 : * constraints. If yes, this function also accordingly updates the currently
2844 : * allocated bandwidth to reflect the new situation.
2845 : *
2846 : * This function is called while holding p's rq->lock.
2847 : */
2848 0 : int sched_dl_overflow(struct task_struct *p, int policy,
2849 : const struct sched_attr *attr)
2850 : {
2851 0 : u64 period = attr->sched_period ?: attr->sched_deadline;
2852 0 : u64 runtime = attr->sched_runtime;
2853 0 : u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2854 0 : int cpus, err = -1, cpu = task_cpu(p);
2855 0 : struct dl_bw *dl_b = dl_bw_of(cpu);
2856 : unsigned long cap;
2857 :
2858 0 : if (attr->sched_flags & SCHED_FLAG_SUGOV)
2859 : return 0;
2860 :
2861 : /* !deadline task may carry old deadline bandwidth */
2862 0 : if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
2863 : return 0;
2864 :
2865 : /*
2866 : * Either if a task, enters, leave, or stays -deadline but changes
2867 : * its parameters, we may need to update accordingly the total
2868 : * allocated bandwidth of the container.
2869 : */
2870 0 : raw_spin_lock(&dl_b->lock);
2871 0 : cpus = dl_bw_cpus(cpu);
2872 0 : cap = dl_bw_capacity(cpu);
2873 :
2874 0 : if (dl_policy(policy) && !task_has_dl_policy(p) &&
2875 0 : !__dl_overflow(dl_b, cap, 0, new_bw)) {
2876 0 : if (hrtimer_active(&p->dl.inactive_timer))
2877 0 : __dl_sub(dl_b, p->dl.dl_bw, cpus);
2878 0 : __dl_add(dl_b, new_bw, cpus);
2879 0 : err = 0;
2880 0 : } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2881 0 : !__dl_overflow(dl_b, cap, p->dl.dl_bw, new_bw)) {
2882 : /*
2883 : * XXX this is slightly incorrect: when the task
2884 : * utilization decreases, we should delay the total
2885 : * utilization change until the task's 0-lag point.
2886 : * But this would require to set the task's "inactive
2887 : * timer" when the task is not inactive.
2888 : */
2889 0 : __dl_sub(dl_b, p->dl.dl_bw, cpus);
2890 0 : __dl_add(dl_b, new_bw, cpus);
2891 0 : dl_change_utilization(p, new_bw);
2892 0 : err = 0;
2893 0 : } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2894 : /*
2895 : * Do not decrease the total deadline utilization here,
2896 : * switched_from_dl() will take care to do it at the correct
2897 : * (0-lag) time.
2898 : */
2899 0 : err = 0;
2900 : }
2901 0 : raw_spin_unlock(&dl_b->lock);
2902 :
2903 0 : return err;
2904 : }
2905 :
2906 : /*
2907 : * This function initializes the sched_dl_entity of a newly becoming
2908 : * SCHED_DEADLINE task.
2909 : *
2910 : * Only the static values are considered here, the actual runtime and the
2911 : * absolute deadline will be properly calculated when the task is enqueued
2912 : * for the first time with its new policy.
2913 : */
2914 0 : void __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
2915 : {
2916 0 : struct sched_dl_entity *dl_se = &p->dl;
2917 :
2918 0 : dl_se->dl_runtime = attr->sched_runtime;
2919 0 : dl_se->dl_deadline = attr->sched_deadline;
2920 0 : dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
2921 0 : dl_se->flags = attr->sched_flags & SCHED_DL_FLAGS;
2922 0 : dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
2923 0 : dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime);
2924 0 : }
2925 :
2926 0 : void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
2927 : {
2928 0 : struct sched_dl_entity *dl_se = &p->dl;
2929 :
2930 0 : attr->sched_priority = p->rt_priority;
2931 0 : attr->sched_runtime = dl_se->dl_runtime;
2932 0 : attr->sched_deadline = dl_se->dl_deadline;
2933 0 : attr->sched_period = dl_se->dl_period;
2934 0 : attr->sched_flags &= ~SCHED_DL_FLAGS;
2935 0 : attr->sched_flags |= dl_se->flags;
2936 0 : }
2937 :
2938 : /*
2939 : * This function validates the new parameters of a -deadline task.
2940 : * We ask for the deadline not being zero, and greater or equal
2941 : * than the runtime, as well as the period of being zero or
2942 : * greater than deadline. Furthermore, we have to be sure that
2943 : * user parameters are above the internal resolution of 1us (we
2944 : * check sched_runtime only since it is always the smaller one) and
2945 : * below 2^63 ns (we have to check both sched_deadline and
2946 : * sched_period, as the latter can be zero).
2947 : */
2948 0 : bool __checkparam_dl(const struct sched_attr *attr)
2949 : {
2950 : u64 period, max, min;
2951 :
2952 : /* special dl tasks don't actually use any parameter */
2953 0 : if (attr->sched_flags & SCHED_FLAG_SUGOV)
2954 : return true;
2955 :
2956 : /* deadline != 0 */
2957 0 : if (attr->sched_deadline == 0)
2958 : return false;
2959 :
2960 : /*
2961 : * Since we truncate DL_SCALE bits, make sure we're at least
2962 : * that big.
2963 : */
2964 0 : if (attr->sched_runtime < (1ULL << DL_SCALE))
2965 : return false;
2966 :
2967 : /*
2968 : * Since we use the MSB for wrap-around and sign issues, make
2969 : * sure it's not set (mind that period can be equal to zero).
2970 : */
2971 0 : if (attr->sched_deadline & (1ULL << 63) ||
2972 0 : attr->sched_period & (1ULL << 63))
2973 : return false;
2974 :
2975 0 : period = attr->sched_period;
2976 0 : if (!period)
2977 0 : period = attr->sched_deadline;
2978 :
2979 : /* runtime <= deadline <= period (if period != 0) */
2980 0 : if (period < attr->sched_deadline ||
2981 : attr->sched_deadline < attr->sched_runtime)
2982 : return false;
2983 :
2984 0 : max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC;
2985 0 : min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC;
2986 :
2987 0 : if (period < min || period > max)
2988 : return false;
2989 :
2990 0 : return true;
2991 : }
2992 :
2993 : /*
2994 : * This function clears the sched_dl_entity static params.
2995 : */
2996 176 : void __dl_clear_params(struct task_struct *p)
2997 : {
2998 176 : struct sched_dl_entity *dl_se = &p->dl;
2999 :
3000 176 : dl_se->dl_runtime = 0;
3001 176 : dl_se->dl_deadline = 0;
3002 176 : dl_se->dl_period = 0;
3003 176 : dl_se->flags = 0;
3004 176 : dl_se->dl_bw = 0;
3005 176 : dl_se->dl_density = 0;
3006 :
3007 176 : dl_se->dl_throttled = 0;
3008 176 : dl_se->dl_yielded = 0;
3009 176 : dl_se->dl_non_contending = 0;
3010 176 : dl_se->dl_overrun = 0;
3011 :
3012 : #ifdef CONFIG_RT_MUTEXES
3013 176 : dl_se->pi_se = dl_se;
3014 : #endif
3015 176 : }
3016 :
3017 0 : bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
3018 : {
3019 0 : struct sched_dl_entity *dl_se = &p->dl;
3020 :
3021 0 : if (dl_se->dl_runtime != attr->sched_runtime ||
3022 0 : dl_se->dl_deadline != attr->sched_deadline ||
3023 0 : dl_se->dl_period != attr->sched_period ||
3024 0 : dl_se->flags != (attr->sched_flags & SCHED_DL_FLAGS))
3025 : return true;
3026 :
3027 0 : return false;
3028 : }
3029 :
3030 : #ifdef CONFIG_SMP
3031 : int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
3032 : const struct cpumask *trial)
3033 : {
3034 : unsigned long flags, cap;
3035 : struct dl_bw *cur_dl_b;
3036 : int ret = 1;
3037 :
3038 : rcu_read_lock_sched();
3039 : cur_dl_b = dl_bw_of(cpumask_any(cur));
3040 : cap = __dl_bw_capacity(trial);
3041 : raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
3042 : if (__dl_overflow(cur_dl_b, cap, 0, 0))
3043 : ret = 0;
3044 : raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
3045 : rcu_read_unlock_sched();
3046 :
3047 : return ret;
3048 : }
3049 :
3050 : enum dl_bw_request {
3051 : dl_bw_req_check_overflow = 0,
3052 : dl_bw_req_alloc,
3053 : dl_bw_req_free
3054 : };
3055 :
3056 : static int dl_bw_manage(enum dl_bw_request req, int cpu, u64 dl_bw)
3057 : {
3058 : unsigned long flags;
3059 : struct dl_bw *dl_b;
3060 : bool overflow = 0;
3061 :
3062 : rcu_read_lock_sched();
3063 : dl_b = dl_bw_of(cpu);
3064 : raw_spin_lock_irqsave(&dl_b->lock, flags);
3065 :
3066 : if (req == dl_bw_req_free) {
3067 : __dl_sub(dl_b, dl_bw, dl_bw_cpus(cpu));
3068 : } else {
3069 : unsigned long cap = dl_bw_capacity(cpu);
3070 :
3071 : overflow = __dl_overflow(dl_b, cap, 0, dl_bw);
3072 :
3073 : if (req == dl_bw_req_alloc && !overflow) {
3074 : /*
3075 : * We reserve space in the destination
3076 : * root_domain, as we can't fail after this point.
3077 : * We will free resources in the source root_domain
3078 : * later on (see set_cpus_allowed_dl()).
3079 : */
3080 : __dl_add(dl_b, dl_bw, dl_bw_cpus(cpu));
3081 : }
3082 : }
3083 :
3084 : raw_spin_unlock_irqrestore(&dl_b->lock, flags);
3085 : rcu_read_unlock_sched();
3086 :
3087 : return overflow ? -EBUSY : 0;
3088 : }
3089 :
3090 : int dl_bw_check_overflow(int cpu)
3091 : {
3092 : return dl_bw_manage(dl_bw_req_check_overflow, cpu, 0);
3093 : }
3094 :
3095 : int dl_bw_alloc(int cpu, u64 dl_bw)
3096 : {
3097 : return dl_bw_manage(dl_bw_req_alloc, cpu, dl_bw);
3098 : }
3099 :
3100 : void dl_bw_free(int cpu, u64 dl_bw)
3101 : {
3102 : dl_bw_manage(dl_bw_req_free, cpu, dl_bw);
3103 : }
3104 : #endif
3105 :
3106 : #ifdef CONFIG_SCHED_DEBUG
3107 : void print_dl_stats(struct seq_file *m, int cpu)
3108 : {
3109 : print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
3110 : }
3111 : #endif /* CONFIG_SCHED_DEBUG */
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