Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Block stat tracking code
4 : *
5 : * Copyright (C) 2016 Jens Axboe
6 : */
7 : #include <linux/kernel.h>
8 : #include <linux/rculist.h>
9 : #include <linux/blk-mq.h>
10 :
11 : #include "blk-stat.h"
12 : #include "blk-mq.h"
13 : #include "blk.h"
14 :
15 : struct blk_queue_stats {
16 : struct list_head callbacks;
17 : spinlock_t lock;
18 : int accounting;
19 : };
20 :
21 0 : void blk_rq_stat_init(struct blk_rq_stat *stat)
22 : {
23 0 : stat->min = -1ULL;
24 0 : stat->max = stat->nr_samples = stat->mean = 0;
25 0 : stat->batch = 0;
26 0 : }
27 :
28 : /* src is a per-cpu stat, mean isn't initialized */
29 0 : void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
30 : {
31 0 : if (!src->nr_samples)
32 : return;
33 :
34 0 : dst->min = min(dst->min, src->min);
35 0 : dst->max = max(dst->max, src->max);
36 :
37 0 : dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples,
38 0 : dst->nr_samples + src->nr_samples);
39 :
40 0 : dst->nr_samples += src->nr_samples;
41 : }
42 :
43 0 : void blk_rq_stat_add(struct blk_rq_stat *stat, u64 value)
44 : {
45 0 : stat->min = min(stat->min, value);
46 0 : stat->max = max(stat->max, value);
47 0 : stat->batch += value;
48 0 : stat->nr_samples++;
49 0 : }
50 :
51 0 : void blk_stat_add(struct request *rq, u64 now)
52 : {
53 0 : struct request_queue *q = rq->q;
54 : struct blk_stat_callback *cb;
55 : struct blk_rq_stat *stat;
56 : int bucket, cpu;
57 : u64 value;
58 :
59 0 : value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0;
60 :
61 0 : if (req_op(rq) == REQ_OP_READ || req_op(rq) == REQ_OP_WRITE)
62 : blk_throtl_stat_add(rq, value);
63 :
64 : rcu_read_lock();
65 0 : cpu = get_cpu();
66 0 : list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
67 0 : if (!blk_stat_is_active(cb))
68 0 : continue;
69 :
70 0 : bucket = cb->bucket_fn(rq);
71 0 : if (bucket < 0)
72 0 : continue;
73 :
74 0 : stat = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket];
75 : blk_rq_stat_add(stat, value);
76 : }
77 0 : put_cpu();
78 : rcu_read_unlock();
79 0 : }
80 :
81 0 : static void blk_stat_timer_fn(struct timer_list *t)
82 : {
83 0 : struct blk_stat_callback *cb = from_timer(cb, t, timer);
84 : unsigned int bucket;
85 : int cpu;
86 :
87 0 : for (bucket = 0; bucket < cb->buckets; bucket++)
88 0 : blk_rq_stat_init(&cb->stat[bucket]);
89 :
90 0 : for_each_online_cpu(cpu) {
91 : struct blk_rq_stat *cpu_stat;
92 :
93 0 : cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu);
94 0 : for (bucket = 0; bucket < cb->buckets; bucket++) {
95 0 : blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]);
96 0 : blk_rq_stat_init(&cpu_stat[bucket]);
97 : }
98 : }
99 :
100 0 : cb->timer_fn(cb);
101 0 : }
102 :
103 : struct blk_stat_callback *
104 0 : blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
105 : int (*bucket_fn)(const struct request *),
106 : unsigned int buckets, void *data)
107 : {
108 : struct blk_stat_callback *cb;
109 :
110 0 : cb = kmalloc(sizeof(*cb), GFP_KERNEL);
111 0 : if (!cb)
112 : return NULL;
113 :
114 0 : cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat),
115 : GFP_KERNEL);
116 0 : if (!cb->stat) {
117 0 : kfree(cb);
118 0 : return NULL;
119 : }
120 0 : cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat),
121 : __alignof__(struct blk_rq_stat));
122 0 : if (!cb->cpu_stat) {
123 0 : kfree(cb->stat);
124 0 : kfree(cb);
125 0 : return NULL;
126 : }
127 :
128 0 : cb->timer_fn = timer_fn;
129 0 : cb->bucket_fn = bucket_fn;
130 0 : cb->data = data;
131 0 : cb->buckets = buckets;
132 0 : timer_setup(&cb->timer, blk_stat_timer_fn, 0);
133 :
134 0 : return cb;
135 : }
136 :
137 0 : void blk_stat_add_callback(struct request_queue *q,
138 : struct blk_stat_callback *cb)
139 : {
140 : unsigned int bucket;
141 : unsigned long flags;
142 : int cpu;
143 :
144 0 : for_each_possible_cpu(cpu) {
145 : struct blk_rq_stat *cpu_stat;
146 :
147 0 : cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu);
148 0 : for (bucket = 0; bucket < cb->buckets; bucket++)
149 0 : blk_rq_stat_init(&cpu_stat[bucket]);
150 : }
151 :
152 0 : spin_lock_irqsave(&q->stats->lock, flags);
153 0 : list_add_tail_rcu(&cb->list, &q->stats->callbacks);
154 0 : blk_queue_flag_set(QUEUE_FLAG_STATS, q);
155 0 : spin_unlock_irqrestore(&q->stats->lock, flags);
156 0 : }
157 :
158 0 : void blk_stat_remove_callback(struct request_queue *q,
159 : struct blk_stat_callback *cb)
160 : {
161 : unsigned long flags;
162 :
163 0 : spin_lock_irqsave(&q->stats->lock, flags);
164 0 : list_del_rcu(&cb->list);
165 0 : if (list_empty(&q->stats->callbacks) && !q->stats->accounting)
166 0 : blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
167 0 : spin_unlock_irqrestore(&q->stats->lock, flags);
168 :
169 0 : del_timer_sync(&cb->timer);
170 0 : }
171 :
172 0 : static void blk_stat_free_callback_rcu(struct rcu_head *head)
173 : {
174 : struct blk_stat_callback *cb;
175 :
176 0 : cb = container_of(head, struct blk_stat_callback, rcu);
177 0 : free_percpu(cb->cpu_stat);
178 0 : kfree(cb->stat);
179 0 : kfree(cb);
180 0 : }
181 :
182 0 : void blk_stat_free_callback(struct blk_stat_callback *cb)
183 : {
184 0 : if (cb)
185 0 : call_rcu(&cb->rcu, blk_stat_free_callback_rcu);
186 0 : }
187 :
188 0 : void blk_stat_disable_accounting(struct request_queue *q)
189 : {
190 : unsigned long flags;
191 :
192 0 : spin_lock_irqsave(&q->stats->lock, flags);
193 0 : if (!--q->stats->accounting)
194 0 : blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
195 0 : spin_unlock_irqrestore(&q->stats->lock, flags);
196 0 : }
197 : EXPORT_SYMBOL_GPL(blk_stat_disable_accounting);
198 :
199 0 : void blk_stat_enable_accounting(struct request_queue *q)
200 : {
201 : unsigned long flags;
202 :
203 0 : spin_lock_irqsave(&q->stats->lock, flags);
204 0 : if (!q->stats->accounting++)
205 0 : blk_queue_flag_set(QUEUE_FLAG_STATS, q);
206 0 : spin_unlock_irqrestore(&q->stats->lock, flags);
207 0 : }
208 : EXPORT_SYMBOL_GPL(blk_stat_enable_accounting);
209 :
210 0 : struct blk_queue_stats *blk_alloc_queue_stats(void)
211 : {
212 : struct blk_queue_stats *stats;
213 :
214 0 : stats = kmalloc(sizeof(*stats), GFP_KERNEL);
215 0 : if (!stats)
216 : return NULL;
217 :
218 0 : INIT_LIST_HEAD(&stats->callbacks);
219 0 : spin_lock_init(&stats->lock);
220 0 : stats->accounting = 0;
221 :
222 0 : return stats;
223 : }
224 :
225 0 : void blk_free_queue_stats(struct blk_queue_stats *stats)
226 : {
227 0 : if (!stats)
228 : return;
229 :
230 0 : WARN_ON(!list_empty(&stats->callbacks));
231 :
232 0 : kfree(stats);
233 : }
234 :
235 0 : bool blk_stats_alloc_enable(struct request_queue *q)
236 : {
237 : struct blk_rq_stat *poll_stat;
238 :
239 0 : poll_stat = kcalloc(BLK_MQ_POLL_STATS_BKTS, sizeof(*poll_stat),
240 : GFP_ATOMIC);
241 0 : if (!poll_stat)
242 : return false;
243 :
244 0 : if (cmpxchg(&q->poll_stat, NULL, poll_stat) != NULL) {
245 0 : kfree(poll_stat);
246 0 : return true;
247 : }
248 :
249 0 : blk_stat_add_callback(q, q->poll_cb);
250 0 : return false;
251 : }
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