blk-stat.c 4.8 KB

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  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. #include "blk-stat.h"
  11. #include "blk-mq.h"
  12. #include "blk.h"
  13. struct blk_queue_stats {
  14. struct list_head callbacks;
  15. spinlock_t lock;
  16. bool enable_accounting;
  17. };
  18. void blk_rq_stat_init(struct blk_rq_stat *stat)
  19. {
  20. stat->min = -1ULL;
  21. stat->max = stat->nr_samples = stat->mean = 0;
  22. stat->batch = 0;
  23. }
  24. /* src is a per-cpu stat, mean isn't initialized */
  25. void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
  26. {
  27. if (!src->nr_samples)
  28. return;
  29. dst->min = min(dst->min, src->min);
  30. dst->max = max(dst->max, src->max);
  31. dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples,
  32. dst->nr_samples + src->nr_samples);
  33. dst->nr_samples += src->nr_samples;
  34. }
  35. void blk_rq_stat_add(struct blk_rq_stat *stat, u64 value)
  36. {
  37. stat->min = min(stat->min, value);
  38. stat->max = max(stat->max, value);
  39. stat->batch += value;
  40. stat->nr_samples++;
  41. }
  42. void blk_stat_add(struct request *rq, u64 now)
  43. {
  44. struct request_queue *q = rq->q;
  45. struct blk_stat_callback *cb;
  46. struct blk_rq_stat *stat;
  47. int bucket, cpu;
  48. u64 value;
  49. value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0;
  50. blk_throtl_stat_add(rq, value);
  51. rcu_read_lock();
  52. cpu = get_cpu();
  53. list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
  54. if (!blk_stat_is_active(cb))
  55. continue;
  56. bucket = cb->bucket_fn(rq);
  57. if (bucket < 0)
  58. continue;
  59. stat = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket];
  60. blk_rq_stat_add(stat, value);
  61. }
  62. put_cpu();
  63. rcu_read_unlock();
  64. }
  65. static void blk_stat_timer_fn(struct timer_list *t)
  66. {
  67. struct blk_stat_callback *cb = from_timer(cb, t, timer);
  68. unsigned int bucket;
  69. int cpu;
  70. for (bucket = 0; bucket < cb->buckets; bucket++)
  71. blk_rq_stat_init(&cb->stat[bucket]);
  72. for_each_online_cpu(cpu) {
  73. struct blk_rq_stat *cpu_stat;
  74. cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu);
  75. for (bucket = 0; bucket < cb->buckets; bucket++) {
  76. blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]);
  77. blk_rq_stat_init(&cpu_stat[bucket]);
  78. }
  79. }
  80. cb->timer_fn(cb);
  81. }
  82. struct blk_stat_callback *
  83. blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
  84. int (*bucket_fn)(const struct request *),
  85. unsigned int buckets, void *data)
  86. {
  87. struct blk_stat_callback *cb;
  88. cb = kmalloc(sizeof(*cb), GFP_KERNEL);
  89. if (!cb)
  90. return NULL;
  91. cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat),
  92. GFP_KERNEL);
  93. if (!cb->stat) {
  94. kfree(cb);
  95. return NULL;
  96. }
  97. cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat),
  98. __alignof__(struct blk_rq_stat));
  99. if (!cb->cpu_stat) {
  100. kfree(cb->stat);
  101. kfree(cb);
  102. return NULL;
  103. }
  104. cb->timer_fn = timer_fn;
  105. cb->bucket_fn = bucket_fn;
  106. cb->data = data;
  107. cb->buckets = buckets;
  108. timer_setup(&cb->timer, blk_stat_timer_fn, 0);
  109. return cb;
  110. }
  111. void blk_stat_add_callback(struct request_queue *q,
  112. struct blk_stat_callback *cb)
  113. {
  114. unsigned int bucket;
  115. unsigned long flags;
  116. int cpu;
  117. for_each_possible_cpu(cpu) {
  118. struct blk_rq_stat *cpu_stat;
  119. cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu);
  120. for (bucket = 0; bucket < cb->buckets; bucket++)
  121. blk_rq_stat_init(&cpu_stat[bucket]);
  122. }
  123. spin_lock_irqsave(&q->stats->lock, flags);
  124. list_add_tail_rcu(&cb->list, &q->stats->callbacks);
  125. blk_queue_flag_set(QUEUE_FLAG_STATS, q);
  126. spin_unlock_irqrestore(&q->stats->lock, flags);
  127. }
  128. void blk_stat_remove_callback(struct request_queue *q,
  129. struct blk_stat_callback *cb)
  130. {
  131. unsigned long flags;
  132. spin_lock_irqsave(&q->stats->lock, flags);
  133. list_del_rcu(&cb->list);
  134. if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting)
  135. blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
  136. spin_unlock_irqrestore(&q->stats->lock, flags);
  137. del_timer_sync(&cb->timer);
  138. }
  139. static void blk_stat_free_callback_rcu(struct rcu_head *head)
  140. {
  141. struct blk_stat_callback *cb;
  142. cb = container_of(head, struct blk_stat_callback, rcu);
  143. free_percpu(cb->cpu_stat);
  144. kfree(cb->stat);
  145. kfree(cb);
  146. }
  147. void blk_stat_free_callback(struct blk_stat_callback *cb)
  148. {
  149. if (cb)
  150. call_rcu(&cb->rcu, blk_stat_free_callback_rcu);
  151. }
  152. void blk_stat_enable_accounting(struct request_queue *q)
  153. {
  154. unsigned long flags;
  155. spin_lock_irqsave(&q->stats->lock, flags);
  156. q->stats->enable_accounting = true;
  157. blk_queue_flag_set(QUEUE_FLAG_STATS, q);
  158. spin_unlock_irqrestore(&q->stats->lock, flags);
  159. }
  160. EXPORT_SYMBOL_GPL(blk_stat_enable_accounting);
  161. struct blk_queue_stats *blk_alloc_queue_stats(void)
  162. {
  163. struct blk_queue_stats *stats;
  164. stats = kmalloc(sizeof(*stats), GFP_KERNEL);
  165. if (!stats)
  166. return NULL;
  167. INIT_LIST_HEAD(&stats->callbacks);
  168. spin_lock_init(&stats->lock);
  169. stats->enable_accounting = false;
  170. return stats;
  171. }
  172. void blk_free_queue_stats(struct blk_queue_stats *stats)
  173. {
  174. if (!stats)
  175. return;
  176. WARN_ON(!list_empty(&stats->callbacks));
  177. kfree(stats);
  178. }