diff options
Diffstat (limited to '')
| -rw-r--r-- | block/blk-stat.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/block/blk-stat.c b/block/blk-stat.c new file mode 100644 index 000000000..7587b1c3c --- /dev/null +++ b/block/blk-stat.c @@ -0,0 +1,217 @@ +/* + * Block stat tracking code + * + * Copyright (C) 2016 Jens Axboe + */ +#include <linux/kernel.h> +#include <linux/rculist.h> +#include <linux/blk-mq.h> + +#include "blk-stat.h" +#include "blk-mq.h" +#include "blk.h" + +struct blk_queue_stats { + struct list_head callbacks; + spinlock_t lock; + bool enable_accounting; +}; + +void blk_rq_stat_init(struct blk_rq_stat *stat) +{ + stat->min = -1ULL; + stat->max = stat->nr_samples = stat->mean = 0; + stat->batch = 0; +} + +/* src is a per-cpu stat, mean isn't initialized */ +void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) +{ + if (!src->nr_samples) + return; + + dst->min = min(dst->min, src->min); + dst->max = max(dst->max, src->max); + + dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples, + dst->nr_samples + src->nr_samples); + + dst->nr_samples += src->nr_samples; +} + +void blk_rq_stat_add(struct blk_rq_stat *stat, u64 value) +{ + stat->min = min(stat->min, value); + stat->max = max(stat->max, value); + stat->batch += value; + stat->nr_samples++; +} + +void blk_stat_add(struct request *rq, u64 now) +{ + struct request_queue *q = rq->q; + struct blk_stat_callback *cb; + struct blk_rq_stat *stat; + int bucket; + u64 value; + + value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0; + + blk_throtl_stat_add(rq, value); + + rcu_read_lock(); + list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { + if (!blk_stat_is_active(cb)) + continue; + + bucket = cb->bucket_fn(rq); + if (bucket < 0) + continue; + + stat = &get_cpu_ptr(cb->cpu_stat)[bucket]; + blk_rq_stat_add(stat, value); + put_cpu_ptr(cb->cpu_stat); + } + rcu_read_unlock(); +} + +static void blk_stat_timer_fn(struct timer_list *t) +{ + struct blk_stat_callback *cb = from_timer(cb, t, timer); + unsigned int bucket; + int cpu; + + for (bucket = 0; bucket < cb->buckets; bucket++) + blk_rq_stat_init(&cb->stat[bucket]); + + for_each_online_cpu(cpu) { + struct blk_rq_stat *cpu_stat; + + cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); + for (bucket = 0; bucket < cb->buckets; bucket++) { + blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); + blk_rq_stat_init(&cpu_stat[bucket]); + } + } + + cb->timer_fn(cb); +} + +struct blk_stat_callback * +blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), + int (*bucket_fn)(const struct request *), + unsigned int buckets, void *data) +{ + struct blk_stat_callback *cb; + + cb = kmalloc(sizeof(*cb), GFP_KERNEL); + if (!cb) + return NULL; + + cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat), + GFP_KERNEL); + if (!cb->stat) { + kfree(cb); + return NULL; + } + cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat), + __alignof__(struct blk_rq_stat)); + if (!cb->cpu_stat) { + kfree(cb->stat); + kfree(cb); + return NULL; + } + + cb->timer_fn = timer_fn; + cb->bucket_fn = bucket_fn; + cb->data = data; + cb->buckets = buckets; + timer_setup(&cb->timer, blk_stat_timer_fn, 0); + + return cb; +} +EXPORT_SYMBOL_GPL(blk_stat_alloc_callback); + +void blk_stat_add_callback(struct request_queue *q, + struct blk_stat_callback *cb) +{ + unsigned int bucket; + int cpu; + + for_each_possible_cpu(cpu) { + struct blk_rq_stat *cpu_stat; + + cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); + for (bucket = 0; bucket < cb->buckets; bucket++) + blk_rq_stat_init(&cpu_stat[bucket]); + } + + spin_lock(&q->stats->lock); + list_add_tail_rcu(&cb->list, &q->stats->callbacks); + blk_queue_flag_set(QUEUE_FLAG_STATS, q); + spin_unlock(&q->stats->lock); +} +EXPORT_SYMBOL_GPL(blk_stat_add_callback); + +void blk_stat_remove_callback(struct request_queue *q, + struct blk_stat_callback *cb) +{ + spin_lock(&q->stats->lock); + list_del_rcu(&cb->list); + if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting) + blk_queue_flag_clear(QUEUE_FLAG_STATS, q); + spin_unlock(&q->stats->lock); + + del_timer_sync(&cb->timer); +} +EXPORT_SYMBOL_GPL(blk_stat_remove_callback); + +static void blk_stat_free_callback_rcu(struct rcu_head *head) +{ + struct blk_stat_callback *cb; + + cb = container_of(head, struct blk_stat_callback, rcu); + free_percpu(cb->cpu_stat); + kfree(cb->stat); + kfree(cb); +} + +void blk_stat_free_callback(struct blk_stat_callback *cb) +{ + if (cb) + call_rcu(&cb->rcu, blk_stat_free_callback_rcu); +} +EXPORT_SYMBOL_GPL(blk_stat_free_callback); + +void blk_stat_enable_accounting(struct request_queue *q) +{ + spin_lock(&q->stats->lock); + q->stats->enable_accounting = true; + blk_queue_flag_set(QUEUE_FLAG_STATS, q); + spin_unlock(&q->stats->lock); +} + +struct blk_queue_stats *blk_alloc_queue_stats(void) +{ + struct blk_queue_stats *stats; + + stats = kmalloc(sizeof(*stats), GFP_KERNEL); + if (!stats) + return NULL; + + INIT_LIST_HEAD(&stats->callbacks); + spin_lock_init(&stats->lock); + stats->enable_accounting = false; + + return stats; +} + +void blk_free_queue_stats(struct blk_queue_stats *stats) +{ + if (!stats) + return; + + WARN_ON(!list_empty(&stats->callbacks)); + + kfree(stats); +} |