diff options
| -rw-r--r-- | block/blk-core.c | 6 | ||||
| -rw-r--r-- | block/blk-mq-debugfs.c | 99 | ||||
| -rw-r--r-- | block/blk-mq.c | 76 | ||||
| -rw-r--r-- | block/blk-mq.h | 1 | ||||
| -rw-r--r-- | block/blk-stat.c | 311 | ||||
| -rw-r--r-- | block/blk-stat.h | 181 | ||||
| -rw-r--r-- | block/blk-sysfs.c | 31 | ||||
| -rw-r--r-- | block/blk-wbt.c | 51 | ||||
| -rw-r--r-- | block/blk-wbt.h | 2 | ||||
| -rw-r--r-- | include/linux/blk_types.h | 1 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 10 |
11 files changed, 449 insertions, 320 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index e8a9bc0d4bbb..78d04ddededc 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -852,6 +852,10 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio); int blk_init_allocated_queue(struct request_queue *q) { + q->stats = blk_alloc_queue_stats(); + if (!q->stats) + return -ENOMEM; + q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size); if (!q->fq) return -ENOMEM; @@ -2698,7 +2702,7 @@ void blk_finish_request(struct request *req, int error) struct request_queue *q = req->q; if (req->rq_flags & RQF_STATS) - blk_stat_add(&q->rq_stats[rq_data_dir(req)], req); + blk_stat_add(req); if (req->rq_flags & RQF_QUEUED) blk_queue_end_tag(q, req); diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 48c88723944a..4b3f962a9c7a 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -43,6 +43,42 @@ static int blk_mq_debugfs_seq_open(struct inode *inode, struct file *file, return ret; } +static void print_stat(struct seq_file *m, struct blk_rq_stat *stat) +{ + if (stat->nr_samples) { + seq_printf(m, "samples=%d, mean=%lld, min=%llu, max=%llu", + stat->nr_samples, stat->mean, stat->min, stat->max); + } else { + seq_puts(m, "samples=0"); + } +} + +static int queue_poll_stat_show(struct seq_file *m, void *v) +{ + struct request_queue *q = m->private; + + seq_puts(m, "read: "); + print_stat(m, &q->poll_stat[READ]); + seq_puts(m, "\n"); + + seq_puts(m, "write: "); + print_stat(m, &q->poll_stat[WRITE]); + seq_puts(m, "\n"); + return 0; +} + +static int queue_poll_stat_open(struct inode *inode, struct file *file) +{ + return single_open(file, queue_poll_stat_show, inode->i_private); +} + +static const struct file_operations queue_poll_stat_fops = { + .open = queue_poll_stat_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + static int hctx_state_show(struct seq_file *m, void *v) { struct blk_mq_hw_ctx *hctx = m->private; @@ -322,60 +358,6 @@ static const struct file_operations hctx_io_poll_fops = { .release = single_release, }; -static void print_stat(struct seq_file *m, struct blk_rq_stat *stat) -{ - seq_printf(m, "samples=%d, mean=%lld, min=%llu, max=%llu", - stat->nr_samples, stat->mean, stat->min, stat->max); -} - -static int hctx_stats_show(struct seq_file *m, void *v) -{ - struct blk_mq_hw_ctx *hctx = m->private; - struct blk_rq_stat stat[2]; - - blk_stat_init(&stat[READ]); - blk_stat_init(&stat[WRITE]); - - blk_hctx_stat_get(hctx, stat); - - seq_puts(m, "read: "); - print_stat(m, &stat[READ]); - seq_puts(m, "\n"); - - seq_puts(m, "write: "); - print_stat(m, &stat[WRITE]); - seq_puts(m, "\n"); - return 0; -} - -static int hctx_stats_open(struct inode *inode, struct file *file) -{ - return single_open(file, hctx_stats_show, inode->i_private); -} - -static ssize_t hctx_stats_write(struct file *file, const char __user *buf, - size_t count, loff_t *ppos) -{ - struct seq_file *m = file->private_data; - struct blk_mq_hw_ctx *hctx = m->private; - struct blk_mq_ctx *ctx; - int i; - - hctx_for_each_ctx(hctx, ctx, i) { - blk_stat_init(&ctx->stat[READ]); - blk_stat_init(&ctx->stat[WRITE]); - } - return count; -} - -static const struct file_operations hctx_stats_fops = { - .open = hctx_stats_open, - .read = seq_read, - .write = hctx_stats_write, - .llseek = seq_lseek, - .release = single_release, -}; - static int hctx_dispatched_show(struct seq_file *m, void *v) { struct blk_mq_hw_ctx *hctx = m->private; @@ -636,6 +618,11 @@ static const struct file_operations ctx_completed_fops = { .release = single_release, }; +static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = { + {"poll_stat", 0400, &queue_poll_stat_fops}, + {}, +}; + static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = { {"state", 0400, &hctx_state_fops}, {"flags", 0400, &hctx_flags_fops}, @@ -646,7 +633,6 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = { {"sched_tags", 0400, &hctx_sched_tags_fops}, {"sched_tags_bitmap", 0400, &hctx_sched_tags_bitmap_fops}, {"io_poll", 0600, &hctx_io_poll_fops}, - {"stats", 0600, &hctx_stats_fops}, {"dispatched", 0600, &hctx_dispatched_fops}, {"queued", 0600, &hctx_queued_fops}, {"run", 0600, &hctx_run_fops}, @@ -753,6 +739,9 @@ int blk_mq_debugfs_register_hctxs(struct request_queue *q) if (!q->mq_debugfs_dir) goto err; + if (!debugfs_create_files(q->mq_debugfs_dir, q, blk_mq_debugfs_queue_attrs)) + goto err; + queue_for_each_hw_ctx(q, hctx, i) { if (blk_mq_debugfs_register_hctx(q, hctx)) goto err; diff --git a/block/blk-mq.c b/block/blk-mq.c index 559e5363bb2c..5ff66f203cd0 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -39,6 +39,9 @@ static DEFINE_MUTEX(all_q_mutex); static LIST_HEAD(all_q_list); +static void blk_mq_poll_stats_start(struct request_queue *q); +static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb); + /* * Check if any of the ctx's have pending work in this hardware queue */ @@ -432,15 +435,8 @@ static void blk_mq_ipi_complete_request(struct request *rq) static void blk_mq_stat_add(struct request *rq) { if (rq->rq_flags & RQF_STATS) { - /* - * We could rq->mq_ctx here, but there's less of a risk - * of races if we have the completion event add the stats - * to the local software queue. - */ - struct blk_mq_ctx *ctx; - - ctx = __blk_mq_get_ctx(rq->q, raw_smp_processor_id()); - blk_stat_add(&ctx->stat[rq_data_dir(rq)], rq); + blk_mq_poll_stats_start(rq->q); + blk_stat_add(rq); } } @@ -2040,8 +2036,6 @@ static void blk_mq_init_cpu_queues(struct request_queue *q, spin_lock_init(&__ctx->lock); INIT_LIST_HEAD(&__ctx->rq_list); __ctx->queue = q; - blk_stat_init(&__ctx->stat[READ]); - blk_stat_init(&__ctx->stat[WRITE]); /* If the cpu isn't online, the cpu is mapped to first hctx */ if (!cpu_online(i)) @@ -2339,6 +2333,15 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, /* mark the queue as mq asap */ q->mq_ops = set->ops; + q->stats = blk_alloc_queue_stats(); + if (!q->stats) + goto err_exit; + + q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn, + blk_stat_rq_ddir, 2, q); + if (!q->poll_cb) + goto err_exit; + q->queue_ctx = alloc_percpu(struct blk_mq_ctx); if (!q->queue_ctx) goto err_exit; @@ -2740,28 +2743,53 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) } EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues); +/* Enable polling stats and return whether they were already enabled. */ +static bool blk_poll_stats_enable(struct request_queue *q) +{ + if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) || + test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags)) + return true; + blk_stat_add_callback(q, q->poll_cb); + return false; +} + +static void blk_mq_poll_stats_start(struct request_queue *q) +{ + /* + * We don't arm the callback if polling stats are not enabled or the + * callback is already active. + */ + if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) || + blk_stat_is_active(q->poll_cb)) + return; + + blk_stat_activate_msecs(q->poll_cb, 100); +} + +static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb) +{ + struct request_queue *q = cb->data; + + if (cb->stat[READ].nr_samples) + q->poll_stat[READ] = cb->stat[READ]; + if (cb->stat[WRITE].nr_samples) + q->poll_stat[WRITE] = cb->stat[WRITE]; +} + static unsigned long blk_mq_poll_nsecs(struct request_queue *q, struct blk_mq_hw_ctx *hctx, struct request *rq) { - struct blk_rq_stat stat[2]; unsigned long ret = 0; /* * If stats collection isn't on, don't sleep but turn it on for * future users */ - if (!blk_stat_enable(q)) + if (!blk_poll_stats_enable(q)) return 0; /* - * We don't have to do this once per IO, should optimize this - * to just use the current window of stats until it changes - */ - memset(&stat, 0, sizeof(stat)); - blk_hctx_stat_get(hctx, stat); - - /* * As an optimistic guess, use half of the mean service time * for this type of request. We can (and should) make this smarter. * For instance, if the completion latencies are tight, we can @@ -2769,10 +2797,10 @@ static unsigned long blk_mq_poll_nsecs(struct request_queue *q, * important on devices where the completion latencies are longer * than ~10 usec. */ - if (req_op(rq) == REQ_OP_READ && stat[READ].nr_samples) - ret = (stat[READ].mean + 1) / 2; - else if (req_op(rq) == REQ_OP_WRITE && stat[WRITE].nr_samples) - ret = (stat[WRITE].mean + 1) / 2; + if (req_op(rq) == REQ_OP_READ && q->poll_stat[READ].nr_samples) + ret = (q->poll_stat[READ].mean + 1) / 2; + else if (req_op(rq) == REQ_OP_WRITE && q->poll_stat[WRITE].nr_samples) + ret = (q->poll_stat[WRITE].mean + 1) / 2; return ret; } diff --git a/block/blk-mq.h b/block/blk-mq.h index b79f9a7d8cf6..8d49c06fc520 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -20,7 +20,6 @@ struct blk_mq_ctx { /* incremented at completion time */ unsigned long ____cacheline_aligned_in_smp rq_completed[2]; - struct blk_rq_stat stat[2]; struct request_queue *queue; struct kobject kobj; diff --git a/block/blk-stat.c b/block/blk-stat.c index 4681c488c262..0d8721a60db9 100644 --- a/block/blk-stat.c +++ b/block/blk-stat.c @@ -4,6 +4,7 @@ * Copyright (C) 2016 Jens Axboe */ #include <linux/kernel.h> +#include <linux/rculist.h> #include <linux/blk-mq.h> #include "blk-stat.h" @@ -11,6 +12,24 @@ #define BLK_RQ_STAT_BATCH 64 +struct blk_queue_stats { + struct list_head callbacks; + spinlock_t lock; +}; + +unsigned int blk_stat_rq_ddir(const struct request *rq) +{ + return rq_data_dir(rq); +} +EXPORT_SYMBOL_GPL(blk_stat_rq_ddir); + +static void blk_stat_init(struct blk_rq_stat *stat) +{ + stat->min = -1ULL; + stat->max = stat->nr_samples = stat->mean = 0; + stat->batch = stat->nr_batch = 0; +} + static void blk_stat_flush_batch(struct blk_rq_stat *stat) { const s32 nr_batch = READ_ONCE(stat->nr_batch); @@ -50,207 +69,171 @@ static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) dst->nr_samples += src->nr_samples; } -static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst) +static void __blk_stat_add(struct blk_rq_stat *stat, u64 value) { - struct blk_mq_hw_ctx *hctx; - struct blk_mq_ctx *ctx; - uint64_t latest = 0; - int i, j, nr; - - blk_stat_init(&dst[READ]); - blk_stat_init(&dst[WRITE]); - - nr = 0; - do { - uint64_t newest = 0; - - queue_for_each_hw_ctx(q, hctx, i) { - hctx_for_each_ctx(hctx, ctx, j) { - blk_stat_flush_batch(&ctx->stat[READ]); - blk_stat_flush_batch(&ctx->stat[WRITE]); - - if (!ctx->stat[READ].nr_samples && - !ctx->stat[WRITE].nr_samples) - continue; - if (ctx->stat[READ].time > newest) - newest = ctx->stat[READ].time; - if (ctx->stat[WRITE].time > newest) - newest = ctx->stat[WRITE].time; - } - } + stat->min = min(stat->min, value); + stat->max = max(stat->max, value); - /* - * No samples - */ - if (!newest) - break; - - if (newest > latest) - latest = newest; - - queue_for_each_hw_ctx(q, hctx, i) { - hctx_for_each_ctx(hctx, ctx, j) { - if (ctx->stat[READ].time == newest) { - blk_stat_sum(&dst[READ], - &ctx->stat[READ]); - nr++; - } - if (ctx->stat[WRITE].time == newest) { - blk_stat_sum(&dst[WRITE], - &ctx->stat[WRITE]); - nr++; - } - } - } - /* - * If we race on finding an entry, just loop back again. - * Should be very rare. - */ - } while (!nr); + if (stat->batch + value < stat->batch || + stat->nr_batch + 1 == BLK_RQ_STAT_BATCH) + blk_stat_flush_batch(stat); - dst[READ].time = dst[WRITE].time = latest; + stat->batch += value; + stat->nr_batch++; } -void blk_queue_stat_get(struct request_queue *q, struct blk_rq_stat *dst) +void blk_stat_add(struct request *rq) { - if (q->mq_ops) - blk_mq_stat_get(q, dst); - else { - blk_stat_flush_batch(&q->rq_stats[READ]); - blk_stat_flush_batch(&q->rq_stats[WRITE]); - memcpy(&dst[READ], &q->rq_stats[READ], - sizeof(struct blk_rq_stat)); - memcpy(&dst[WRITE], &q->rq_stats[WRITE], - sizeof(struct blk_rq_stat)); + struct request_queue *q = rq->q; + struct blk_stat_callback *cb; + struct blk_rq_stat *stat; + int bucket; + s64 now, value; + + now = __blk_stat_time(ktime_to_ns(ktime_get())); + if (now < blk_stat_time(&rq->issue_stat)) + return; + + value = now - blk_stat_time(&rq->issue_stat); + + rcu_read_lock(); + list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { + if (blk_stat_is_active(cb)) { + bucket = cb->bucket_fn(rq); + stat = &this_cpu_ptr(cb->cpu_stat)[bucket]; + __blk_stat_add(stat, value); + } } + rcu_read_unlock(); } -void blk_hctx_stat_get(struct blk_mq_hw_ctx *hctx, struct blk_rq_stat *dst) +static void blk_stat_timer_fn(unsigned long data) { - struct blk_mq_ctx *ctx; - unsigned int i, nr; + struct blk_stat_callback *cb = (void *)data; + unsigned int bucket; + int cpu; - nr = 0; - do { - uint64_t newest = 0; + for (bucket = 0; bucket < cb->buckets; bucket++) + blk_stat_init(&cb->stat[bucket]); - hctx_for_each_ctx(hctx, ctx, i) { - blk_stat_flush_batch(&ctx->stat[READ]); - blk_stat_flush_batch(&ctx->stat[WRITE]); + for_each_online_cpu(cpu) { + struct blk_rq_stat *cpu_stat; - if (!ctx->stat[READ].nr_samples && - !ctx->stat[WRITE].nr_samples) - continue; - - if (ctx->stat[READ].time > newest) - newest = ctx->stat[READ].time; - if (ctx->stat[WRITE].time > newest) - newest = ctx->stat[WRITE].time; + cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); + for (bucket = 0; bucket < cb->buckets; bucket++) { + blk_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); + blk_stat_init(&cpu_stat[bucket]); } + } - if (!newest) - break; - - hctx_for_each_ctx(hctx, ctx, i) { - if (ctx->stat[READ].time == newest) { - blk_stat_sum(&dst[READ], &ctx->stat[READ]); - nr++; - } - if (ctx->stat[WRITE].time == newest) { - blk_stat_sum(&dst[WRITE], &ctx->stat[WRITE]); - nr++; - } - } - /* - * If we race on finding an entry, just loop back again. - * Should be very rare, as the window is only updated - * occasionally - */ - } while (!nr); + cb->timer_fn(cb); } -static void __blk_stat_init(struct blk_rq_stat *stat, s64 time_now) +struct blk_stat_callback * +blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), + unsigned int (*bucket_fn)(const struct request *), + unsigned int buckets, void *data) { - stat->min = -1ULL; - stat->max = stat->nr_samples = stat->mean = 0; - stat->batch = stat->nr_batch = 0; - stat->time = time_now & BLK_STAT_NSEC_MASK; -} + struct blk_stat_callback *cb; -void blk_stat_init(struct blk_rq_stat *stat) -{ - __blk_stat_init(stat, ktime_to_ns(ktime_get())); -} + cb = kmalloc(sizeof(*cb), GFP_KERNEL); + if (!cb) + return NULL; -static bool __blk_stat_is_current(struct blk_rq_stat *stat, s64 now) -{ - return (now & BLK_STAT_NSEC_MASK) == (stat->time & BLK_STAT_NSEC_MASK); -} + 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; + } -bool blk_stat_is_current(struct blk_rq_stat *stat) -{ - return __blk_stat_is_current(stat, ktime_to_ns(ktime_get())); + cb->timer_fn = timer_fn; + cb->bucket_fn = bucket_fn; + cb->data = data; + cb->buckets = buckets; + setup_timer(&cb->timer, blk_stat_timer_fn, (unsigned long)cb); + + return cb; } +EXPORT_SYMBOL_GPL(blk_stat_alloc_callback); -void blk_stat_add(struct blk_rq_stat *stat, struct request *rq) +void blk_stat_add_callback(struct request_queue *q, + struct blk_stat_callback *cb) { - s64 now, value; + unsigned int bucket; + int cpu; - now = __blk_stat_time(ktime_to_ns(ktime_get())); - if (now < blk_stat_time(&rq->issue_stat)) - return; + for_each_possible_cpu(cpu) { + struct blk_rq_stat *cpu_stat; - if (!__blk_stat_is_current(stat, now)) - __blk_stat_init(stat, now); + cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); + for (bucket = 0; bucket < cb->buckets; bucket++) + blk_stat_init(&cpu_stat[bucket]); + } - value = now - blk_stat_time(&rq->issue_stat); - if (value > stat->max) - stat->max = value; - if (value < stat->min) - stat->min = value; + spin_lock(&q->stats->lock); + list_add_tail_rcu(&cb->list, &q->stats->callbacks); + set_bit(QUEUE_FLAG_STATS, &q->queue_flags); + spin_unlock(&q->stats->lock); +} +EXPORT_SYMBOL_GPL(blk_stat_add_callback); - if (stat->batch + value < stat->batch || - stat->nr_batch + 1 == BLK_RQ_STAT_BATCH) - blk_stat_flush_batch(stat); +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)) + clear_bit(QUEUE_FLAG_STATS, &q->queue_flags); + spin_unlock(&q->stats->lock); - stat->batch += value; - stat->nr_batch++; + del_timer_sync(&cb->timer); } +EXPORT_SYMBOL_GPL(blk_stat_remove_callback); -void blk_stat_clear(struct request_queue *q) +static void blk_stat_free_callback_rcu(struct rcu_head *head) { - if (q->mq_ops) { - struct blk_mq_hw_ctx *hctx; - struct blk_mq_ctx *ctx; - int i, j; - - queue_for_each_hw_ctx(q, hctx, i) { - hctx_for_each_ctx(hctx, ctx, j) { - blk_stat_init(&ctx->stat[READ]); - blk_stat_init(&ctx->stat[WRITE]); - } - } - } else { - blk_stat_init(&q->rq_stats[READ]); - blk_stat_init(&q->rq_stats[WRITE]); - } + 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_set_issue_time(struct blk_issue_stat *stat) +void blk_stat_free_callback(struct blk_stat_callback *cb) { - stat->time = (stat->time & BLK_STAT_MASK) | - (ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK); + call_rcu(&cb->rcu, blk_stat_free_callback_rcu); } +EXPORT_SYMBOL_GPL(blk_stat_free_callback); -/* - * Enable stat tracking, return whether it was enabled - */ -bool blk_stat_enable(struct request_queue *q) +struct blk_queue_stats *blk_alloc_queue_stats(void) { - if (!test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) { - set_bit(QUEUE_FLAG_STATS, &q->queue_flags); - return false; - } + 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); + + return stats; +} + +void blk_free_queue_stats(struct blk_queue_stats *stats) +{ + if (!stats) + return; + + WARN_ON(!list_empty(&stats->callbacks)); - return true; + kfree(stats); } diff --git a/block/blk-stat.h b/block/blk-stat.h index 34384328b46b..6ad5b8c59a79 100644 --- a/block/blk-stat.h +++ b/block/blk-stat.h @@ -1,11 +1,11 @@ #ifndef BLK_STAT_H #define BLK_STAT_H -/* - * ~0.13s window as a power-of-2 (2^27 nsecs) - */ -#define BLK_STAT_NSEC 134217728ULL -#define BLK_STAT_NSEC_MASK ~(BLK_STAT_NSEC - 1) +#include <linux/kernel.h> +#include <linux/blkdev.h> +#include <linux/ktime.h> +#include <linux/rcupdate.h> +#include <linux/timer.h> /* * Upper 3 bits can be used elsewhere @@ -15,14 +15,69 @@ #define BLK_STAT_TIME_MASK ((1ULL << BLK_STAT_SHIFT) - 1) #define BLK_STAT_MASK ~BLK_STAT_TIME_MASK -void blk_stat_add(struct blk_rq_stat *, struct request *); -void blk_hctx_stat_get(struct blk_mq_hw_ctx *, struct blk_rq_stat *); -void blk_queue_stat_get(struct request_queue *, struct blk_rq_stat *); -void blk_stat_clear(struct request_queue *); -void blk_stat_init(struct blk_rq_stat *); -bool blk_stat_is_current(struct blk_rq_stat *); -void blk_stat_set_issue_time(struct blk_issue_stat *); -bool blk_stat_enable(struct request_queue *); +/** + * struct blk_stat_callback - Block statistics callback. + * + * A &struct blk_stat_callback is associated with a &struct request_queue. While + * @timer is active, that queue's request completion latencies are sorted into + * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the + * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked. + */ +struct blk_stat_callback { + /* + * @list: RCU list of callbacks for a &struct request_queue. + */ + struct list_head list; + + /** + * @timer: Timer for the next callback invocation. + */ + struct timer_list timer; + + /** + * @cpu_stat: Per-cpu statistics buckets. + */ + struct blk_rq_stat __percpu *cpu_stat; + + /** + * @bucket_fn: Given a request, returns which statistics bucket it + * should be accounted under. + */ + unsigned int (*bucket_fn)(const struct request *); + + /** + * @buckets: Number of statistics buckets. + */ + unsigned int buckets; + + /** + * @stat: Array of statistics buckets. + */ + struct blk_rq_stat *stat; + + /** + * @fn: Callback function. + */ + void (*timer_fn)(struct blk_stat_callback *); + + /** + * @data: Private pointer for the user. + */ + void *data; + + struct rcu_head rcu; +}; + +struct blk_queue_stats *blk_alloc_queue_stats(void); +void blk_free_queue_stats(struct blk_queue_stats *); + +void blk_stat_add(struct request *); + +static inline void blk_stat_set_issue_time(struct blk_issue_stat *stat) +{ + stat->time = ((stat->time & BLK_STAT_MASK) | + (ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK)); +} static inline u64 __blk_stat_time(u64 time) { @@ -34,4 +89,104 @@ static inline u64 blk_stat_time(struct blk_issue_stat *stat) return __blk_stat_time(stat->time); } +/* + * blk_stat_rq_ddir() - Bucket callback function for the request data direction. + * @rq: Request. + * + * This is the same as rq_data_dir() but as a function so it can be used as + * @bucket_fn for blk_stat_alloc_callback(). + * + * Return: Data direction of the request, either READ or WRITE. + */ +unsigned int blk_stat_rq_ddir(const struct request *rq); + +/** + * blk_stat_alloc_callback() - Allocate a block statistics callback. + * @timer_fn: Timer callback function. + * @bucket_fn: Bucket callback function. + * @buckets: Number of statistics buckets. + * @data: Value for the @data field of the &struct blk_stat_callback. + * + * See &struct blk_stat_callback for details on the callback functions. + * + * Return: &struct blk_stat_callback on success or NULL on ENOMEM. + */ +struct blk_stat_callback * +blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), + unsigned int (*bucket_fn)(const struct request *), + unsigned int buckets, void *data); + +/** + * blk_stat_add_callback() - Add a block statistics callback to be run on a + * request queue. + * @q: The request queue. + * @cb: The callback. + * + * Note that a single &struct blk_stat_callback can only be added to a single + * &struct request_queue. + */ +void blk_stat_add_callback(struct request_queue *q, + struct blk_stat_callback *cb); + +/** + * blk_stat_remove_callback() - Remove a block statistics callback from a + * request queue. + * @q: The request queue. + * @cb: The callback. + * + * When this returns, the callback is not running on any CPUs and will not be + * called again unless readded. + */ +void blk_stat_remove_callback(struct request_queue *q, + struct blk_stat_callback *cb); + +/** + * blk_stat_free_callback() - Free a block statistics callback. + * @cb: The callback. + * + * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must + * not be associated with a request queue. I.e., if it was previously added with + * blk_stat_add_callback(), it must also have been removed since then with + * blk_stat_remove_callback(). + */ +void blk_stat_free_callback(struct blk_stat_callback *cb); + +/** + * blk_stat_is_active() - Check if a block statistics callback is currently + * gathering statistics. + * @cb: The callback. + */ +static inline bool blk_stat_is_active(struct blk_stat_callback *cb) +{ + return timer_pending(&cb->timer); +} + +/** + * blk_stat_activate_nsecs() - Gather block statistics during a time window in + * nanoseconds. + * @cb: The callback. + * @nsecs: Number of nanoseconds to gather statistics for. + * + * The timer callback will be called when the window expires. + */ +static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb, + u64 nsecs) +{ + mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs)); +} + +/** + * blk_stat_activate_msecs() - Gather block statistics during a time window in + * milliseconds. + * @cb: The callback. + * @msecs: Number of milliseconds to gather statistics for. + * + * The timer callback will be called when the window expires. + */ +static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb, + unsigned int msecs) +{ + mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs)); +} + #endif diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index fdb45fd0db0b..fa831cb2fc30 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -503,26 +503,6 @@ static ssize_t queue_dax_show(struct request_queue *q, char *page) return queue_var_show(blk_queue_dax(q), page); } -static ssize_t print_stat(char *page, struct blk_rq_stat *stat, const char *pre) -{ - return sprintf(page, "%s samples=%llu, mean=%lld, min=%lld, max=%lld\n", - pre, (long long) stat->nr_samples, - (long long) stat->mean, (long long) stat->min, - (long long) stat->max); -} - -static ssize_t queue_stats_show(struct request_queue *q, char *page) -{ - struct blk_rq_stat stat[2]; - ssize_t ret; - - blk_queue_stat_get(q, stat); - - ret = print_stat(page, &stat[READ], "read :"); - ret += print_stat(page + ret, &stat[WRITE], "write:"); - return ret; -} - static struct queue_sysfs_entry queue_requests_entry = { .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, .show = queue_requests_show, @@ -691,11 +671,6 @@ static struct queue_sysfs_entry queue_dax_entry = { .show = queue_dax_show, }; -static struct queue_sysfs_entry queue_stats_entry = { - .attr = {.name = "stats", .mode = S_IRUGO }, - .show = queue_stats_show, -}; - static struct queue_sysfs_entry queue_wb_lat_entry = { .attr = {.name = "wbt_lat_usec", .mode = S_IRUGO | S_IWUSR }, .show = queue_wb_lat_show, @@ -733,7 +708,6 @@ static struct attribute *default_attrs[] = { &queue_poll_entry.attr, &queue_wc_entry.attr, &queue_dax_entry.attr, - &queue_stats_entry.attr, &queue_wb_lat_entry.attr, &queue_poll_delay_entry.attr, NULL, @@ -811,6 +785,9 @@ static void blk_release_queue(struct kobject *kobj) container_of(kobj, struct request_queue, kobj); wbt_exit(q); + if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags)) + blk_stat_remove_callback(q, q->poll_cb); + blk_stat_free_callback(q->poll_cb); bdi_put(q->backing_dev_info); blkcg_exit_queue(q); @@ -819,6 +796,8 @@ static void blk_release_queue(struct kobject *kobj) elevator_exit(q->elevator); } + blk_free_queue_stats(q->stats); + blk_exit_rl(&q->root_rl); if (q->queue_tags) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index aafe5b551224..ffa80e11cf14 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -277,7 +277,7 @@ enum { LAT_EXCEEDED, }; -static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) +static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) { struct backing_dev_info *bdi = rwb->queue->backing_dev_info; u64 thislat; @@ -308,8 +308,8 @@ static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) * waited or still has writes in flights, consider us doing * just writes as well. */ - if ((stat[WRITE].nr_samples && blk_stat_is_current(stat)) || - wb_recent_wait(rwb) || wbt_inflight(rwb)) + if (stat[WRITE].nr_samples || wb_recent_wait(rwb) || + wbt_inflight(rwb)) return LAT_UNKNOWN_WRITES; return LAT_UNKNOWN; } @@ -329,14 +329,6 @@ static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) return LAT_OK; } -static int latency_exceeded(struct rq_wb *rwb) -{ - struct blk_rq_stat stat[2]; - - blk_queue_stat_get(rwb->queue, stat); - return __latency_exceeded(rwb, stat); -} - static void rwb_trace_step(struct rq_wb *rwb, const char *msg) { struct backing_dev_info *bdi = rwb->queue->backing_dev_info; @@ -355,7 +347,6 @@ static void scale_up(struct rq_wb *rwb) rwb->scale_step--; rwb->unknown_cnt = 0; - blk_stat_clear(rwb->queue); rwb->scaled_max = calc_wb_limits(rwb); @@ -385,15 +376,12 @@ static void scale_down(struct rq_wb *rwb, bool hard_throttle) rwb->scaled_max = false; rwb->unknown_cnt = 0; - blk_stat_clear(rwb->queue); calc_wb_limits(rwb); rwb_trace_step(rwb, "step down"); } static void rwb_arm_timer(struct rq_wb *rwb) { - unsigned long expires; - if (rwb->scale_step > 0) { /* * We should speed this up, using some variant of a fast @@ -411,17 +399,16 @@ static void rwb_arm_timer(struct rq_wb *rwb) rwb->cur_win_nsec = rwb->win_nsec; } - expires = jiffies + nsecs_to_jiffies(rwb->cur_win_nsec); - mod_timer(&rwb->window_timer, expires); + blk_stat_activate_nsecs(rwb->cb, rwb->cur_win_nsec); } -static void wb_timer_fn(unsigned long data) +static void wb_timer_fn(struct blk_stat_callback *cb) { - struct rq_wb *rwb = (struct rq_wb *) data; + struct rq_wb *rwb = cb->data; unsigned int inflight = wbt_inflight(rwb); int status; - status = latency_exceeded(rwb); + status = latency_exceeded(rwb, cb->stat); trace_wbt_timer(rwb->queue->backing_dev_info, status, rwb->scale_step, inflight); @@ -614,7 +601,7 @@ enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock) __wbt_wait(rwb, bio->bi_opf, lock); - if (!timer_pending(&rwb->window_timer)) + if (!blk_stat_is_active(rwb->cb)) rwb_arm_timer(rwb); if (current_is_kswapd()) @@ -675,7 +662,7 @@ void wbt_disable_default(struct request_queue *q) struct rq_wb *rwb = q->rq_wb; if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT) { - del_timer_sync(&rwb->window_timer); + blk_stat_remove_callback(q, rwb->cb); rwb->win_nsec = rwb->min_lat_nsec = 0; wbt_update_limits(rwb); } @@ -699,24 +686,23 @@ int wbt_init(struct request_queue *q) struct rq_wb *rwb; int i; - /* - * For now, we depend on the stats window being larger than - * our monitoring window. Ensure that this isn't inadvertently - * violated. - */ - BUILD_BUG_ON(RWB_WINDOW_NSEC > BLK_STAT_NSEC); BUILD_BUG_ON(WBT_NR_BITS > BLK_STAT_RES_BITS); rwb = kzalloc(sizeof(*rwb), GFP_KERNEL); if (!rwb) return -ENOMEM; + rwb->cb = blk_stat_alloc_callback(wb_timer_fn, blk_stat_rq_ddir, 2, rwb); + if (!rwb->cb) { + kfree(rwb); + return -ENOMEM; + } + for (i = 0; i < WBT_NUM_RWQ; i++) { atomic_set(&rwb->rq_wait[i].inflight, 0); init_waitqueue_head(&rwb->rq_wait[i].wait); } - setup_timer(&rwb->window_timer, wb_timer_fn, (unsigned long) rwb); rwb->wc = 1; rwb->queue_depth = RWB_DEF_DEPTH; rwb->last_comp = rwb->last_issue = jiffies; @@ -726,10 +712,10 @@ int wbt_init(struct request_queue *q) wbt_update_limits(rwb); /* - * Assign rwb, and turn on stats tracking for this queue + * Assign rwb and add the stats callback. */ q->rq_wb = rwb; - blk_stat_enable(q); + blk_stat_add_callback(q, rwb->cb); rwb->min_lat_nsec = wbt_default_latency_nsec(q); @@ -744,7 +730,8 @@ void wbt_exit(struct request_queue *q) struct rq_wb *rwb = q->rq_wb; if (rwb) { - del_timer_sync(&rwb->window_timer); + blk_stat_remove_callback(q, rwb->cb); + blk_stat_free_callback(rwb->cb); q->rq_wb = NULL; kfree(rwb); } diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 65f1de519f67..591ff2f4b2ee 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -81,7 +81,7 @@ struct rq_wb { u64 win_nsec; /* default window size */ u64 cur_win_nsec; /* current window size */ - struct timer_list window_timer; + struct blk_stat_callback *cb; s64 sync_issue; void *sync_cookie; diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index e213c5e7500b..270119a501fb 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -294,7 +294,6 @@ struct blk_rq_stat { s32 nr_samples; s32 nr_batch; u64 batch; - s64 time; }; #endif /* __LINUX_BLK_TYPES_H */ diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 5a7da607ca04..1a7dc42a8918 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -40,6 +40,8 @@ struct blkcg_gq; struct blk_flush_queue; struct pr_ops; struct rq_wb; +struct blk_queue_stats; +struct blk_stat_callback; #define BLKDEV_MIN_RQ 4 #define BLKDEV_MAX_RQ 128 /* Default maximum */ @@ -388,6 +390,7 @@ struct request_queue { int nr_rqs[2]; /* # allocated [a]sync rqs */ int nr_rqs_elvpriv; /* # allocated rqs w/ elvpriv */ + struct blk_queue_stats *stats; struct rq_wb *rq_wb; /* @@ -505,8 +508,6 @@ struct request_queue { unsigned int nr_sorted; unsigned int in_flight[2]; - struct blk_rq_stat rq_stats[2]; - /* * Number of active block driver functions for which blk_drain_queue() * must wait. Must be incremented around functions that unlock the @@ -516,6 +517,10 @@ struct request_queue { unsigned int rq_timeout; int poll_nsec; + + struct blk_stat_callback *poll_cb; + struct blk_rq_stat poll_stat[2]; + struct timer_list timeout; struct work_struct timeout_work; struct list_head timeout_list; @@ -611,6 +616,7 @@ struct request_queue { #define QUEUE_FLAG_DAX 26 /* device supports DAX */ #define QUEUE_FLAG_STATS 27 /* track rq completion times */ #define QUEUE_FLAG_RESTART 28 /* queue needs restart at completion */ +#define QUEUE_FLAG_POLL_STATS 29 /* collecting stats for hybrid polling */ #define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ (1 << QUEUE_FLAG_STACKABLE) | \ |