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-rw-r--r--block/blk-stat.c250
1 files changed, 250 insertions, 0 deletions
diff --git a/block/blk-stat.c b/block/blk-stat.c
new file mode 100644
index 000000000..da9407b7d
--- /dev/null
+++ b/block/blk-stat.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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;
+ int 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, cpu;
+ 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();
+ cpu = get_cpu();
+ 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 = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket];
+ blk_rq_stat_add(stat, value);
+ }
+ put_cpu();
+ 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;
+}
+
+void blk_stat_add_callback(struct request_queue *q,
+ struct blk_stat_callback *cb)
+{
+ unsigned int bucket;
+ unsigned long flags;
+ 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_irqsave(&q->stats->lock, flags);
+ list_add_tail_rcu(&cb->list, &q->stats->callbacks);
+ blk_queue_flag_set(QUEUE_FLAG_STATS, q);
+ spin_unlock_irqrestore(&q->stats->lock, flags);
+}
+
+void blk_stat_remove_callback(struct request_queue *q,
+ struct blk_stat_callback *cb)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->stats->lock, flags);
+ list_del_rcu(&cb->list);
+ if (list_empty(&q->stats->callbacks) && !q->stats->accounting)
+ blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
+ spin_unlock_irqrestore(&q->stats->lock, flags);
+
+ del_timer_sync(&cb->timer);
+}
+
+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);
+}
+
+void blk_stat_disable_accounting(struct request_queue *q)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->stats->lock, flags);
+ if (!--q->stats->accounting && list_empty(&q->stats->callbacks))
+ blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
+ spin_unlock_irqrestore(&q->stats->lock, flags);
+}
+EXPORT_SYMBOL_GPL(blk_stat_disable_accounting);
+
+void blk_stat_enable_accounting(struct request_queue *q)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->stats->lock, flags);
+ if (!q->stats->accounting++ && list_empty(&q->stats->callbacks))
+ blk_queue_flag_set(QUEUE_FLAG_STATS, q);
+ spin_unlock_irqrestore(&q->stats->lock, flags);
+}
+EXPORT_SYMBOL_GPL(blk_stat_enable_accounting);
+
+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->accounting = 0;
+
+ return stats;
+}
+
+void blk_free_queue_stats(struct blk_queue_stats *stats)
+{
+ if (!stats)
+ return;
+
+ WARN_ON(!list_empty(&stats->callbacks));
+
+ kfree(stats);
+}
+
+bool blk_stats_alloc_enable(struct request_queue *q)
+{
+ struct blk_rq_stat *poll_stat;
+
+ poll_stat = kcalloc(BLK_MQ_POLL_STATS_BKTS, sizeof(*poll_stat),
+ GFP_ATOMIC);
+ if (!poll_stat)
+ return false;
+
+ if (cmpxchg(&q->poll_stat, NULL, poll_stat) != NULL) {
+ kfree(poll_stat);
+ return true;
+ }
+
+ blk_stat_add_callback(q, q->poll_cb);
+ return false;
+}