blk-throttle: add a mechanism to estimate IO latency

[karo-tx-linux.git] / block / blk-stat.c

diff --git a/block/blk-stat.c b/block/blk-stat.c
index 188b535cf4d614f6ccb9c579a113132e7e1b5983..e77ec52f5bb51513fc9d7850301ab5bbafe51551 100644 (file)
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -9,12 +9,14 @@
 
 #include "blk-stat.h"
 #include "blk-mq.h"
+#include "blk.h"
 
 #define BLK_RQ_STAT_BATCH      64
 
 struct blk_queue_stats {
        struct list_head callbacks;
        spinlock_t lock;
+       bool enable_accounting;
 };
 
 unsigned int blk_stat_rq_ddir(const struct request *rq)
@@ -96,6 +98,8 @@ void blk_stat_add(struct request *rq)
 
        value = now - blk_stat_time(&rq->issue_stat);
 
+       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)) {
@@ -190,7 +194,7 @@ void blk_stat_remove_callback(struct request_queue *q,
 {
        spin_lock(&q->stats->lock);
        list_del_rcu(&cb->list);
-       if (list_empty(&q->stats->callbacks))
+       if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting)
                clear_bit(QUEUE_FLAG_STATS, &q->queue_flags);
        spin_unlock(&q->stats->lock);
 
@@ -215,6 +219,14 @@ void blk_stat_free_callback(struct blk_stat_callback *cb)
 }
 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;
+       set_bit(QUEUE_FLAG_STATS, &q->queue_flags);
+       spin_unlock(&q->stats->lock);
+}
+
 struct blk_queue_stats *blk_alloc_queue_stats(void)
 {
        struct blk_queue_stats *stats;
@@ -225,6 +237,7 @@ struct blk_queue_stats *blk_alloc_queue_stats(void)
 
        INIT_LIST_HEAD(&stats->callbacks);
        spin_lock_init(&stats->lock);
+       stats->enable_accounting = false;
 
        return stats;
 }