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block: make queue stat accounting a reference 

kyber turns on IO statistics when it is loaded on a queue, which means
that even if kyber is then later unloaded, we're still stuck with stats
enabled on the queue.

Change the account enabled from a bool to an int, and pair the enable call
with the equivalent disable call. This ensures that stats gets turned off
again appropriately.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-12-14 17:23:05 -07:00
parent 0ba4566cd8
commit 68497092bd
3 changed files with 18 additions and 5 deletions
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21
block/blk-stat.c
View File

@ -15,7 +15,7 @@
struct blk_queue_stats {
struct list_head callbacks;
spinlock_t lock;
bool enable_accounting;
int accounting;
};
void blk_rq_stat_init(struct blk_rq_stat *stat)
@ -161,7 +161,7 @@ void blk_stat_remove_callback(struct request_queue *q,
spin_lock_irqsave(&q->stats->lock, flags);
list_del_rcu(&cb->list);
if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting)
if (list_empty(&q->stats->callbacks) && !q->stats->accounting)
blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
spin_unlock_irqrestore(&q->stats->lock, flags);
@ -184,13 +184,24 @@ void blk_stat_free_callback(struct blk_stat_callback *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)
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);
q->stats->enable_accounting = true;
blk_queue_flag_set(QUEUE_FLAG_STATS, q);
if (!q->stats->accounting++)
blk_queue_flag_set(QUEUE_FLAG_STATS, q);
spin_unlock_irqrestore(&q->stats->lock, flags);
}
EXPORT_SYMBOL_GPL(blk_stat_enable_accounting);
@ -205,7 +216,7 @@ struct blk_queue_stats *blk_alloc_queue_stats(void)
INIT_LIST_HEAD(&stats->callbacks);
spin_lock_init(&stats->lock);
stats->enable_accounting = false;
stats->accounting = 0;
return stats;
}

1
block/blk-stat.h
View File

@ -70,6 +70,7 @@ void blk_stat_add(struct request *rq, u64 now);
/* record time/size info in request but not add a callback */
void blk_stat_enable_accounting(struct request_queue *q);
void blk_stat_disable_accounting(struct request_queue *q);
/**
* blk_stat_alloc_callback() - Allocate a block statistics callback.

1
block/kyber-iosched.c
View File

@ -433,6 +433,7 @@ static void kyber_exit_sched(struct elevator_queue *e)
int i;
del_timer_sync(&kqd->timer);
blk_stat_disable_accounting(kqd->q);
for (i = 0; i < KYBER_NUM_DOMAINS; i++)
sbitmap_queue_free(&kqd->domain_tokens[i]);