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block cfq: don't use atomic_t for cfq_queue

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cfq_queue->ref is used with queue_lock hold, so ref doesn't need to be an atomic
and atomic operation is slower.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Shaohua Li 2011-01-07 08:46:59 +01:00 committed by Jens Axboe
parent b7908c1035
commit 30d7b9448f
1 changed files with 16 additions and 11 deletions
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27
block/cfq-iosched.c
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@ -96,7 +96,7 @@ struct cfq_rb_root {
*/
struct cfq_queue {
/* reference count */
atomic_t ref;
int ref;
/* various state flags, see below */
unsigned int flags;
/* parent cfq_data */
@ -2025,7 +2025,7 @@ static int cfqq_process_refs(struct cfq_queue *cfqq)
int process_refs, io_refs;
io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
process_refs = atomic_read(&cfqq->ref) - io_refs;
process_refs = cfqq->ref - io_refs;
BUG_ON(process_refs < 0);
return process_refs;
}
@ -2065,10 +2065,10 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
*/
if (new_process_refs >= process_refs) {
cfqq->new_cfqq = new_cfqq;
atomic_add(process_refs, &new_cfqq->ref);
new_cfqq->ref += process_refs;
} else {
new_cfqq->new_cfqq = cfqq;
atomic_add(new_process_refs, &cfqq->ref);
cfqq->ref += new_process_refs;
}
}
@ -2532,9 +2532,10 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
struct cfq_data *cfqd = cfqq->cfqd;
struct cfq_group *cfqg, *orig_cfqg;
BUG_ON(atomic_read(&cfqq->ref) <= 0);
BUG_ON(cfqq->ref <= 0);
if (!atomic_dec_and_test(&cfqq->ref))
cfqq->ref--;
if (cfqq->ref)
return;
cfq_log_cfqq(cfqd, cfqq, "put_queue");
@ -2837,7 +2838,7 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
RB_CLEAR_NODE(&cfqq->p_node);
INIT_LIST_HEAD(&cfqq->fifo);
atomic_set(&cfqq->ref, 0);
cfqq->ref = 0;
cfqq->cfqd = cfqd;
cfq_mark_cfqq_prio_changed(cfqq);
@ -2973,11 +2974,11 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
* pin the queue now that it's allocated, scheduler exit will prune it
*/
if (!is_sync && !(*async_cfqq)) {
atomic_inc(&cfqq->ref);
cfqq->ref++;
*async_cfqq = cfqq;
}
atomic_inc(&cfqq->ref);
cfqq->ref++;
return cfqq;
}
@ -3679,7 +3680,7 @@ new_queue:
}
cfqq->allocated[rw]++;
atomic_inc(&cfqq->ref);
cfqq->ref++;
spin_unlock_irqrestore(q->queue_lock, flags);
@ -3860,6 +3861,10 @@ static void *cfq_init_queue(struct request_queue *q)
if (!cfqd)
return NULL;
/*
* Don't need take queue_lock in the routine, since we are
* initializing the ioscheduler, and nobody is using cfqd
*/
cfqd->cic_index = i;
/* Init root service tree */
@ -3899,7 +3904,7 @@ static void *cfq_init_queue(struct request_queue *q)
* will not attempt to free it.
*/
cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
atomic_inc(&cfqd->oom_cfqq.ref);
cfqd->oom_cfqq.ref++;
cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
INIT_LIST_HEAD(&cfqd->cic_list);