diff options
| author | Shaohua Li <shaohua.li@intel.com> | 2011-01-07 08:48:28 +0100 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2011-01-07 08:48:28 +0100 |
| commit | 329a67815b596d23daf0caa588ae0800e925320f (patch) | |
| tree | 5fcf8a7c4a4d43b2cc7dc220d6bb25bdf27d153f /block | |
| parent | 30d7b9448f03f2c82d0fd44738674cc156a8ce0a (diff) | |
| download | lwn-329a67815b596d23daf0caa588ae0800e925320f.tar.gz lwn-329a67815b596d23daf0caa588ae0800e925320f.zip | |
block cfq: don't use atomic_t for cfq_group
cfq_group->ref is used with queue_lock hold, the only exception is
cfq_set_request, which looks like a bug to me, 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>
Diffstat (limited to 'block')
| -rw-r--r-- | block/cfq-iosched.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 4cb4cf73ac00..f083bda30546 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -207,7 +207,7 @@ struct cfq_group { struct blkio_group blkg; #ifdef CONFIG_CFQ_GROUP_IOSCHED struct hlist_node cfqd_node; - atomic_t ref; + int ref; #endif /* number of requests that are on the dispatch list or inside driver */ int dispatched; @@ -1014,7 +1014,7 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create) * elevator which will be dropped by either elevator exit * or cgroup deletion path depending on who is exiting first. */ - atomic_set(&cfqg->ref, 1); + cfqg->ref = 1; /* * Add group onto cgroup list. It might happen that bdi->dev is @@ -1059,7 +1059,7 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) { - atomic_inc(&cfqg->ref); + cfqg->ref++; return cfqg; } @@ -1071,7 +1071,7 @@ static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) cfqq->cfqg = cfqg; /* cfqq reference on cfqg */ - atomic_inc(&cfqq->cfqg->ref); + cfqq->cfqg->ref++; } static void cfq_put_cfqg(struct cfq_group *cfqg) @@ -1079,8 +1079,9 @@ static void cfq_put_cfqg(struct cfq_group *cfqg) struct cfq_rb_root *st; int i, j; - BUG_ON(atomic_read(&cfqg->ref) <= 0); - if (!atomic_dec_and_test(&cfqg->ref)) + BUG_ON(cfqg->ref <= 0); + cfqg->ref--; + if (cfqg->ref) return; for_each_cfqg_st(cfqg, i, j, st) BUG_ON(!RB_EMPTY_ROOT(&st->rb)); @@ -1188,7 +1189,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, cfq_group_service_tree_del(cfqd, cfqq->cfqg); cfqq->orig_cfqg = cfqq->cfqg; cfqq->cfqg = &cfqd->root_group; - atomic_inc(&cfqd->root_group.ref); + cfqd->root_group.ref++; group_changed = 1; } else if (!cfqd->cfq_group_isolation && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) { @@ -3681,12 +3682,12 @@ new_queue: cfqq->allocated[rw]++; cfqq->ref++; - - spin_unlock_irqrestore(q->queue_lock, flags); - rq->elevator_private = cic; rq->elevator_private2 = cfqq; rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg); + + spin_unlock_irqrestore(q->queue_lock, flags); + return 0; queue_fail: @@ -3884,7 +3885,7 @@ static void *cfq_init_queue(struct request_queue *q) * Take a reference to root group which we never drop. This is just * to make sure that cfq_put_cfqg() does not try to kfree root group */ - atomic_set(&cfqg->ref, 1); + cfqg->ref = 1; rcu_read_lock(); cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd, 0); |