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cfq-iosched: move cfq_group determination from cfq_find_alloc_queue() to cfq_get_queue() 

This is necessary for making async cfq_cgroups per-cfq_group instead
of per-cfq_data.  While this change makes cfq_get_queue() perform RCU
locking and look up cfq_group even when it reuses async queue, the
extra overhead is extremely unlikely to be noticeable given that this
is already sitting behind cic->cfqq[] cache and the overall cost of
cfq operation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-08-18 14:55:03 -07:00 committed by Jens Axboe
parent 2da8de0bb7
commit 322731ed0d
1 changed files with 12 additions and 16 deletions
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28
block/cfq-iosched.c
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@ -3641,21 +3641,10 @@ static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) {
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
struct bio *bio)
cfq_find_alloc_queue(struct cfq_data *cfqd, struct cfq_group *cfqg, bool is_sync,
struct cfq_io_cq *cic, struct bio *bio)
{
struct blkcg *blkcg;
struct cfq_queue *cfqq;
struct cfq_group *cfqg;
rcu_read_lock();
blkcg = bio_blkcg(bio);
cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
if (!cfqg) {
cfqq = &cfqd->oom_cfqq;
goto out;
}
cfqq = cic_to_cfqq(cic, is_sync);
@ -3675,8 +3664,6 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
} else
cfqq = &cfqd->oom_cfqq;
}
out:
rcu_read_unlock();
return cfqq;
}
@ -3706,6 +3693,14 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
struct cfq_queue **async_cfqq;
struct cfq_queue *cfqq;
struct cfq_group *cfqg;
rcu_read_lock();
cfqg = cfq_lookup_create_cfqg(cfqd, bio_blkcg(bio));
if (!cfqg) {
cfqq = &cfqd->oom_cfqq;
goto out;
}
if (!is_sync) {
if (!ioprio_valid(cic->ioprio)) {
@ -3719,7 +3714,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
goto out;
}
cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio);
cfqq = cfq_find_alloc_queue(cfqd, cfqg, is_sync, cic, bio);
/*
* pin the queue now that it's allocated, scheduler exit will prune it
@ -3730,6 +3725,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
}
out:
cfqq->ref++;
rcu_read_unlock();
return cfqq;
}