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Commit 322731ed authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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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: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 2da8de0b

block/cfq-iosched.c

+12 −16
Original line number Diff line number Diff line
@@ -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;

}