Commit 25c4b5e0 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-ioprio: don't set bio priority if not needed 



We don't need to write to the bio if:

1) No ioprio value has ever been assigned to the blkcg
2) We wouldn't anyway, depending on bio and blkcg IO priority

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1e9c2303

block/blk-ioprio.c

+10 −3
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ struct ioprio_blkg { 
struct ioprio_blkcg {

	struct blkcg_policy_data cpd;

	enum prio_policy	 prio_policy;

	bool			 prio_set;

};



static inline struct ioprio_blkg *pd_to_ioprio(struct blkg_policy_data *pd)
@@ -112,7 +113,7 @@ static ssize_t ioprio_set_prio_policy(struct kernfs_open_file *of, char *buf, 
	if (ret < 0)

		return ret;

	blkcg->prio_policy = ret;



	blkcg->prio_set = true;

	return nbytes;

}
@@ -190,6 +191,10 @@ static void blkcg_ioprio_track(struct rq_qos *rqos, struct request *rq, 
			       struct bio *bio)

{

	struct ioprio_blkcg *blkcg = ioprio_blkcg_from_bio(bio);

	u16 prio;



	if (!blkcg->prio_set)

		return;



	/*

	 * Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
@@ -199,8 +204,10 @@ static void blkcg_ioprio_track(struct rq_qos *rqos, struct request *rq, 
	 * bio I/O priority is not modified. If the bio I/O priority equals

	 * IOPRIO_CLASS_NONE, the cgroup I/O priority is assigned to the bio.

	 */

	bio->bi_ioprio = max_t(u16, bio->bi_ioprio,

	prio = max_t(u16, bio->bi_ioprio,

			IOPRIO_PRIO_VALUE(blkcg->prio_policy, 0));

	if (prio > bio->bi_ioprio)

		bio->bi_ioprio = prio;

}



static void blkcg_ioprio_exit(struct rq_qos *rqos)