Commit b2097bd2 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

block: mq-deadline: Reduce lock contention 



blk_mq_free_requests() calls dd_finish_request() indirectly. Prevent
nested locking of dd->lock and dd->zone_lock by moving the code for
freeing requests.

Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230517174230.897144-9-bvanassche@acm.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 3b463cbe

block/mq-deadline.c

+6 −6
Original line number Diff line number Diff line
@@ -757,7 +757,7 @@ static bool dd_bio_merge(struct request_queue *q, struct bio *bio, 
 * add rq to rbtree and fifo

 */

static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,

			      blk_insert_t flags)

			      blk_insert_t flags, struct list_head *free)

{

	struct request_queue *q = hctx->queue;

	struct deadline_data *dd = q->elevator->elevator_data;
@@ -766,7 +766,6 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, 
	u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);

	struct dd_per_prio *per_prio;

	enum dd_prio prio;

	LIST_HEAD(free);



	lockdep_assert_held(&dd->lock);
@@ -783,10 +782,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, 
		rq->elv.priv[0] = (void *)(uintptr_t)1;

	}



	if (blk_mq_sched_try_insert_merge(q, rq, &free)) {

		blk_mq_free_requests(&free);

	if (blk_mq_sched_try_insert_merge(q, rq, free))

		return;

	}



	trace_block_rq_insert(rq);
@@ -819,6 +816,7 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, 
{

	struct request_queue *q = hctx->queue;

	struct deadline_data *dd = q->elevator->elevator_data;

	LIST_HEAD(free);



	spin_lock(&dd->lock);

	while (!list_empty(list)) {
@@ -826,9 +824,11 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, 


		rq = list_first_entry(list, struct request, queuelist);

		list_del_init(&rq->queuelist);

		dd_insert_request(hctx, rq, flags);

		dd_insert_request(hctx, rq, flags, &free);

	}

	spin_unlock(&dd->lock);



	blk_mq_free_requests(&free);

}



/* Callback from inside blk_mq_rq_ctx_init(). */