blk-mq: apply normal plugging for HDD (3154df26) · Commits · 戴 / test

Some HDD drive may expose multiple hardware queues, such as MegraRaid. Let's apply the normal plugging for such devices because sequential IO may benefit a lot from plug merging. Cc: Bart Van Assche <bvanassche@acm.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Dave Chinner <dchinner@redhat.com> Reviewed-by:

Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by:

Ming Lei <ming.lei@redhat.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -1992,10 +1992,14 @@ static blk_qc_t blk_mq_make_request(struct request_queue q, struct bio bio)
		/* bypass scheduler for flush rq */
		blk_insert_flush(rq);
		blk_mq_run_hw_queue(data.hctx, true);
		} else if (plug && (q->nr_hw_queues == 1 \|\| q->mq_ops->commit_rqs)) {
		} else if (plug && (q->nr_hw_queues == 1 \|\| q->mq_ops->commit_rqs \|\|
		!blk_queue_nonrot(q))) {
		/*
		* Use plugging if we have a ->commit_rqs() hook as well, as
		* we know the driver uses bd->last in a smart fashion.
		*
		* Use normal plugging if this disk is slow HDD, as sequential
		* IO may benefit a lot from plug merging.
		*/
		unsigned int request_count = plug->rq_count;
		struct request *last = NULL;

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