Commit 3c67d44d authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add mq_ops->queue_rqs hook 



If we have a list of requests in our plug list, send it to the driver in
one go, if possible. The driver must set mq_ops->queue_rqs() to support
this, if not the usual one-by-one path is used.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent fcade2ce

block/blk-mq.c

+23 −3
Original line number Diff line number Diff line
@@ -2553,6 +2553,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) 
{

	struct blk_mq_hw_ctx *this_hctx;

	struct blk_mq_ctx *this_ctx;

	struct request *rq;

	unsigned int depth;

	LIST_HEAD(list);
@@ -2561,7 +2562,28 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) 
	plug->rq_count = 0;



	if (!plug->multiple_queues && !plug->has_elevator && !from_schedule) {

		struct request_queue *q = rq_list_peek(&plug->mq_list)->q;

		struct request_queue *q;



		rq = rq_list_peek(&plug->mq_list);

		q = rq->q;



		/*

		 * Peek first request and see if we have a ->queue_rqs() hook.

		 * If we do, we can dispatch the whole plug list in one go. We

		 * already know at this point that all requests belong to the

		 * same queue, caller must ensure that's the case.

		 *

		 * Since we pass off the full list to the driver at this point,

		 * we do not increment the active request count for the queue.

		 * Bypass shared tags for now because of that.

		 */

		if (q->mq_ops->queue_rqs &&

		    !(rq->mq_hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {

			blk_mq_run_dispatch_ops(q,

				q->mq_ops->queue_rqs(&plug->mq_list));

			if (rq_list_empty(plug->mq_list))

				return;

		}



		blk_mq_run_dispatch_ops(q,

				blk_mq_plug_issue_direct(plug, false));
@@ -2573,8 +2595,6 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) 
	this_ctx = NULL;

	depth = 0;

	do {

		struct request *rq;



		rq = rq_list_pop(&plug->mq_list);



		if (!this_hctx) {

include/linux/blk-mq.h

+8 −0
Original line number Diff line number Diff line
@@ -492,6 +492,14 @@ struct blk_mq_ops { 
	 */

	void (*commit_rqs)(struct blk_mq_hw_ctx *);



	/**

	 * @queue_rqs: Queue a list of new requests. Driver is guaranteed

	 * that each request belongs to the same queue. If the driver doesn't

	 * empty the @rqlist completely, then the rest will be queued

	 * individually by the block layer upon return.

	 */

	void (*queue_rqs)(struct request **rqlist);



	/**

	 * @get_budget: Reserve budget before queue request, once .queue_rq is

	 * run, it is driver's responsibility to release the