blk-mq: use plug for devices that implement ->commits_rqs() (b2c5d16b) · Commits · e / devices / android_kernel_fairphone_FP5

If we have that hook, we know the driver handles bd->last == true in a smart fashion. If it does, even for multiple hardware queues, it's a good idea to flush batches of requests to the device, if we have batches of requests from the submitter. Reviewed-by:

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

Christoph Hellwig <hch@lst.de> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -1945,7 +1945,11 @@ 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) {
		} else if (plug && (q->nr_hw_queues == 1 \|\| q->mq_ops->commit_rqs)) {
		/*
		* Use plugging if we have a ->commit_rqs() hook as well, as
		* we know the driver uses bd->last in a smart fashion.
		*/
		unsigned int request_count = plug->rq_count;
		struct request *last = NULL;