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. Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> --- block/blk-mq.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 9e1045152e45..091557a43d53 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1945,7 +1945,12 @@ 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; -- 2.17.1