From: Shaohua Li <shli@fb.com>
Date: Fri, 4 Nov 2016 00:03:54 +0000 (-0700)
Subject: blk-mq: immediately dispatch big size request
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=600271d9000027c013c01be87cbb90a5a18c5c3f;p=linux-beck.git

blk-mq: immediately dispatch big size request

This is corresponding part for blk-mq. Disk with multiple hardware
queues doesn't need this as we only hold 1 request at most.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8d3de5bd4d6f..077c2416a955 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1453,13 +1453,18 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
 	 */
 	plug = current->plug;
 	if (plug) {
+		struct request *last = NULL;
+
 		blk_mq_bio_to_request(rq, bio);
 		if (!request_count)
 			trace_block_plug(q);
+		else
+			last = list_entry_rq(plug->mq_list.prev);
 
 		blk_mq_put_ctx(data.ctx);
 
-		if (request_count >= BLK_MAX_REQUEST_COUNT) {
+		if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
+		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
 			blk_flush_plug_list(plug, false);
 			trace_block_plug(q);
 		}