RE: [PATCH 1/3] block: Requeue req as head if driver touched it

[Christian Löhle]

Jens could you consider this patch?
As far as I can see Barts series has not been merged in any form that would fix my problem and even if it does, requeuing RQF_DONTPREP as head seems on par at worst and a performance improvement at best.


-----Original Message-----
From: Christian Löhle 
Sent: Mittwoch, 26. Oktober 2022 09:29
To: axboe@xxxxxxxxx; ulf.hansson@xxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; 'linux-block@xxxxxxxxxxxxxxx' <linux-block@xxxxxxxxxxxxxxx>
Cc: 'Avri Altman' <Avri.Altman@xxxxxxx>; adrian.hunter@xxxxxxxxx; vincent.whitchurch@xxxxxxxx; 'Christian Löhle' <CLoehle@xxxxxxxxxxxxxx>
Subject: [PATCH 1/3] block: Requeue req as head if driver touched it

In case the driver set RQF_DONTPREP flag, requeue the request as head as it is likely that the backing storage already had a request to an adjacent region, so getting the requeued request out as soon as possible may give us some performance benefit.

Signed-off-by: Christian Loehle <cloehle@xxxxxxxxxxxxxx>
---
 block/blk-mq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c index 33292c01875d..d863c826fb23 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1429,7 +1429,7 @@ static void blk_mq_requeue_work(struct work_struct *work)
 		 * merge.
 		 */
 		if (rq->rq_flags & RQF_DONTPREP)
-			blk_mq_request_bypass_insert(rq, false, false);
+			blk_mq_request_bypass_insert(rq, true, false);
 		else
 			blk_mq_sched_insert_request(rq, true, false, false);
 	}
--
2.37.3

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