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Date: Fri, 11 Nov 2022 11:30:23 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Christian Löhle <CLoehle@...erstone.com>
Cc: "axboe@...nel.dk" <axboe@...nel.dk>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
Avri Altman <Avri.Altman@....com>,
"adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"vincent.whitchurch@...s.com" <vincent.whitchurch@...s.com>
Subject: Re: [PATCH 1/3] block: Requeue req as head if driver touched it
On Wed, 26 Oct 2022 at 09:30, Christian Löhle <CLoehle@...erstone.com> wrote:
>
> 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.
This is a bit handwavy to me. Would you mind extending this with a
small concrete example, to better understand the benefit?
>
> Signed-off-by: Christian Loehle <cloehle@...erstone.com>
Other than the above nitpick, I can't think of any obvious unwanted
side-effects this could have. So, feel free to add:
Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
Kind regards
Uffe
> ---
> 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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