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Message-ID: <f30ec7fe7d834c1d8e116508500110cf@hyperstone.com>
Date: Wed, 26 Oct 2022 07:30:37 +0000
From: Christian Löhle <CLoehle@...erstone.com>
To: "axboe@...nel.dk" <axboe@...nel.dk>,
"ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
"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>
CC: Avri Altman <Avri.Altman@....com>,
"adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"vincent.whitchurch@...s.com" <vincent.whitchurch@...s.com>,
Christian Löhle <CLoehle@...erstone.com>
Subject: [PATCH 0/3] mmc: Improve block layer requeueing behavior
Mmcblk relies on block layer requeueing to fulfill some requests under
certain conditions. Improve the handling to get nicely ordered requests.
Using the terms a bit loosely to get a point across:
Current behavior for 512 blksz and max_blk_count = 1 the scenario would
be as follows:
- request for page 0 lba 0 to 7
- request for page 1 lba 8 to 15
- request for page 2 lba 16 to 23
- request for page 3 lba 24 to 31
mmcblk modifies data->blocks = 1 for each and requeues,
this leads to:
Access lba 0
Access lba 8
Access lba 16
Access lba 24
Access lba 1 (1. Requeue for page 0)
Access lba 9 (1. Requeue for page 1)
Access lba 17 (1. Requeue for page 2)
Access lba 25 (1. Requeue for page 3)
Access lba 2 (2. Requeue for page 0)
...
Of course we would rather have lbas consecutive.
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