linux-kernel - Re: [PATCHv5 1/1] block: introduce content activity based ioprio

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Message-ID: <b8be6eb7-05de-49a0-bdc0-b4d16dfe2966@kernel.org>
Date: Tue, 30 Jan 2024 22:53:45 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Zhaoyang Huang <huangzhaoyang@...il.com>
Cc: "zhaoyang.huang" <zhaoyang.huang@...soc.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Jens Axboe <axboe@...nel.dk>,
 Matthew Wilcox <willy@...radead.org>, Yu Zhao <yuzhao@...gle.com>,
 Niklas Cassel <niklas.cassel@....com>,
 "Martin K . Petersen" <martin.petersen@...cle.com>,
 Hannes Reinecke <hare@...e.de>, Linus Walleij <linus.walleij@...aro.org>,
 linux-mm@...ck.org, linux-block@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 steve.kang@...soc.com
Subject: Re: [PATCHv5 1/1] block: introduce content activity based ioprio

On 1/30/24 22:28, Zhaoyang Huang wrote:
>> That information does not belong to the ioprio. And which scheduler acts on a
>> number of pages anyway ? The scheduler sees requests and BIOs. It can determine
>> the number of pages they have if that is an information it needs to make
>> scheduling decisison. Using ioprio to pass that information down is a dirty hack.
> No. IO scheduler acts on IOPRIO_CLASS which is transferred from the
> page's activity by the current method. I will implement another
> version of iterating pages before submit_bio and feed back to the list

Then why are you modifying the ioprio user API to add the 7 bits of activity ?
If the scheduler only needs the priority class, then only set that and do not
touch the user facing API.

-- 
Damien Le Moal
Western Digital Research