linux-kernel - Re: [PATCH 00/16] blk-mq: introduce new queue attribute asyc

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Message-ID: <8ff85b30-27c5-c980-a1fb-fdbe18329594@huaweicloud.com>
Date: Thu, 14 Aug 2025 16:57:21 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Ming Lei <ming.lei@...hat.com>, Yu Kuai <yukuai1@...weicloud.com>
Cc: axboe@...nel.dk, bvanassche@....org, nilay@...ux.ibm.com, hare@...e.de,
 linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 yi.zhang@...wei.com, yangerkun@...wei.com, johnny.chenyi@...wei.com,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH 00/16] blk-mq: introduce new queue attribute asyc_dpeth

Hi,

在 2025/08/14 16:27, Ming Lei 写道:
> On Thu, Aug 14, 2025 at 04:22:27PM +0800, Yu Kuai wrote:
>> Hi,
>>
>> 在 2025/08/14 15:54, Ming Lei 写道:
>>> On Thu, Aug 14, 2025 at 11:35:06AM +0800, Yu Kuai wrote:
>>>> From: Yu Kuai <yukuai3@...wei.com>
>>>>
>>>> Backgroud and motivation:
>>>>
>>>> At first, we test a performance regression from 5.10 to 6.6 in
>>>> downstream kernel(described in patch 13), the regression is related to
>>>> async_depth in mq-dealine.
>>>>
>>>> While trying to fix this regression, Bart suggests add a new attribute
>>>> to request_queue, and I think this is a good idea because all elevators
>>>> have similar logical, however only mq-deadline allow user to configure
>>>> async_depth. And this is patch 9-16, where the performance problem is
>>>> fixed in patch 13;
>>>>
>>>> Because async_depth is related to nr_requests, while reviewing related
>>>> code, patch 2-7 are cleanups and fixes to nr_reqeusts.
>>>>
>>>> I was planning to send this set for the next merge window, however,
>>>> during test I found the last block pr(6.17-rc1) introduce a regression
>>>> if nr_reqeusts grows, exit elevator will panic, and I fix this by
>>>> patch 1,8.
>>>
>>> Please split the patchset into two:
>>>
>>> - one is for fixing recent regression on updating 'nr_requests', so this
>>>     can be merged to v6.17, and be backport easily for stable & downstream
>>
>> There are actually two regressions, as fixed by patch 5 and patch 8, how
>> about the first patchset for patch 1-8? Are you good with those minor
>> prep cleanup patches?
> 
> Then probably you need to make it into three by adding one extra bug fix for
> `fix elevator depth_updated method`, which follows the philosophy of
> "do one thing, do it better", also helps people to review.

Ok, I'll send patch 5 seperatly since it can solve problem
independently, and then a patchset for nr_requests regression.

Thanks,
Kuai

> 
> Thanks,
> Ming
> 
> 
> .
>