linux-kernel - Re: [PATCH v2] readahead: Correct the start and size in ondemand

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Date:   Thu, 6 Jul 2023 09:32:25 +0800
From:   Yin Fengwei <fengwei.yin@...el.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>, <willy@...radead.org>,
        <akpm@...ux-foundation.org>
CC:     <ackerleytng@...gle.com>, <linux-fsdevel@...r.kernel.org>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <oliver.sang@...el.com>
Subject: Re: [PATCH v2] readahead: Correct the start and size in
 ondemand_readahead()



On 7/6/23 00:52, Mike Kravetz wrote:
> On 07/04/23 09:41, Yin, Fengwei wrote:
>> On 7/4/2023 2:49 AM, Mike Kravetz wrote:
>>> On 06/28/23 12:43, Yin Fengwei wrote:
>>>
>>> Thank you for your detailed analysis!
>>>
>>> When the regression was initially discovered, I sent a patch to revert
>>> commit 9425c591e06a.  Andrew has picked up this change.  And, Andrew has
>>> also picked up this patch.
>> Oh. I didn't notice that you sent revert patch. My understanding is that
>> commit 9425c591e06a is a good change.
>>
>>>
>>> I have not verified yet, but I suspect that this patch is going to cause
>>> a regression because it depends on the behavior of page_cache_next_miss
>>> in 9425c591e06a which has been reverted.
>> Yes. If the 9425c591e06a was reverted, this patch could introduce regression.
>> Which fixing do you prefer? reverting 9425c591e06a or this patch? Then we
>> can suggest to Andrew to take it.
> 
> For now, I suggest we go with the revert.  Why?
> - The revert is already going into stable trees.
> - I may not be remembering correctly, but I seem to recall Matthew
>   mentioning plans to redo/redesign the page cache and possibly
>   readahead code.  If this is the case, then better to keep the legacy
>   behavior for now.  But, I am not sure if this is actually part of any
>   plan or work in progress.
> 
It's fine to me and thanks a lot for detail explanations.


Hi Andrew,
Could you please help to drop this patch? Thanks.


Regards
Yin, Fengwei