linux-kernel - Re: [PATCH v3 0/7] Split a folio to any lower order folios

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Message-ID: <FF718BD8-8A54-47AC-B75F-928ECA42BB79@nvidia.com>
Date: Tue, 13 Feb 2024 08:46:10 -0500
From: Zi Yan <ziy@...dia.com>
To: "\"Pankaj Raghav (Samsung)\"" <kernel@...kajraghav.com>
Cc: "\"Matthew Wilcox (Oracle)\"" <willy@...radead.org>,
 Yang Shi <shy828301@...il.com>, Yu Zhao <yuzhao@...gle.com>,
 linux-mm@...ck.org,
 "\"Kirill A . Shutemov\"" <kirill.shutemov@...ux.intel.com>,
 Ryan Roberts <ryan.roberts@....com>,
 "Michal Koutný" <mkoutny@...e.com>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 "\"Zach O'Keefe\"" <zokeefe@...gle.com>,
 Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org,
 cgroups@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 linux-kselftest@...r.kernel.org, mcgrof@...nel.org, gost.dev@...sung.com
Subject: Re: [PATCH v3 0/7] Split a folio to any lower order folios

On 13 Feb 2024, at 7:30, Pankaj Raghav (Samsung) wrote:

> Hi Zi yan,
>
>> From: Zi Yan <ziy@...dia.com>
>>
>> Hi all,
>>
>> File folio supports any order and people would like to support flexible orders
>> for anonymous folio[1] too. Currently, split_huge_page() only splits a huge
>> page to order-0 pages, but splitting to orders higher than 0 is also useful.
>> This patchset adds support for splitting a huge page to any lower order pages
>> and uses it during file folio truncate operations.
>>
>
> I recently posted patches to enable block size > page size(Large Block
> Sizes) in XFS[1].
> The main idea of LBS is to have a notion of minimum order in the
> page cache that corresponds to the filesystem block size.
>
> Ability to split a folio based on a given order is something that would
> definitely optimize the LBS implementation.
>
> The current implementation refuses to split a large folio if it has a
> minimum order set in the page cache [2]. What we would like to have instead
> is to split it based on the minimum order. The main use is of course being
> able to free some folios during partial truncate operation.
>
> Your patch was also suggested by willy during our LPC talk[3].
>
> I tried rebasing your patch and there were a lot of non-trivial conflicts.
> Is there any plans on sending a new version?

Sure. I am going to rebase and send a new version out.

>
>
> [1] https://lore.kernel.org/linux-xfs/20240213093713.1753368-1-kernel@pankajraghav.com/
> [2] https://lore.kernel.org/linux-xfs/20240213093713.1753368-9-kernel@pankajraghav.com/
> [3] https://youtu.be/ar72r5Xf7x4?si=XDb-g7SSIgS-5TkP&t=1457
>
> --
> Pankaj

--
Best Regards,
Yan, Zi

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