linux-kernel - Re: [RFC 00/19] Split netmem from struct page

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Message-ID: <b18480f2-30c9-4598-9660-c2ca317c5de2@gmail.com>
Date: Mon, 12 May 2025 13:59:21 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Byungchul Park <byungchul@...com>, Mina Almasry <almasrymina@...gle.com>
Cc: willy@...radead.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org, kernel_team@...ynix.com,
 kuba@...nel.org, ilias.apalodimas@...aro.org, harry.yoo@...cle.com,
 hawk@...nel.org, akpm@...ux-foundation.org, ast@...nel.org,
 daniel@...earbox.net, davem@...emloft.net, john.fastabend@...il.com,
 andrew+netdev@...n.ch, edumazet@...gle.com, pabeni@...hat.com,
 vishal.moola@...il.com
Subject: Re: [RFC 00/19] Split netmem from struct page

On 5/12/25 13:36, Byungchul Park wrote:
> On Fri, May 09, 2025 at 07:09:16AM -0700, Mina Almasry wrote:
>> On Fri, May 9, 2025 at 4:51 AM Byungchul Park <byungchul@...com> wrote:
>>>
>>> The MM subsystem is trying to reduce struct page to a single pointer.
>>> The first step towards that is splitting struct page by its individual
>>> users, as has already been done with folio and slab.  This patchset does
>>> that for netmem which is used for page pools.
>>>
>>> Matthew Wilcox tried and stopped the same work, you can see in:
>>>
>>>     https://lore.kernel.org/linux-mm/20230111042214.907030-1-willy@infradead.org/
>>>
>>> Mina Almasry already has done a lot fo prerequisite works by luck, he
>>> said :).  I stacked my patches on the top of his work e.i. netmem.
>>>
>>> I focused on removing the page pool members in struct page this time,
>>> not moving the allocation code of page pool from net to mm.  It can be
>>> done later if needed.
>>>
>>> There are still a lot of works to do, to remove the dependency on struct
>>> page in the network subsystem.  I will continue to work on this after
>>> this base patchset is merged.
>>>
>>> This patchset is based on mm tree's mm-unstable branch.
>>>
>>
>> This series largely looks good to me, but a couple of things:
>>
>> - For deep changes like this to the page_pool, I think we need a
>> before/after run to Jesper's currently out-of-tree benchmark to see
>> any regressions:
>> https://lore.kernel.org/netdev/20250309084118.3080950-1-almasrymina@google.com/
> 
> Sure.  I will check it.
> 
>> - Also please CC Pavel on iterations related to netmem/net_iov, they
>> are reusing that in io_uring code for iouring rx rc as well.
> 
> I will.  Thank you.

Mina, thanks for CC'ing. And since it's touching io_uring, future
versions need to CC it as well.

-- 
Pavel Begunkov