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

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Message-ID: <20250512123626.GB45370@system.software.com>
Date: Mon, 12 May 2025 21:36:26 +0900
From: Byungchul Park <byungchul@...com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: Pavel Begunkov <asml.silence@...il.com>, 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 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.

	Byungchul

> --
> Thanks,
> Mina