linux-kernel - Re: [PATCH 0/4] move per-vma lock into vm_area

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Message-ID: <CAJuCfpHpkEYG0=8rarDCQ9V=BhxTA2KCvSwKMwp4kdbpgk7sCw@mail.gmail.com>
Date: Tue, 12 Nov 2024 07:38:09 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: akpm@...ux-foundation.org, willy@...radead.org, liam.howlett@...cle.com, 
	mhocko@...e.com, vbabka@...e.cz, hannes@...xchg.org, mjguzik@...il.com, 
	oliver.sang@...el.com, mgorman@...hsingularity.net, david@...hat.com, 
	peterx@...hat.com, oleg@...hat.com, dave@...olabs.net, paulmck@...nel.org, 
	brauner@...nel.org, dhowells@...hat.com, hdanton@...a.com, hughd@...gle.com, 
	minchan@...gle.com, jannh@...gle.com, shakeel.butt@...ux.dev, 
	souravpanda@...gle.com, pasha.tatashin@...een.com, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH 0/4] move per-vma lock into vm_area_struct

On Tue, Nov 12, 2024 at 1:39 AM Lorenzo Stoakes
<lorenzo.stoakes@...cle.com> wrote:
>
> On Mon, Nov 11, 2024 at 12:55:02PM -0800, Suren Baghdasaryan wrote:
> > Back when per-vma locks were introduces, vm_lock was moved out of
> > vm_area_struct in [1] because of the performance regression caused by
> > false cacheline sharing. Recent investigation [2] revealed that the
> > regressions is limited to a rather old Broadwell microarchitecture and
> > even there it can be mitigated by disabling adjacent cacheline
> > prefetching, see [3].
>
> Sorry to nag + add workload, but could you also add changes to the
> Documentation/mm/process_addrs.rst file to reflect this as part of the
> series? It'd be really cool to have the change as part of your series, so
> when it lands we update the documentation with it.
>
> This change fundamentally changes internals that are documented there so it
> makes sense to :)

Yep, I already prepared the documentation patch to be included in v2.
Sorry for missing it the first time around and thanks for the
reminder.

>
> Thanks!