linux-kernel - Re: [PATCH v3 2/6] exit: hoist get_pid() in release_task() outside of tasklist

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Message-ID: <CAGudoHGXR-vnYm-wMs5c8EE448UeuEps3ecrf_g22Mw=9oQtLQ@mail.gmail.com>
Date: Mon, 3 Feb 2025 20:35:47 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>, Mateusz Guzik <mjguzik@...il.com>, ebiederm@...ssion.com, 
	oleg@...hat.com, brauner@...nel.org, akpm@...ux-foundation.org, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/6] exit: hoist get_pid() in release_task() outside of tasklist_lock

On Mon, Feb 3, 2025 at 8:27 PM Liam R. Howlett <Liam.Howlett@...cle.com> wrote:
>
> * Mateusz Guzik <mjguzik@...il.com> [250201 11:31]:
> > Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
>
> Change log is a bit sparse?  I get that the subject spells out what is
> done, but anything to say here at all?  Reduces lock contention by
> reducing lock time or something?  Maybe even some numbers you have in
> the cover letter?
>

I did not measure this bit *specifically*.

As one can expect get_pid issues an atomic and that's slow. And since
it can happen *prior* to taking the global lock it seems like an
obvious little nit to sort out.

I would argue the change is self-explanatory given the cover-letter.

-- 
Mateusz Guzik <mjguzik gmail.com>