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

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Message-ID: <2f3gjvg6zwp2xpkhb2e36ux2resnjdtxuinbbgnr57jdqesrm6@oau2dgx63fxy>
Date: Mon, 3 Feb 2025 15:13:39 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: 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

* Mateusz Guzik <mjguzik@...il.com> [250203 14:36]:
> 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.

But when you git blame on the file, you will not see that cover letter.

> 
> -- 
> Mateusz Guzik <mjguzik gmail.com>