linux-kernel - Re: [PATCH v2 3/3] sched/fair: Simplify some logic in update_sd_pick

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Message-ID: <20240205151041.GD120243@maniforge>
Date: Mon, 5 Feb 2024 09:10:41 -0600
From: David Vernet <void@...ifault.com>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: linux-kernel@...r.kernel.org, mingo@...hat.com, peterz@...radead.org,
	juri.lelli@...hat.com, dietmar.eggemann@....com,
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
	bristot@...hat.com, vschneid@...hat.com, kernel-team@...a.com
Subject: Re: [PATCH v2 3/3] sched/fair: Simplify some logic in
 update_sd_pick_busiest()

On Sun, Feb 04, 2024 at 12:48:11PM +0100, Vincent Guittot wrote:
> On Sun, 4 Feb 2024 at 05:46, David Vernet <void@...ifault.com> wrote:
> >
> > When comparing the current struct sched_group with the yet-busiest
> > domain in update_sd_pick_busiest(), if the two groups have the same
> > group type, we're currently doing a bit of unnecessary work for any
> > group >= group_misfit_task. We're comparing the two groups, and then
> > returning only if false (the group in question is not the busiest).
> > Othewise, we break, do an extra unnecessary conditional check that's
> > vacuously false for any group type > group_fully_busy, and then always
> > return true.
> >
> > Let's just return directly in the switch statement instead. This doesn't
> > change the size of vmlinux with llvm 17 (not surprising given that all
> > of this is inlined in load_balance()), but it does shrink load_balance()
> > by 88 bytes on x86. Given that it also improves readability, this seems
> > worth doing.
> >
> > As a bonus, remove an unnecessary goto in update_sd_lb_stats().
> 
> The line above is not relevant to the content of the patch.

Ah, thanks for catching that.

Should I send a v3 of the patch set? Or should I just let whomever
applies remove that line?

> Other than that
> 
> Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>

Thanks,
David

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