linux-kernel - Re: [PATCH v2 1/3] sched/fair: Remove unnecessary goto in update_sd_lb

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Message-ID: <CAKfTPtCtqOAgSkXFrm918MCUMR8Z4KuTBGxGvS0E0Bmqg6mkYQ@mail.gmail.com>
Date: Sun, 4 Feb 2024 12:44:18 +0100
From: Vincent Guittot <vincent.guittot@...aro.org>
To: David Vernet <void@...ifault.com>
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 1/3] sched/fair: Remove unnecessary goto in update_sd_lb_stats()

On Sun, 4 Feb 2024 at 05:46, David Vernet <void@...ifault.com> wrote:
>
> In update_sd_lb_stats(), when we're iterating over the sched groups that
> comprise a sched domain, we're skipping the call to
> update_sd_pick_busiest() for the sched group that contains the local /
> destination CPU. We use a goto to skip the call, but we could just as
> easily check !local_group, as there's no other logic that we need to
> skip with the goto. Let's remove the goto, and check for !local_group in
> the if statement instead.
>
> Reviewed-by: Valentin Schneider <vschneid@...hat.com>
> Signed-off-by: David Vernet <void@...ifault.com>

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

> ---
>  kernel/sched/fair.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index b803030c3a03..e7519ea434b1 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -10578,16 +10578,11 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
>
>                 update_sg_lb_stats(env, sds, sg, sgs, &sg_status);
>
> -               if (local_group)
> -                       goto next_group;
> -
> -
> -               if (update_sd_pick_busiest(env, sds, sg, sgs)) {
> +               if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
>                         sds->busiest = sg;
>                         sds->busiest_stat = *sgs;
>                 }
>
> -next_group:
>                 /* Now, start updating sd_lb_stats */
>                 sds->total_load += sgs->group_load;
>                 sds->total_capacity += sgs->group_capacity;
> --
> 2.43.0
>