linux-kernel - Re: [PATCH v2 1/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain

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Date: Mon, 1 Apr 2024 12:23:43 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Vitalii Bursov <vitaly@...sov.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
	Juri Lelli <juri.lelli@...hat.com>, Dietmar Eggemann <dietmar.eggemann@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Daniel Bristot de Oliveira <bristot@...hat.com>, Valentin Schneider <vschneid@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] sched/fair: allow disabling sched_balance_newidle
 with sched_relax_domain_level

On Sun, 31 Mar 2024 at 18:02, Vitalii Bursov <vitaly@...sov.com> wrote:
>
> Change relax_domain_level checks so that it would be possible
> to include or exclude all domains from newidle balancing.
>
> This matches the behavior described in the documentation:
>   -1   no request. use system default or follow request of others.
>    0   no search.
>    1   search siblings (hyperthreads in a core).
>
> "2" enables levels 0 and 1, level_max excludes the last (level_max)
> level, and level_max+1 includes all levels.
>
> Fixes: 9ae7ab20b483 ("sched/topology: Don't set SD_BALANCE_WAKE on cpuset domain relax")
> Signed-off-by: Vitalii Bursov <vitaly@...sov.com>

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

> ---
>  kernel/cgroup/cpuset.c  | 2 +-
>  kernel/sched/topology.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 4237c8748..da24187c4 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -2948,7 +2948,7 @@ bool current_cpuset_is_being_rebound(void)
>  static int update_relax_domain_level(struct cpuset *cs, s64 val)
>  {
>  #ifdef CONFIG_SMP
> -       if (val < -1 || val >= sched_domain_level_max)
> +       if (val < -1 || val > sched_domain_level_max + 1)
>                 return -EINVAL;
>  #endif
>
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 63aecd2a7..67a777b31 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -1475,7 +1475,7 @@ static void set_domain_attribute(struct sched_domain *sd,
>         } else
>                 request = attr->relax_domain_level;
>
> -       if (sd->level > request) {
> +       if (sd->level >= request) {
>                 /* Turn off idle balance on this domain: */
>                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
>         }
> --
> 2.20.1
>