linux-kernel - Re: [PATCH v2 09/10] sched/psi: per-cgroup PSI stats disable/re-enable interface

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Date:   Mon, 15 Aug 2022 15:23:30 +0200
From:   Michal Koutný <mkoutny@...e.com>
To:     Chengming Zhou <zhouchengming@...edance.com>
Cc:     hannes@...xchg.org, tj@...nel.org, corbet@....net,
        surenb@...gle.com, mingo@...hat.com, peterz@...radead.org,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, cgroups@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        songmuchun@...edance.com
Subject: Re: [PATCH v2 09/10] sched/psi: per-cgroup PSI stats
 disable/re-enable interface

On Fri, Aug 12, 2022 at 08:36:17PM +0800, Chengming Zhou <zhouchengming@...edance.com> wrote:
> Could you help take a look if there is anything to improve?

Thanks, just a little nit.

> +       The reason this control attribute exists is that PSI accounts stalls for
> +       each cgroup separately and aggregates it at each level of the hierarchy.
> +       This may cause non-negligible overhead for some workloads when under
> +       deep level of the hierarchy, in which case this control attribute can
> +       be used to disable PSI accounting in the cgroups.

s/in the cgroups/in the non-leaf cgroups/
or
s/in the cgroups/in the uninteresting cgroups/

(I'm concerned that it may result in lots of disabling if you want the
performance. I'll expand on it in 2nd subthread.)

Michal