linux-kernel - Re: [PATCH v3] sched/core: add forced idle accounting for cgroups

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Message-ID: <Yrl1Tdds6g7h60F3@mtj.duckdns.org>
Date:   Mon, 27 Jun 2022 18:15:57 +0900
From:   Tejun Heo <tj@...nel.org>
To:     Josh Don <joshdon@...gle.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        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,
        Cruz Zhao <CruzZhao@...ux.alibaba.com>
Subject: Re: [PATCH v3] sched/core: add forced idle accounting for cgroups

Hello,

On Tue, Jun 21, 2022 at 04:44:43PM -0700, Josh Don wrote:
> 4feee7d1260 previously added per-task forced idle accounting. This patch
> extends this to also include cgroups.
> 
> rstat is used for cgroup accounting, except for the root, which uses
> kcpustat in order to bypass the need for doing an rstat flush when
> reading root stats.
> 
> Only cgroup v2 is supported. Similar to the task accounting, the cgroup
> accounting requires that schedstats is enabled.

Generally looks fine from cgroup side. One nitpick follow.

> +	seq_printf(seq, "forceidle_usec %llu\n", forceidle_time);

Would it make sense to namespace the name to reflect the fact that
this is tied to core scheduling? e.g. something like
core.force_idle_usec (and yeah, underscore between words, please). I
kinda hate that the feature is named "core". The word is so
overloaded.

Thanks.

-- 
tejun