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From:   Stephane Eranian <eranian@google.com>
Date:   Wed, 2 Dec 2020 11:47:25 -0800
Message-ID: <CABPqkBR5nCfn756Wb8xQEb9Xse+UQPAbGy969cP4sxO78-Nq4g@mail.gmail.com>
Subject: Re: [RFC 1/2] perf core: Add PERF_COUNT_SW_CGROUP_SWITCHES event
To:     Andi Kleen <ak@linux.intel.com>
Cc:     Namhyung Kim <namhyung@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Ian Rogers <irogers@google.com>
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On Wed, Dec 2, 2020 at 11:28 AM Andi Kleen <ak@linux.intel.com> wrote:
>
> > +     prev_cgrp = task_css_check(prev, perf_event_cgrp_id, 1)->cgroup;
> > +     next_cgrp = task_css_check(next, perf_event_cgrp_id, 1)->cgroup;
> > +
> > +     if (prev_cgrp != next_cgrp)
> > +             perf_sw_event_sched(PERF_COUNT_SW_CGROUP_SWITCHES, 1, 0);
>
> Seems to be the perf cgroup only, not all cgroups.
> That's a big difference and needs to be documented properly.
>
We care about the all-cgroup case.

> Probably would make sense to have two events for both, one for
> all cgroups and one for perf only.
>
>
>
> -Andi