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From:   Stephane Eranian <eranian@google.com>
Date:   Wed, 2 Dec 2020 15:40:42 -0800
Message-ID: <CABPqkBRsS2+gT-792uYq+U84LJepDjY=wwiLku6mtVhgd8mEEA@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 2:42 PM Andi Kleen <ak@linux.intel.com> wrote:
>
> On Wed, Dec 02, 2020 at 11:47:25AM -0800, Stephane Eranian wrote:
> > 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.
>
> Then it's not correct I think. You need a different hook point.
>
I realize that ;-(