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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Fri, 4 Dec 2020 16:27:47 +0900
Message-ID: <CAM9d7ciinoE9YZYEf3Mp=sJutEzpfhu+pgWeWusirn846t7j3w@mail.gmail.com>
Subject: Re: [RFC 1/2] perf core: Add PERF_COUNT_SW_CGROUP_SWITCHES event
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Andi Kleen <ak@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Stephane Eranian <eranian@google.com>,
        Ian Rogers <irogers@google.com>
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On Thu, Dec 3, 2020 at 9:20 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Dec 02, 2020 at 11:28:28AM -0800, Andi Kleen 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.
>
> With cgroup-v2 that's all the same, no?

Right, but unfortunately it seems still cgroup v1 is used widely.

Thanks,
Namhyung