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References: <20210615011724.672612-1-namhyung@kernel.org> <YMoVOp4+TIUViBb7@hirez.programming.kicks-ass.net>
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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Wed, 16 Jun 2021 09:33:42 -0700
Message-ID: <CAM9d7cj2UhQsd2vx8_C8C_CEW2QQbzs741jCn7f7g-e0i9OiOg@mail.gmail.com>
Subject: Re: [PATCHSET v2 0/3] perf stat: Enable BPF counters with --for-each-cgroup
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andi Kleen <ak@linux.intel.com>,
        Ian Rogers <irogers@google.com>,
        Stephane Eranian <eranian@google.com>,
        Song Liu <songliubraving@fb.com>
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Hi Peter,

On Wed, Jun 16, 2021 at 8:14 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Mon, Jun 14, 2021 at 06:17:21PM -0700, Namhyung Kim wrote:
> > Current limitations are:
> >  * it doesn't support cgroup hierarchy
>
> That seems unfortunate; there's no bpf helper to iterate cgroup
> hierarchy?

I couldn't find one..

>
> >  * there's no reliable way to trigger running the BPF program
>
> You can't attach to the PERF_COUNT_SW_CGROUP_SWITCHES event?

I did it.  But the BPF test run seems not to work with perf_event.
So it needs to trigger a cgroup switch manually..

Thanks,
Namhyung