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Date: Wed, 25 Mar 2026 00:04:27 -0700
From: Namhyung Kim <namhyung@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: acme@kernel.org, adrian.hunter@intel.com, james.clark@linaro.org,
	jolsa@kernel.org, linux-kernel@vger.kernel.org,
	linux-perf-users@vger.kernel.org, mingo@kernel.org,
	peterz@infradead.org
Subject: Re: [RFC PATCH v1] perf test: Fix perf stat --bpf-counters on hybrid
 machines
Message-ID: <acOI-3Rtjys7JPyl@google.com>
References: <CAP-5=fW5Cx-a0hm_PKNLDSmo=L0xu=LizKiAPyJF1YtH-coFdg@mail.gmail.com>
 <20260323202409.194123-1-irogers@google.com>
 <CAP-5=fXwDgZ-+JT2c8y3sJLURGAz1njduLZRxTJ548xbW+H9Jg@mail.gmail.com>
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On Mon, Mar 23, 2026 at 01:26:11PM -0700, Ian Rogers wrote:
> On Mon, Mar 23, 2026 at 1:24 PM Ian Rogers <irogers@google.com> wrote:
> >
> > Events on hardware PMUs may open on >1 hardware PMU on hybrid
> > machines. Unfortunately multiplexing introduces a scaling issue as
> > reported in:
> > https://lore.kernel.org/lkml/20250716223924.825772-1-irogers@google.com/
> >
> > Switch to using task-clock which as a software event runs on all CPUs
> > and has a single PMU.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> 
> With hindsight, maybe the better thing to do is Namhyung's patch plus
> the "--no-scale" option to `perf stat` to sidestep the scaling issue.
> It'd be great to make this test not "(exclusive)", it shouldn't be
> necessary. You can test for flakiness with the '-r' option to `perf
> test` which takes a repeat count.

I think your fix is simpler and better. :)

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung