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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
Date: Wed, 25 Mar 2026 00:04:27 -0700	[thread overview]
Message-ID: <acOI-3Rtjys7JPyl@google.com> (raw)
In-Reply-To: <CAP-5=fXwDgZ-+JT2c8y3sJLURGAz1njduLZRxTJ548xbW+H9Jg@mail.gmail.com>

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

  reply	other threads:[~2026-03-25  7:04 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-19  6:45 [PATCH v3] perf test: Fix perf stat --bpf-counters on hybrid machines Namhyung Kim
2026-03-22 22:05 ` Arnaldo Carvalho de Melo
2026-03-23 20:15   ` Ian Rogers
2026-03-23 20:24     ` [RFC PATCH v1] " Ian Rogers
2026-03-23 20:26       ` Ian Rogers
2026-03-25  7:04         ` Namhyung Kim [this message]
2026-03-25 17:16           ` [PATCH v2] " Ian Rogers
2026-04-03 19:20             ` Falcon, Thomas
2026-04-01 21:52 ` [PATCH v3] " Namhyung Kim

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