linux-kernel - Re: [PATCH 02/19] perf tools: Use pmu info in evsel__is

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Date:   Mon, 10 Oct 2022 15:31:41 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Leo Yan <leo.yan@...aro.org>, Andi Kleen <ak@...ux.intel.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        James Clark <james.clark@....com>,
        Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Subject: Re: [PATCH 02/19] perf tools: Use pmu info in evsel__is_hybrid()

On Sun, Oct 9, 2022 at 10:36 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> If evsel has pmu, it can use pmu->is_hybrid directly.
>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/evsel.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 196f8e4859d7..a6ea91c72659 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -3132,6 +3132,9 @@ void evsel__zero_per_pkg(struct evsel *evsel)
>
>  bool evsel__is_hybrid(struct evsel *evsel)
>  {
> +       if (evsel->pmu)
> +               return evsel->pmu->is_hybrid;
> +
>         return evsel->pmu_name && perf_pmu__is_hybrid(evsel->pmu_name);

Wow, there's so much duplicated state. Why do evsels have a pmu_name
and a pmu? Why not just pmu->name? I feel always having a pmu would be
cleanest here. That said what does evsel__is_hybrid even mean? Does it
mean this event is on a PMU normally called cpu and called cpu_core
and cpu_atom on hybrid systems? And of course there are no comments to
explain what this little mystery could be. Anyway, that's not a fault
of this change, and probably later changes will go someway toward
cleaning this up. It was a shame the code wasn't cleaner in the first
place.

Acked-by: Ian Rogers

Thanks,
Ian

>  }
>
> --
> 2.38.0.rc1.362.ged0d419d3c-goog
>