linux-kernel - Re: [PATCH v1 05/10] perf evsel: Limit in group test to CPUs

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Date:   Thu, 2 Mar 2023 11:38:23 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Steinar H. Gunderson" <sesse@...gle.com>,
        Qi Liu <liuqi115@...wei.com>,
        Kim Phillips <kim.phillips@....com>,
        Florian Fischer <florian.fischer@...q.space>,
        James Clark <james.clark@....com>,
        Suzuki Poulouse <suzuki.poulose@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.g.garry@...cle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v1 05/10] perf evsel: Limit in group test to CPUs

On Thu, Mar 2, 2023 at 7:24 AM Liang, Kan <kan.liang@...ux.intel.com> wrote:
>
>
>
> On 2023-03-01 11:12 p.m., Ian Rogers wrote:
> > Don't just match on the event name, restict based on the PMU too.
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> >  tools/perf/arch/x86/util/evsel.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/tools/perf/arch/x86/util/evsel.c b/tools/perf/arch/x86/util/evsel.c
> > index ea3972d785d1..580b0a172136 100644
> > --- a/tools/perf/arch/x86/util/evsel.c
> > +++ b/tools/perf/arch/x86/util/evsel.c
> > @@ -61,6 +61,9 @@ bool arch_evsel__must_be_in_group(const struct evsel *evsel)
> >       if (!evsel__sys_has_perf_metrics(evsel))
> >               return false;
> >
> > +     if (evsel->pmu_name && strncmp(evsel->pmu_name, "cpu", 3))
> > +             return false;
>
> I'm not sure why we want to check the pmu name. It seems better to move
> it into evsel__sys_has_perf_metrics(), since perf_metrics is a core PMU
> only feature.
>
> I think the strncmp(evsel->pmu_name, "cpu", 3) is to check whether it is
> a core PMU. It is also used in other places. I think it's better to
> factor out it, e.g., arch_evsel__is_core_pmu(). It will deliver a clear
> message of what we are doing here.
>
> Thanks,
> Kan

I missed the behavior of evsel__sys_has_perf_metrics and think we can
just drop this change. We should probably rename
evsel__sys_has_perf_metrics perhaps something like
arch_evsel__pmu_has_topdown_events.

Thanks,
Ian

> > +
> >       return evsel->name &&
> >               (strcasestr(evsel->name, "slots") ||
> >                strcasestr(evsel->name, "topdown"));