linux-kernel - Re: [PATCH v2 06/10] perf evsel: Add function to compute pmu

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Date:   Thu, 2 Mar 2023 17:41:24 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
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>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Steinar H. Gunderson" <sesse@...gle.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 v2 06/10] perf evsel: Add function to compute pmu_name

On Thu, Mar 2, 2023 at 4:19 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Thu, Mar 2, 2023 at 1:26 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > The computed pmu_name respects software events and aux event groups,
> > such that the pmu_name is changed to be that of the aux event leader
> > or group leader for software events. This is done as a later change
> > will split events that are in different PMUs into different groups.
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> >  tools/perf/util/evsel.c | 24 ++++++++++++++++++++++++
> >  tools/perf/util/evsel.h |  1 +
> >  2 files changed, 25 insertions(+)
> >
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index 2dc2c24252bb..9c6b486f8bd4 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -821,6 +821,30 @@ const char *evsel__name(struct evsel *evsel)
> >         return "unknown";
> >  }
> >
> > +const char *evsel__pmu_name(const struct evsel *evsel)
> > +{
> > +       const struct evsel *leader;
> > +
> > +       /* If the pmu_name is set use it. pmu_name isn't set for CPU and software events. */
> > +       if (evsel->pmu_name)
> > +               return evsel->pmu_name;
>
> I'm wondering if we can just use evsel->pmu->name if it's set.

Agreed. I think that can be looked into in follow up work.

> > +       /*
> > +        * Software events may be in a group with other uncore PMU events. Use
> > +        * the pmu_name of the group leader to avoid breaking the software event
> > +        * out of the group.
> > +        *
> > +        * Aux event leaders, like intel_pt, expect a group with events from
> > +        * other PMUs, so substitute the AUX event's PMU in this case.
> > +        */
>
> Looks like we need to rename this function as it doesn't simply return
> the pmu name in the above cases.  Maybe evsel__group_pmu_name() ?

Agreed, that is a better name. I'll add it in v3.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> > +       leader  = evsel__leader(evsel);
> > +       if ((evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) &&
> > +           leader->pmu_name) {
> > +               return leader->pmu_name;
> > +       }
> > +
> > +       return "cpu";
> > +}
> > +
> >  const char *evsel__metric_id(const struct evsel *evsel)
> >  {
> >         if (evsel->metric_id)
> > diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> > index 676c499323e9..72121194d3b1 100644
> > --- a/tools/perf/util/evsel.h
> > +++ b/tools/perf/util/evsel.h
> > @@ -280,6 +280,7 @@ int arch_evsel__hw_name(struct evsel *evsel, char *bf, size_t size);
> >
> >  int __evsel__hw_cache_type_op_res_name(u8 type, u8 op, u8 result, char *bf, size_t size);
> >  const char *evsel__name(struct evsel *evsel);
> > +const char *evsel__pmu_name(const struct evsel *evsel);
> >  const char *evsel__metric_id(const struct evsel *evsel);
> >
> >  static inline bool evsel__is_tool(const struct evsel *evsel)
> > --
> > 2.40.0.rc0.216.gc4246ad0f0-goog
> >