linux-kernel - Re: [PATCH v1 03/10] perf record: Early auxtrace initialization before event parsing

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Date:   Thu, 2 Mar 2023 08:05:53 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...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>,
        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 03/10] perf record: Early auxtrace initialization
 before event parsing

On Thu, Mar 2, 2023 at 6:32 AM Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
>
> Em Wed, Mar 01, 2023 at 08:12:04PM -0800, Ian Rogers escreveu:
> > This allows event parsing to use the evsel__is_aux_event function,
> > which is important when determining event grouping.
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> >  tools/perf/arch/x86/util/auxtrace.c | 17 +++++++++++++----
> >  tools/perf/builtin-record.c         |  6 ++++++
> >  tools/perf/util/auxtrace.h          |  2 ++
> >  3 files changed, 21 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/arch/x86/util/auxtrace.c b/tools/perf/arch/x86/util/auxtrace.c
> > index 3da506e13f49..de1e4842ea2e 100644
> > --- a/tools/perf/arch/x86/util/auxtrace.c
> > +++ b/tools/perf/arch/x86/util/auxtrace.c
> > @@ -15,6 +15,19 @@
> >  #include "../../../util/intel-bts.h"
> >  #include "../../../util/evlist.h"
> >
> > +void auxtrace__early_init(void)
> > +{
> > +     struct perf_pmu *intel_pt_pmu;
> > +     struct perf_pmu *intel_bts_pmu;
> > +
> > +     intel_pt_pmu = perf_pmu__find(INTEL_PT_PMU_NAME);
> > +     if (intel_pt_pmu)
> > +             intel_pt_pmu->auxtrace = true;
> > +     intel_bts_pmu = perf_pmu__find(INTEL_BTS_PMU_NAME);
> > +     if (intel_bts_pmu)
> > +             intel_bts_pmu->auxtrace = true;
> > +}
> > +
> >  static
> >  struct auxtrace_record *auxtrace_record__init_intel(struct evlist *evlist,
> >                                                   int *err)
> > @@ -26,11 +39,7 @@ struct auxtrace_record *auxtrace_record__init_intel(struct evlist *evlist,
> >       bool found_bts = false;
> >
> >       intel_pt_pmu = perf_pmu__find(INTEL_PT_PMU_NAME);
> > -     if (intel_pt_pmu)
> > -             intel_pt_pmu->auxtrace = true;
>
> In this case, can't we do it as:
>
>         if (intel_pt_pmu == NULL && intel_bts_pmu == NULL)
>                 auxtrace__early_init();
>
> To avoid possibly doing the finds again?
>
> - Arnaldo

So this code is called after parse events and has the evlist. The
early init code is called before parse events so that the aux trace
PMUs are flagged for the sake of the is_aux call in evsel__pmu_name,
as aux events must be grouped with their different PMU type leader. It
won't be possible to combine the calls but I plan to look at
restructuring how PMUs are accessed so that searches are less
necessary.

Thanks,
Ian

> >       intel_bts_pmu = perf_pmu__find(INTEL_BTS_PMU_NAME);
> > -     if (intel_bts_pmu)
> > -             intel_bts_pmu->auxtrace = true;
> >
> >       evlist__for_each_entry(evlist, evsel) {
> >               if (intel_pt_pmu && evsel->core.attr.type == intel_pt_pmu->type)
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index 8374117e66f6..a0870c076dc0 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -3940,6 +3940,10 @@ static int record__init_thread_masks(struct record *rec)
> >       return ret;
> >  }
> >
> > +__weak void auxtrace__early_init(void)
> > +{
> > +}
> > +
> >  int cmd_record(int argc, const char **argv)
> >  {
> >       int err;
> > @@ -3985,6 +3989,8 @@ int cmd_record(int argc, const char **argv)
> >       if (err)
> >               return err;
> >
> > +     auxtrace__early_init();
> > +
> >       argc = parse_options(argc, argv, record_options, record_usage,
> >                           PARSE_OPT_STOP_AT_NON_OPTION);
> >       if (quiet)
> > diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> > index 29eb82dff574..49a86aa6ac94 100644
> > --- a/tools/perf/util/auxtrace.h
> > +++ b/tools/perf/util/auxtrace.h
> > @@ -457,6 +457,8 @@ struct addr_filters {
> >
> >  struct auxtrace_cache;
> >
> > +void auxtrace__early_init(void);
> > +
> >  #ifdef HAVE_AUXTRACE_SUPPORT
> >
> >  u64 compat_auxtrace_mmap__read_head(struct auxtrace_mmap *mm);
> > --
> > 2.39.2.722.g9855ee24e9-goog
> >
>
> --
>
> - Arnaldo