Re: [PATCH v2] perf metricgroup: Avoid scanning unnecessary PMUs for identifier match

[Arnaldo Carvalho de Melo]

On Thu, May 14, 2026 at 10:39:08AM -0700, Ian Rogers wrote:
> On Wed, May 6, 2026 at 2:12 AM James Clark <james.clark@xxxxxxxxxx> wrote:
> > On 30/04/2026 5:17 pm, Ian Rogers wrote:
> > > Only uncore PMUs can have an identifier, so add an optimized
> > > perf_pmus__scan routine for that case to avoid all PMU types being
> > > created.
> > >
> > > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > > ---
> > >   tools/perf/util/metricgroup.c | 11 +++--------
> > >   tools/perf/util/pmus.c        | 18 +++++++++++++++++-
> > >   tools/perf/util/pmus.h        |  1 +
> > >   3 files changed, 21 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> > > index 4db9578efd81..5a489e97c413 100644
> > > --- a/tools/perf/util/metricgroup.c
> > > +++ b/tools/perf/util/metricgroup.c
> > > @@ -415,14 +415,9 @@ static int metricgroup__sys_event_iter(const struct pmu_metric *pm,
> > >       if (!pm->metric_expr || !pm->compat)
> > >               return 0;
> > >
> > > -     while ((pmu = perf_pmus__scan(pmu))) {
> > > -
> > > -             if (!pmu->id || !pmu_uncore_identifier_match(pm->compat, pmu->id))
> > > -                     continue;
> > > -
> > > -             return d->fn(pm, table, d->data);
> > > -     }
> > > -     return 0;
> > > +     /* Only process with the iterator if there is a a PMU that matches the ID. */
> > > +     pmu = perf_pmus__scan_for_uncore_id(pmu, pm->compat);
> > > +     return pmu ? d->fn(pm, table, d->data) : 0;
> > >   }
> > >
> > >   int metricgroup__for_each_metric(const struct pmu_metrics_table *table, pmu_metric_iter_fn fn,
> > > diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
> > > index 9a2023ceeefd..5e3f571450fe 100644
> > > --- a/tools/perf/util/pmus.c
> > > +++ b/tools/perf/util/pmus.c
> > > @@ -409,7 +409,7 @@ struct perf_pmu *perf_pmus__scan_matching_wildcard(struct perf_pmu *pmu, const c
> > >       if (!pmu) {
> > >               /*
> > >                * Core PMUs, other sysfs PMUs and tool PMU can have any name or
> > > -              * aren't wother optimizing for.
> > > +              * aren't worth optimizing for.
> > >                */
> > >               unsigned int to_read_pmus =  PERF_TOOL_PMU_TYPE_PE_CORE_MASK |
> > >                       PERF_TOOL_PMU_TYPE_PE_OTHER_MASK |
> > > @@ -486,6 +486,22 @@ static struct perf_pmu *perf_pmus__scan_skip_duplicates(struct perf_pmu *pmu)
> > >       return NULL;
> > >   }
> > >
> > > +struct perf_pmu *perf_pmus__scan_for_uncore_id(struct perf_pmu *pmu, const char *compat)
> > > +{
> > > +     if (!pmu) {
> > > +             /* Only uncore PMUs can have identifiers. */
> > > +             unsigned int to_read_pmus = PERF_TOOL_PMU_TYPE_PE_OTHER_MASK;
> > > +
> > > +             pmu_read_sysfs(to_read_pmus);
> > > +             pmu = list_prepare_entry(pmu, &other_pmus, list);
> > > +     }
> > > +     list_for_each_entry_continue(pmu, &other_pmus, list) {
> > > +             if (pmu->id && pmu_uncore_identifier_match(compat, pmu->id))
> > > +                     return pmu;
> > > +     }
> > > +     return NULL;
> > > +}
> > > +
> > >   const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str)
> > >   {
> > >       struct perf_pmu *pmu = NULL;
> > > diff --git a/tools/perf/util/pmus.h b/tools/perf/util/pmus.h
> > > index 7cb36863711a..0d55edb3f2fc 100644
> > > --- a/tools/perf/util/pmus.h
> > > +++ b/tools/perf/util/pmus.h
> > > @@ -23,6 +23,7 @@ struct perf_pmu *perf_pmus__scan(struct perf_pmu *pmu);
> > >   struct perf_pmu *perf_pmus__scan_core(struct perf_pmu *pmu);
> > >   struct perf_pmu *perf_pmus__scan_for_event(struct perf_pmu *pmu, const char *event);
> > >   struct perf_pmu *perf_pmus__scan_matching_wildcard(struct perf_pmu *pmu, const char *wildcard);
> > > +struct perf_pmu *perf_pmus__scan_for_uncore_id(struct perf_pmu *pmu, const char *compat);
> > >
> > >   const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str);
> > >
> >
> > Reviewed-by: James Clark <james.clark@xxxxxxxxxx>
> 
> Ping.

Thanks, applied to perf-tools-next, for v7.2.

- Arnaldo