Re: [PATCH v1] perf pmu: Recognize default_core as a core PMU in more places

[Ian Rogers]

On Mon, Jun 22, 2026 at 2:11 AM Qinxin Xia <xiaqinxin@xxxxxxxxxx> wrote:
>
>
>
> On 2026/6/12 09:24:13, Ian Rogers <irogers@xxxxxxxxxx> wrote:
> > The python metrics code used in places like ilist.py passes a
> > pmu-filter of "default_core" on non-hybrid x86/ARM/.. systems. As a
> > PMU like "cpu" isn't a literal name match then no PMU matches
> > "default_core" and the events fail to parse for the metric. Fix the
> > name matching and PMU lookup for "default_core" and check that it
> > fixes ilist.py.
> >
> > Fixes: 74e2dbe7be50 ("perf tools: Add --pmu-filter option for filtering PMUs")
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > ---
> > Note: this bug is in 7.1 but it is a little too late to send for the
> >        release. It should get picked up via the fixes tag.
> > ---
> >   tools/perf/util/pmu.c  | 6 +++++-
> >   tools/perf/util/pmus.c | 2 ++
> >   2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > index a550f030b85d..836e3b5615cd 100644
> > --- a/tools/perf/util/pmu.c
> > +++ b/tools/perf/util/pmu.c
> > @@ -2660,8 +2660,12 @@ bool perf_pmu__wildcard_match(const struct perf_pmu *pmu, const char *wildcard_t
> >               pmu->name,
> >               pmu->alias_name,
> >       };
> > -     bool need_fnmatch = strisglob(wildcard_to_match);
> > +     bool need_fnmatch;
> >
> > +     if (pmu->is_core && !strcmp(wildcard_to_match, "default_core"))
> > +             return true;
> > +
> > +     need_fnmatch = strisglob(wildcard_to_match);
> >       if (!strncmp(wildcard_to_match, "uncore_", 7))
> >               wildcard_to_match += 7;
> >
> > diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
> > index 5e3f571450fe..e0a4cb2428ca 100644
> > --- a/tools/perf/util/pmus.c
> > +++ b/tools/perf/util/pmus.c
> > @@ -150,6 +150,8 @@ struct perf_pmu *perf_pmus__find(const char *name)
> >       bool core_pmu;
> >       unsigned int to_read_pmus = 0;
> >
> > +     if (!strcmp(name, "default_core"))
> > +             return perf_pmus__find_core_pmu();
> >       /*
> >        * Once PMU is loaded it stays in the list,
> >        * so we keep us from multiple reading/parsing
>
> Thank you for the fix, Ian.
> In the previous patch, I overlooked the handling of the "default_core"
> alias. Also, perhaps we can leave need_fnmatch as-is, since it doesn't
> seem to affect anything here.

Thanks. I moved need_fnmatch's initialization just to save some work
in the "default_core" case where the value is unused. While leaving it
in place would reduce the diff, I think the optimization is worth it
as we would otherwise call strisglob when say iterating all metrics.

Would it be okay to supply a Reviewed-by tag? I notice this fix is
missing from perf-tools-next.

Thanks!
Ian

> --
> Thanks,
> Qinxin
>