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

[Ian Rogers]

On Mon, Jun 22, 2026 at 11:22 PM Qinxin Xia <xiaqinxin@xxxxxxxxxx> wrote:
>
>
>
> On 2026/6/23 01:53:52, Ian Rogers <irogers@xxxxxxxxxx> wrote:
> > 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.
> >
> Perhaps we can do it this way：
>         if (pmu->is_core && !strcmp(wildcard_to_match, "default_core"))
>                 return true;
>
>         bool need_fnmatch = strisglob(wildcard_to_match);

Unfortunately we require variables to be declared at the top of
blocks/functions.

> > Would it be okay to supply a Reviewed-by tag? I notice this fix is
> > missing from perf-tools-next.
> >
> Sure, add my Reviewed‑by.:-)

Thanks,
Ian

>
> > Thanks!
> > Ian
> >
> >> --
> >> Thanks,
> >> Qinxin
>
> --
> Thanks,
> Qinxin
>