linux-kernel - Re: [PATCH v4 4/6] perf cpumap: Handle dummy maps as empty in subset

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Message-ID: <CAP-5=fWwDEW=Vhw1B9i3JN9wr1FJ_+dfaWXjJ7vXeKWfZNaz0g@mail.gmail.com>
Date:   Mon, 2 May 2022 10:04:57 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
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>,
        Namhyung Kim <namhyung@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Kajol Jain <kjain@...ux.ibm.com>,
        James Clark <james.clark@....com>,
        German Gomez <german.gomez@....com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v4 4/6] perf cpumap: Handle dummy maps as empty in subset

On Mon, May 2, 2022 at 9:13 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 30/04/22 09:23, Ian Rogers wrote:
> > perf_cpu_map__empty is true for empty and dummy maps. Make is_subset
> > respect that.
>
> I think this might be the opposite of what I am trying to do, which is
> enable all_cpus to represent all the "cpu" values (3rd parameter of
> perf_event_open()) to iterate over including -1 so that per-thread and
> per-cpu events can be mixed.

Wouldn't you iterate over the cpus of the evsel? I'm not sure using
all_cpus in that way makes sense, it also violates the definition of
empty.

Thanks,
Ian

> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> >  tools/lib/perf/cpumap.c   |  4 ++--
> >  tools/perf/tests/cpumap.c | 10 +++++++++-
> >  2 files changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> > index 384d5e076ee4..9c83675788c2 100644
> > --- a/tools/lib/perf/cpumap.c
> > +++ b/tools/lib/perf/cpumap.c
> > @@ -322,9 +322,9 @@ struct perf_cpu perf_cpu_map__max(struct perf_cpu_map *map)
> >  /** Is 'b' a subset of 'a'. */
> >  bool perf_cpu_map__is_subset(const struct perf_cpu_map *a, const struct perf_cpu_map *b)
> >  {
> > -     if (a == b || !b)
> > +     if (a == b || perf_cpu_map__empty(b))
> >               return true;
> > -     if (!a || b->nr > a->nr)
> > +     if (perf_cpu_map__empty(a) || b->nr > a->nr)
> >               return false;
> >
> >       for (int i = 0, j = 0; i < a->nr; i++) {
> > diff --git a/tools/perf/tests/cpumap.c b/tools/perf/tests/cpumap.c
> > index f94929ebb54b..d52b58395385 100644
> > --- a/tools/perf/tests/cpumap.c
> > +++ b/tools/perf/tests/cpumap.c
> > @@ -128,13 +128,21 @@ static int test__cpu_map_merge(struct test_suite *test __maybe_unused, int subte
> >       struct perf_cpu_map *a = perf_cpu_map__new("4,2,1");
> >       struct perf_cpu_map *b = perf_cpu_map__new("4,5,7");
> >       struct perf_cpu_map *c = perf_cpu_map__merge(a, b);
> > +     struct perf_cpu_map *d = perf_cpu_map__dummy_new();
> > +     struct perf_cpu_map *e = perf_cpu_map__merge(b, d);
> >       char buf[100];
> >
> >       TEST_ASSERT_VAL("failed to merge map: bad nr", perf_cpu_map__nr(c) == 5);
> >       cpu_map__snprint(c, buf, sizeof(buf));
> >       TEST_ASSERT_VAL("failed to merge map: bad result", !strcmp(buf, "1-2,4-5,7"));
> > -     perf_cpu_map__put(b);
> > +
> > +     TEST_ASSERT_VAL("failed to merge map: bad nr", perf_cpu_map__nr(e) == 3);
> > +     cpu_map__snprint(e, buf, sizeof(buf));
> > +     TEST_ASSERT_VAL("failed to merge map: bad result", !strcmp(buf, "4-5,7"));
> > +
> >       perf_cpu_map__put(c);
> > +     perf_cpu_map__put(d);
> > +     perf_cpu_map__put(e);
> >       return 0;
> >  }
> >
>