Re: [PATCH V1 20/23] perf stat: Add requires_cpu flag for uncore

[Ian Rogers <irogers@google.com>]

On Thu, May 5, 2022 at 5:50 PM Ian Rogers <irogers@google.com> wrote:
>
> On Thu, May 5, 2022 at 9:58 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
> >
> > Uncore events require a CPU i.e. it cannot be -1.
> >
> > The evsel system_wide flag is intended for events that should be on every
> > CPU, which does not make sense for uncore events because uncore events do
> > not map one-to-one with CPUs.
> >
> > These 2 requirements are not exactly the same, so introduce a new flag
> > 'requires_cpu' the uncore case.
>
> nit: typo missing 'for' the uncore case.
>
> > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>

Comments coming up in 2 patches time :-)

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> > ---
> >  tools/lib/perf/evlist.c                 | 4 +++-
> >  tools/lib/perf/include/internal/evsel.h | 1 +
> >  tools/perf/builtin-stat.c               | 5 +----
> >  tools/perf/util/evsel.c                 | 1 +
> >  tools/perf/util/parse-events.c          | 2 +-
> >  5 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
> > index 8a82b4b94b99..3bf77f9617b6 100644
> > --- a/tools/lib/perf/evlist.c
> > +++ b/tools/lib/perf/evlist.c
> > @@ -43,7 +43,9 @@ static void __perf_evlist__propagate_maps(struct perf_evlist *evlist,
> >         if (!evsel->own_cpus || evlist->has_user_cpus) {
> >                 perf_cpu_map__put(evsel->cpus);
> >                 evsel->cpus = perf_cpu_map__get(evlist->user_requested_cpus);
> > -       } else if (!evsel->system_wide && perf_cpu_map__empty(evlist->user_requested_cpus)) {
> > +       } else if (!evsel->system_wide &&
> > +                  !evsel->requires_cpu &&
> > +                  perf_cpu_map__empty(evlist->user_requested_cpus)) {
> >                 perf_cpu_map__put(evsel->cpus);
> >                 evsel->cpus = perf_cpu_map__get(evlist->user_requested_cpus);
> >         } else if (evsel->cpus != evsel->own_cpus) {
> > diff --git a/tools/lib/perf/include/internal/evsel.h b/tools/lib/perf/include/internal/evsel.h
> > index cfc9ebd7968e..77fbb8b97e5c 100644
> > --- a/tools/lib/perf/include/internal/evsel.h
> > +++ b/tools/lib/perf/include/internal/evsel.h
> > @@ -50,6 +50,7 @@ struct perf_evsel {
> >         /* parse modifier helper */
> >         int                      nr_members;
>
> From the commit message, could we add the comment:
>
> /* True for events that should be on every CPU. */
>
> However, shouldn't this be captured by the CPU map? Perhaps we can
> have an invariant check that they agree.
>
> >         bool                     system_wide;
>
> /* True for events that cannot be the any CPU (-1), for example,
> uncore events. */
>
> > +       bool                     requires_cpu;
> >         int                      idx;
> >  };
> >
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index 1b96636df01e..c049533f74e4 100644
> > --- a/tools/perf/builtin-stat.c
> > +++ b/tools/perf/builtin-stat.c
> > @@ -385,9 +385,6 @@ static int read_counter_cpu(struct evsel *counter, struct timespec *rs, int cpu_
> >         if (!counter->supported)
> >                 return -ENOENT;
> >
> > -       if (counter->core.system_wide)
> > -               nthreads = 1;
> > -
> >         for (thread = 0; thread < nthreads; thread++) {
> >                 struct perf_counts_values *count;
> >
> > @@ -2264,7 +2261,7 @@ static void setup_system_wide(int forks)
> >                 struct evsel *counter;
> >
> >                 evlist__for_each_entry(evsel_list, counter) {
> > -                       if (!counter->core.system_wide &&
> > +                       if (!counter->core.requires_cpu &&
> >                             strcmp(counter->name, "duration_time")) {
>
> Off-topic of the patch: this test is a tool event check, it'd be better to do:
>
> if (!counter->core.requires_cpu && counter->tool_event != PERF_TOOL_NONE)
>
> Otherwise changes like:
> https://lore.kernel.org/linux-perf-users/20220420102354.468173-1-florian.fischer@muhq.space/
>
> Will break the test. I'll make a note to do a round of clean up.
>
> Thanks,
> Ian
>
>
> >                                 return;
> >                         }
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index d38722560e80..12346293706b 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -382,6 +382,7 @@ struct evsel *evsel__clone(struct evsel *orig)
> >         evsel->core.threads = perf_thread_map__get(orig->core.threads);
> >         evsel->core.nr_members = orig->core.nr_members;
> >         evsel->core.system_wide = orig->core.system_wide;
> > +       evsel->core.requires_cpu = orig->core.requires_cpu;
> >
> >         if (orig->name) {
> >                 evsel->name = strdup(orig->name);
> > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> > index 937f6c9434a2..5227174099b5 100644
> > --- a/tools/perf/util/parse-events.c
> > +++ b/tools/perf/util/parse-events.c
> > @@ -365,7 +365,7 @@ __add_event(struct list_head *list, int *idx,
> >         (*idx)++;
> >         evsel->core.cpus = cpus;
> >         evsel->core.own_cpus = perf_cpu_map__get(cpus);
> > -       evsel->core.system_wide = pmu ? pmu->is_uncore : false;
> > +       evsel->core.requires_cpu = pmu ? pmu->is_uncore : false;
> >         evsel->auto_merge_stats = auto_merge_stats;
> >
> >         if (name)
> > --
> > 2.25.1
> >