Subject: Re: [PATCH v4] perf metricgroup: Fix uncore metric expressions

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Wed, 23 Sep 2020 17:25:08 -0300

Em Wed, Sep 23, 2020 at 12:59:28PM -0700, Ian Rogers escreveu:
> On Thu, Sep 17, 2020 at 6:47 PM Namhyung Kim <[email-masked]> wrote:
> >
> > Hi Arnaldo,
> >
> > On Fri, Sep 18, 2020 at 5:39 AM Arnaldo Carvalho de Melo
> > <[email-masked]> wrote:
> > >
> > > Em Thu, Sep 17, 2020 at 01:18:07PM -0700, Ian Rogers escreveu:
> > > > A metric like DRAM_BW_Use has on SkylakeX events uncore_imc/cas_count_read/
> > > > and uncore_imc/case_count_write/. These events open 6 events per socket
> > > > with pmu names of uncore_imc_[0-5]. The current metric setup code in
> > > > find_evsel_group assumes one ID will map to 1 event to be recorded in
> > > > metric_events. For events with multiple matches, the first event is
> > > > recorded in metric_events (avoiding matching >1 event with the same
> > > > name) and the evlist_used updated so that duplicate events aren't
> > > > removed when the evlist has unused events removed.
> > >
> > > Namhyung, please check if you still Acks this as you provided it for v3.
> >
> > Sure,
> >
> > Acked-by: Namhyung Kim <[email-masked]>
> 
> Thanks Namhyung and Arnaldo, could we merge this?

[acme@five perf]$ git log --oneline perf/urgent
dcc81be0fc4e6694 (quaco/perf/urgent, perf/urgent) perf metricgroup: Fix uncore metric expressions
0f1b550e29c1f952 perf parse-event: Release cpu_map refcount if evsel alloc failed
5d680be3b014d583 perf parse-event: Fix cpu map refcounting
5925fa68fe824465 (torvalds/master) Merge tag 'perf-tools-fixes-for-v5.9-2020-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

I have it already locally, need to finish a round of testing so that I
can push it publicly,

- Arnaldo
 
> Ian
> 
> > Thanks
> > Namhyung
> >
> > >
> > > > Before this change:
> > > > $ /tmp/perf/perf stat -M DRAM_BW_Use -a -- sleep 1
> > > >
> > > >  Performance counter stats for 'system wide':
> > > >
> > > >              41.14 MiB  uncore_imc/cas_count_read/
> > > >      1,002,614,251 ns   duration_time
> > > >
> > > >        1.002614251 seconds time elapsed
> > > >
> > > > After this change:
> > > > $ /tmp/perf/perf stat -M DRAM_BW_Use -a -- sleep 1
> > > >
> > > >  Performance counter stats for 'system wide':
> > > >
> > > >             157.47 MiB  uncore_imc/cas_count_read/ #     0.00 DRAM_BW_Use
> > > >             126.97 MiB  uncore_imc/cas_count_write/
> > > >      1,003,019,728 ns   duration_time
> > > >
> > > > Erroneous duplication introduced in:
> > > > commit 2440689d62e9 ("perf metricgroup: Remove duped metric group events").
> > > >
> > > > Fixes: ded80bda8bc9 ("perf expr: Migrate expr ids table to a hashmap").
> > > > Reported-by: Jin Yao <[email-masked]>
> > > > Signed-off-by: Ian Rogers <[email-masked]>
> > > > ---
> > > >  tools/perf/util/metricgroup.c | 75 ++++++++++++++++++++++++++---------
> > > >  1 file changed, 56 insertions(+), 19 deletions(-)
> > > >
> > > > diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> > > > index ab5030fcfed4..d948a7f910cf 100644
> > > > --- a/tools/perf/util/metricgroup.c
> > > > +++ b/tools/perf/util/metricgroup.c
> > > > @@ -150,6 +150,18 @@ static void expr_ids__exit(struct expr_ids *ids)
> > > >               free(ids->id[i].id);
> > > >  }
> > > >
> > > > +static bool contains_event(struct evsel **metric_events, int num_events,
> > > > +                     const char *event_name)
> > > > +{
> > > > +     int i;
> > > > +
> > > > +     for (i = 0; i < num_events; i++) {
> > > > +             if (!strcmp(metric_events[i]->name, event_name))
> > > > +                     return true;
> > > > +     }
> > > > +     return false;
> > > > +}
> > > > +
> > > >  /**
> > > >   * Find a group of events in perf_evlist that correpond to those from a parsed
> > > >   * metric expression. Note, as find_evsel_group is called in the same order as
> > > > @@ -180,7 +192,11 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist,
> > > >       int i = 0, matched_events = 0, events_to_match;
> > > >       const int idnum = (int)hashmap__size(&pctx->ids);
> > > >
> > > > -     /* duration_time is grouped separately. */
> > > > +     /*
> > > > +      * duration_time is always grouped separately, when events are grouped
> > > > +      * (ie has_constraint is false) then ignore it in the matching loop and
> > > > +      * add it to metric_events at the end.
> > > > +      */
> > > >       if (!has_constraint &&
> > > >           hashmap__find(&pctx->ids, "duration_time", (void **)&val_ptr))
> > > >               events_to_match = idnum - 1;
> > > > @@ -207,23 +223,20 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist,
> > > >                               sizeof(struct evsel *) * idnum);
> > > >                       current_leader = ev->leader;
> > > >               }
> > > > -             if (hashmap__find(&pctx->ids, ev->name, (void **)&val_ptr)) {
> > > > -                     if (has_constraint) {
> > > > -                             /*
> > > > -                              * Events aren't grouped, ensure the same event
> > > > -                              * isn't matched from two groups.
> > > > -                              */
> > > > -                             for (i = 0; i < matched_events; i++) {
> > > > -                                     if (!strcmp(ev->name,
> > > > -                                                 metric_events[i]->name)) {
> > > > -                                             break;
> > > > -                                     }
> > > > -                             }
> > > > -                             if (i != matched_events)
> > > > -                                     continue;
> > > > -                     }
> > > > +             /*
> > > > +              * Check for duplicate events with the same name. For example,
> > > > +              * uncore_imc/cas_count_read/ will turn into 6 events per socket
> > > > +              * on skylakex. Only the first such event is placed in
> > > > +              * metric_events. If events aren't grouped then this also
> > > > +              * ensures that the same event in different sibling groups
> > > > +              * aren't both added to metric_events.
> > > > +              */
> > > > +             if (contains_event(metric_events, matched_events, ev->name))
> > > > +                     continue;
> > > > +             /* Does this event belong to the parse context? */
> > > > +             if (hashmap__find(&pctx->ids, ev->name, (void **)&val_ptr))
> > > >                       metric_events[matched_events++] = ev;
> > > > -             }
> > > > +
> > > >               if (matched_events == events_to_match)
> > > >                       break;
> > > >       }
> > > > @@ -239,7 +252,7 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist,
> > > >       }
> > > >
> > > >       if (matched_events != idnum) {
> > > > -             /* Not whole match */
> > > > +             /* Not a whole match */
> > > >               return NULL;
> > > >       }
> > > >
> > > > @@ -247,8 +260,32 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist,
> > > >
> > > >       for (i = 0; i < idnum; i++) {
> > > >               ev = metric_events[i];
> > > > -             ev->metric_leader = ev;
> > > > +             /* Don't free the used events. */
> > > >               set_bit(ev->idx, evlist_used);
> > > > +             /*
> > > > +              * The metric leader points to the identically named event in
> > > > +              * metric_events.
> > > > +              */
> > > > +             ev->metric_leader = ev;
> > > > +             /*
> > > > +              * Mark two events with identical names in the same group (or
> > > > +              * globally) as being in use as uncore events may be duplicated
> > > > +              * for each pmu. Set the metric leader of such events to be the
> > > > +              * event that appears in metric_events.
> > > > +              */
> > > > +             evlist__for_each_entry_continue(perf_evlist, ev) {
> > > > +                     /*
> > > > +                      * If events are grouped then the search can terminate
> > > > +                      * when then group is left.
> > > > +                      */
> > > > +                     if (!has_constraint &&
> > > > +                         ev->leader != metric_events[i]->leader)
> > > > +                             break;
> > > > +                     if (!strcmp(metric_events[i]->name, ev->name)) {
> > > > +                             set_bit(ev->idx, evlist_used);
> > > > +                             ev->metric_leader = metric_events[i];
> > > > +                     }
> > > > +             }
> > > >       }
> > > >
> > > >       return metric_events[0];
> > > > --
> > > > 2.28.0.618.gf4bc123cb7-goog
> > > >
> > >
> > > --
> > >
> > > - Arnaldo

-- 

- Arnaldo