perf metricgroup: Fix uncore metric expressions

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.

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 <yao.jin@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200917201807.4090224-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index ab5030f..d948a7f 100644 (file)
--- 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];