perf metricgroup: Support multiple events for metricgroup

Some uncore metrics don't work as expected. For example, on
cascadelakex:

  root@lkp-csl-2sp2:~# perf stat -M UNC_M_PMM_BANDWIDTH.TOTAL -a -- sleep 1

   Performance counter stats for 'system wide':

           1841092      unc_m_pmm_rpq_inserts
           3680816      unc_m_pmm_wpq_inserts

       1.001775055 seconds time elapsed

  root@lkp-csl-2sp2:~# perf stat -M UNC_M_PMM_READ_LATENCY -a -- sleep 1

   Performance counter stats for 'system wide':

         860649746      unc_m_pmm_rpq_occupancy.all
           1840557      unc_m_pmm_rpq_inserts
       12790627455      unc_m_clockticks

       1.001773348 seconds time elapsed

No metrics 'UNC_M_PMM_BANDWIDTH.TOTAL' or 'UNC_M_PMM_READ_LATENCY' are
reported.

The issue is, the case of an alias expanding to mulitple events is not
supported, typically the uncore events.  (see comments in
find_evsel_group()).

For UNC_M_PMM_BANDWIDTH.TOTAL in above example, the expanded event group
is '{unc_m_pmm_rpq_inserts,unc_m_pmm_wpq_inserts}:W', but the actual
events passed to find_evsel_group are:

  unc_m_pmm_rpq_inserts
  unc_m_pmm_rpq_inserts
  unc_m_pmm_rpq_inserts
  unc_m_pmm_rpq_inserts
  unc_m_pmm_rpq_inserts
  unc_m_pmm_rpq_inserts
  unc_m_pmm_wpq_inserts
  unc_m_pmm_wpq_inserts
  unc_m_pmm_wpq_inserts
  unc_m_pmm_wpq_inserts
  unc_m_pmm_wpq_inserts
  unc_m_pmm_wpq_inserts

For this multiple events case, it's not supported well.

This patch introduces a new field 'metric_leader' in struct evsel. The
first event is considered as a metric leader. For the rest of same
events, they point to the first event via it's metric_leader field in
struct evsel.

This design is for adding the counting results of all same events to the
first event in group (the metric_leader).

With this patch,

  root@lkp-csl-2sp2:~# perf stat -M UNC_M_PMM_BANDWIDTH.TOTAL -a -- sleep 1

   Performance counter stats for 'system wide':

           1842108      unc_m_pmm_rpq_inserts     #    337.2 MB/sec  UNC_M_PMM_BANDWIDTH.TOTAL
           3682209      unc_m_pmm_wpq_inserts

       1.001819706 seconds time elapsed

  root@lkp-csl-2sp2:~# perf stat -M UNC_M_PMM_READ_LATENCY -a -- sleep 1

   Performance counter stats for 'system wide':

         861970685      unc_m_pmm_rpq_occupancy.all #    219.4 ns  UNC_M_PMM_READ_LATENCY
           1842772      unc_m_pmm_rpq_inserts
       12790196356      unc_m_clockticks

       1.001749103 seconds time elapsed

Now we can see the correct metrics 'UNC_M_PMM_BANDWIDTH.TOTAL' and
'UNC_M_PMM_READ_LATENCY'.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20190828055932.8269-5-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 44 insertions, 40 deletions

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index f474a29f1b69..a7c0424dbda3 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -90,57 +90,61 @@ struct egroup {
 	const char *metric_unit;
 };
 
-static bool record_evsel(int *ind, struct evsel **start,
-			 int idnum,
-			 struct evsel **metric_events,
-			 struct evsel *ev)
-{
-	metric_events[*ind] = ev;
-	if (*ind == 0)
-		*start = ev;
-	if (++*ind == idnum) {
-		metric_events[*ind] = NULL;
-		return true;
-	}
-	return false;
-}
-
 static struct evsel *find_evsel_group(struct evlist *perf_evlist,
 				      const char **ids,
 				      int idnum,
 				      struct evsel **metric_events)
 {
-	struct evsel *ev, *start = NULL;
-	int ind = 0;
+	struct evsel *ev;
+	int i = 0;
+	bool leader_found;
 
 	evlist__for_each_entry (perf_evlist, ev) {
-		if (ev->collect_stat)
-			continue;
-		if (!strcmp(ev->name, ids[ind])) {
-			if (record_evsel(&ind, &start, idnum,
-					 metric_events, ev))
-				return start;
+		if (!strcmp(ev->name, ids[i])) {
+			if (!metric_events[i])
+				metric_events[i] = ev;
 		} else {
-			/*
-			 * We saw some other event that is not
-			 * in our list of events. Discard
-			 * the whole match and start again.
-			 */
-			ind = 0;
-			start = NULL;
-			if (!strcmp(ev->name, ids[ind])) {
-				if (record_evsel(&ind, &start, idnum,
-						 metric_events, ev))
-					return start;
+			if (++i == idnum) {
+				/* Discard the whole match and start again */
+				i = 0;
+				memset(metric_events, 0,
+				       sizeof(struct evsel *) * idnum);
+				continue;
+			}
+
+			if (!strcmp(ev->name, ids[i]))
+				metric_events[i] = ev;
+			else {
+				/* Discard the whole match and start again */
+				i = 0;
+				memset(metric_events, 0,
+				       sizeof(struct evsel *) * idnum);
+				continue;
 			}
 		}
 	}
-	/*
-	 * This can happen when an alias expands to multiple
-	 * events, like for uncore events.
-	 * We don't support this case for now.
-	 */
-	return NULL;
+
+	if (i != idnum - 1) {
+		/* Not whole match */
+		return NULL;
+	}
+
+	metric_events[idnum] = NULL;
+
+	for (i = 0; i < idnum; i++) {
+		leader_found = false;
+		evlist__for_each_entry(perf_evlist, ev) {
+			if (!leader_found && (ev == metric_events[i]))
+				leader_found = true;
+
+			if (leader_found &&
+			    !strcmp(ev->name, metric_events[i]->name)) {
+				ev->metric_leader = metric_events[i];
+			}
+		}
+	}
+
+	return metric_events[0];
 }
 
 static int metricgroup__setup_events(struct list_head *groups,