perf report: Show group description when event group is enabled

When using event group viewer, it's better to show the group description
rather than the leader information alone.

If a leader did not contain any member, it's a non-group event.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1358845787-1350-17-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 9cc768e..ce518c4 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -299,6 +299,21 @@
 	char unit;
 	unsigned long nr_samples = self->stats.nr_events[PERF_RECORD_SAMPLE];
 	u64 nr_events = self->stats.total_period;
+	struct perf_evsel *evsel = hists_to_evsel(self);
+	char buf[512];
+	size_t size = sizeof(buf);
+
+	if (symbol_conf.event_group && evsel->nr_members > 1) {
+		struct perf_evsel *pos;
+
+		perf_evsel__group_desc(evsel, buf, size);
+		evname = buf;
+
+		for_each_group_member(pos, evsel) {
+			nr_samples += pos->hists.stats.nr_events[PERF_RECORD_SAMPLE];
+			nr_events += pos->hists.stats.total_period;
+		}
+	}
 
 	nr_samples = convert_unit(nr_samples, &unit);
 	ret = fprintf(fp, "# Samples: %lu%c", nr_samples, unit);