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/ui/gtk/hists.c b/tools/perf/ui/gtk/hists.c
index 9c02c4c..1e764a8 100644
--- a/tools/perf/ui/gtk/hists.c
+++ b/tools/perf/ui/gtk/hists.c
@@ -270,10 +270,18 @@
 		const char *evname = perf_evsel__name(pos);
 		GtkWidget *scrolled_window;
 		GtkWidget *tab_label;
+		char buf[512];
+		size_t size = sizeof(buf);
 
-		if (symbol_conf.event_group &&
-		    !perf_evsel__is_group_leader(pos))
-			continue;
+		if (symbol_conf.event_group) {
+			if (!perf_evsel__is_group_leader(pos))
+				continue;
+
+			if (pos->nr_members > 1) {
+				perf_evsel__group_desc(pos, buf, size);
+				evname = buf;
+			}
+		}
 
 		scrolled_window = gtk_scrolled_window_new(NULL, NULL);