perf report: Make another loop for linking group hists

Now the event grouping viewing requires linking all member hists in a
group to the leader's.  Thus hists__output_resort should be called after
linking all events in evlist.

Introduce symbol_conf.event_group flag to determine whether the feature
is enabled or not.

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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1358845787-1350-5-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -416,8 +416,16 @@ static int __cmd_report(struct perf_report *rep)
 			hists->symbol_filter_str = rep->symbol_filter_str;
 
 		hists__collapse_resort(hists);
-		hists__output_resort(hists);
 		nr_samples += hists->stats.nr_events[PERF_RECORD_SAMPLE];
+
+		/* Non-group events are considered as leader */
+		if (symbol_conf.event_group &&
+		    !perf_evsel__is_group_leader(pos)) {
+			struct hists *leader_hists = &pos->leader->hists;
+
+			hists__match(leader_hists, hists);
+			hists__link(leader_hists, hists);
+		}
 	}
 
 	if (nr_samples == 0) {
@@ -425,6 +433,9 @@ static int __cmd_report(struct perf_report *rep)
 		goto out_delete;
 	}
 
+	list_for_each_entry(pos, &session->evlist->entries, node)
+		hists__output_resort(&pos->hists);
+
 	if (use_browser > 0) {
 		if (use_browser == 1) {
 			perf_evlist__tui_browse_hists(session->evlist, help,

tools/perf/util/symbol.h

@@ -96,7 +96,8 @@ struct symbol_conf {
 			initialized,
 			kptr_restrict,
 			annotate_asm_raw,
-			annotate_src;
+			annotate_src,
+			event_group;
 	const char	*vmlinux_name,
 			*kallsyms_name,
 			*source_prefix,