perf evlist: Add --group option

Add '-g/--group' option for showing event groups.  For simplicity it is
currently not compatible with other options.

  $ perf evlist --group
  {ref-cycles,cycles}

  $ perf evlist
  ref-cycles
  cycles

Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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/1358845787-1350-20-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-evlist.txt

@@ -28,6 +28,10 @@ OPTIONS
 --verbose=::
 	Show all fields.
 
+-g::
+--group::
+	Show event group information.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-list[1],

tools/perf/builtin-evlist.c

@@ -39,6 +39,8 @@ int cmd_evlist(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_BOOLEAN('F', "freq", &details.freq, "Show the sample frequency"),
 	OPT_BOOLEAN('v', "verbose", &details.verbose,
 		    "Show all event attr details"),
+	OPT_BOOLEAN('g', "group", &symbol_conf.event_group,
+		    "Show event group information"),
 	OPT_END()
 	};
 	const char * const evlist_usage[] = {
@@ -50,5 +52,10 @@ int cmd_evlist(int argc, const char **argv, const char *prefix __maybe_unused)
 	if (argc)
 		usage_with_options(evlist_usage, options);
 
+	if (symbol_conf.event_group && (details.verbose || details.freq)) {
+		pr_err("--group option is not compatible with other options\n");
+		usage_with_options(evlist_usage, options);
+	}
+
 	return __cmd_evlist(input_name, &details);
 }

tools/perf/util/evsel.c

@@ -1389,7 +1389,27 @@ int perf_evsel__fprintf(struct perf_evsel *evsel,
 			struct perf_attr_details *details, FILE *fp)
 {
 	bool first = true;
-	int printed = fprintf(fp, "%s", perf_evsel__name(evsel));
+	int printed = 0;
+
+	if (symbol_conf.event_group) {
+		struct perf_evsel *pos;
+
+		if (!perf_evsel__is_group_leader(evsel))
+			return 0;
+
+		if (evsel->nr_members > 1)
+			printed += fprintf(fp, "%s{", evsel->group_name ?: "");
+
+		printed += fprintf(fp, "%s", perf_evsel__name(evsel));
+		for_each_group_member(pos, evsel)
+			printed += fprintf(fp, ",%s", perf_evsel__name(pos));
+
+		if (evsel->nr_members > 1)
+			printed += fprintf(fp, "}");
+		goto out;
+	}
+
+	printed += fprintf(fp, "%s", perf_evsel__name(evsel));
 
 	if (details->verbose || details->freq) {
 		printed += comma_fprintf(fp, &first, " sample_freq=%" PRIu64,
@@ -1430,7 +1450,7 @@ int perf_evsel__fprintf(struct perf_evsel *evsel,
 		if_print(bp_type);
 		if_print(branch_sample_type);
 	}
-
+out:
 	fputc('\n', fp);
 	return ++printed;
 }