perf stat record: Write stat round events on record

Writing stat round events on 'perf stat record' for each interval round.
In non interval mode we store round event after the last stat event.

Committer note:

After the patch:

  $ perf report -D | grep PERF_RECORD | grep ROUND
  0x852 [0x18]: PERF_RECORD_STAT_ROUND
  $

Reported-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1446734469-11352-9-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-stat.c

@@ -231,6 +231,16 @@ static int process_synthesized_event(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
+static int write_stat_round_event(u64 time, u64 type)
+{
+	return perf_event__synthesize_stat_round(NULL, time, type,
+						 process_synthesized_event,
+						 NULL);
+}
+
+#define WRITE_STAT_ROUND_EVENT(time, interval) \
+	write_stat_round_event(time, PERF_STAT_ROUND_TYPE__ ## interval)
+
 #define SID(e, x, y) xyarray__entry(e->sample_id, x, y)
 
 static int
@@ -306,6 +316,11 @@ static void process_interval(void)
 	clock_gettime(CLOCK_MONOTONIC, &ts);
 	diff_timespec(&rs, &ts, &ref_time);
 
+	if (STAT_RECORD) {
+		if (WRITE_STAT_ROUND_EVENT(rs.tv_sec * NSECS_PER_SEC + rs.tv_nsec, INTERVAL))
+			pr_err("failed to write stat round event\n");
+	}
+
 	print_counters(&rs, 0, NULL);
 }
 
@@ -1670,6 +1685,11 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
 				   "older tools may produce warnings about this file\n.");
 		}
 
+		if (!interval) {
+			if (WRITE_STAT_ROUND_EVENT(walltime_nsecs_stats.max, FINAL))
+				pr_err("failed to write stat round event\n");
+		}
+
 		if (!perf_stat.file.is_pipe) {
 			perf_stat.session->header.data_size += perf_stat.bytes_written;
 			perf_session__write_header(perf_stat.session, evsel_list, fd, true);