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>
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 32aa2ea..fcece42 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -231,6 +231,16 @@
 	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 @@
 	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 @@
 				   "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);