4 files changed, 67 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index 15e8b48077ba..f7d85e89a98a 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -261,6 +261,10 @@ struct {
 	struct perf_header_string map;
 }[number_of_cache_levels];
 
+	HEADER_SAMPLE_TIME = 21,
+
+Two uint64_t for the time of first sample and the time of last sample.
+
 	other bits are reserved and should ignored for now
 	HEADER_FEAT_BITS	= 256,
 
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 75160666d305..e7fbca69cbac 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -50,6 +50,8 @@ struct perf_evlist {
 	struct perf_evsel *selected;
 	struct events_stats stats;
 	struct perf_env	*env;
+	u64		first_sample_time;
+	u64		last_sample_time;
 };
 
 struct perf_evsel_str_handler {
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index ca73aa7be708..a326e0d8b5b6 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -16,6 +16,7 @@
 #include <linux/stringify.h>
 #include <sys/stat.h>
 #include <sys/utsname.h>
+#include <linux/time64.h>
 
 #include "evlist.h"
 #include "evsel.h"
@@ -35,6 +36,7 @@
 #include <api/fs/fs.h>
 #include "asm/bug.h"
 #include "tool.h"
+#include "time-utils.h"
 
 #include "sane_ctype.h"
 
@@ -1180,6 +1182,20 @@ static int write_stat(struct feat_fd *ff __maybe_unused,
 	return 0;
 }
 
+static int write_sample_time(struct feat_fd *ff,
+			     struct perf_evlist *evlist)
+{
+	int ret;
+
+	ret = do_write(ff, &evlist->first_sample_time,
+		       sizeof(evlist->first_sample_time));
+	if (ret < 0)
+		return ret;
+
+	return do_write(ff, &evlist->last_sample_time,
+			sizeof(evlist->last_sample_time));
+}
+
 static void print_hostname(struct feat_fd *ff, FILE *fp)
 {
 	fprintf(fp, "# hostname : %s\n", ff->ph->env.hostname);
@@ -1505,6 +1521,28 @@ static void print_group_desc(struct feat_fd *ff, FILE *fp)
 	}
 }
 
+static void print_sample_time(struct feat_fd *ff, FILE *fp)
+{
+	struct perf_session *session;
+	char time_buf[32];
+	double d;
+
+	session = container_of(ff->ph, struct perf_session, header);
+
+	timestamp__scnprintf_usec(session->evlist->first_sample_time,
+				  time_buf, sizeof(time_buf));
+	fprintf(fp, "# time of first sample : %s\n", time_buf);
+
+	timestamp__scnprintf_usec(session->evlist->last_sample_time,
+				  time_buf, sizeof(time_buf));
+	fprintf(fp, "# time of last sample : %s\n", time_buf);
+
+	d = (double)(session->evlist->last_sample_time -
+		session->evlist->first_sample_time) / NSEC_PER_MSEC;
+
+	fprintf(fp, "# sample duration : %10.3f ms\n", d);
+}
+
 static int __event_process_build_id(struct build_id_event *bev,
 				    char *filename,
 				    struct perf_session *session)
@@ -2146,6 +2184,27 @@ out_free_caches:
 	return -1;
 }
 
+static int process_sample_time(struct feat_fd *ff, void *data __maybe_unused)
+{
+	struct perf_session *session;
+	u64 first_sample_time, last_sample_time;
+	int ret;
+
+	session = container_of(ff->ph, struct perf_session, header);
+
+	ret = do_read_u64(ff, &first_sample_time);
+	if (ret)
+		return -1;
+
+	ret = do_read_u64(ff, &last_sample_time);
+	if (ret)
+		return -1;
+
+	session->evlist->first_sample_time = first_sample_time;
+	session->evlist->last_sample_time = last_sample_time;
+	return 0;
+}
+
 struct feature_ops {
 	int (*write)(struct feat_fd *ff, struct perf_evlist *evlist);
 	void (*print)(struct feat_fd *ff, FILE *fp);
@@ -2203,6 +2262,7 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
 	FEAT_OPN(AUXTRACE,	auxtrace,	false),
 	FEAT_OPN(STAT,		stat,		false),
 	FEAT_OPN(CACHE,		cache,		true),
+	FEAT_OPR(SAMPLE_TIME,	sample_time,	false),
 };
 
 struct header_print_data {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 317fb901e47f..f28aaaa3a440 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -35,6 +35,7 @@ enum {
 	HEADER_AUXTRACE,
 	HEADER_STAT,
 	HEADER_CACHE,
+	HEADER_SAMPLE_TIME,
 	HEADER_LAST_FEATURE,
 	HEADER_FEAT_BITS	= 256,
 };