trace2: add absolute elapsed time to start event

Add elapsed process time to "start" event to measure
the performance of early process startup.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 11 insertions, 5 deletions

diff --git a/trace2/tr2_tgt.h b/trace2/tr2_tgt.h
index 297bb8ffbe..7b90469212 100644
--- a/trace2/tr2_tgt.h
+++ b/trace2/tr2_tgt.h
@@ -15,6 +15,7 @@ typedef void(tr2_tgt_term_t)(void);
 typedef void(tr2_tgt_evt_version_fl_t)(const char *file, int line);
 
 typedef void(tr2_tgt_evt_start_fl_t)(const char *file, int line,
+				     uint64_t us_elapsed_absolute,
 				     const char **argv);
 typedef void(tr2_tgt_evt_exit_fl_t)(const char *file, int line,
 				    uint64_t us_elapsed_absolute, int code);
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 107cb5317d..89a4d3ae9a 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -122,13 +122,16 @@ static void fn_version_fl(const char *file, int line)
 	jw_release(&jw);
 }
 
-static void fn_start_fl(const char *file, int line, const char **argv)
+static void fn_start_fl(const char *file, int line,
+			uint64_t us_elapsed_absolute, const char **argv)
 {
 	const char *event_name = "start";
 	struct json_writer jw = JSON_WRITER_INIT;
+	double t_abs = (double)us_elapsed_absolute / 1000000.0;
 
 	jw_object_begin(&jw, 0);
 	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_double(&jw, "t_abs", 6, t_abs);
 	jw_object_inline_begin_array(&jw, "argv");
 	jw_array_argv(&jw, argv);
 	jw_end(&jw);
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index 547183d5b6..57f3e18f5b 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -81,7 +81,8 @@ static void fn_version_fl(const char *file, int line)
 	strbuf_release(&buf_payload);
 }
 
-static void fn_start_fl(const char *file, int line, const char **argv)
+static void fn_start_fl(const char *file, int line,
+			uint64_t us_elapsed_absolute, const char **argv)
 {
 	struct strbuf buf_payload = STRBUF_INIT;
 
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index f0746fcf86..9c3b4d8a0f 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -159,15 +159,16 @@ static void fn_version_fl(const char *file, int line)
 	strbuf_release(&buf_payload);
 }
 
-static void fn_start_fl(const char *file, int line, const char **argv)
+static void fn_start_fl(const char *file, int line,
+			uint64_t us_elapsed_absolute, const char **argv)
 {
 	const char *event_name = "start";
 	struct strbuf buf_payload = STRBUF_INIT;
 
 	sq_quote_argv_pretty(&buf_payload, argv);
 
-	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL, NULL,
-			 &buf_payload);
+	perf_io_write_fl(file, line, event_name, NULL, &us_elapsed_absolute,
+			 NULL, NULL, &buf_payload);
 	strbuf_release(&buf_payload);
 }