btrace2fio: set runtime

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/t/btrace2fio.c b/t/btrace2fio.c
index ef02c69..c88c050 100644
--- a/t/btrace2fio.c
+++ b/t/btrace2fio.c
@@ -532,6 +532,7 @@
 {
 	struct btrace_out *o = &p->o;
 	unsigned long total;
+	unsigned long long time;
 	float perc;
 	int i, j;
 
@@ -585,6 +586,10 @@
 
 	printf("startdelay=%llus\n", o->start_delay / 1000000ULL);
 
+	time = o->last_ttime - o->first_ttime;
+	time = (time + 1000000000ULL - 1) / 1000000000ULL;
+	printf("runtime=%llus\n", time);
+
 	printf("bssplit=");
 	for (i = 0; i < DDIR_RWDIR_CNT; i++) {