[Piglit] [PATCH] ext_timer_query-time-elapsed: make results more reliable

[Vadim Girlin]

The test results aren't very reliable depending on the current cpu/gpu load
etc, so it fails sometimes with r600g. AFAICS it's not expected to be running
concurrently with other apps/tests.

We can decrease the effect of high cpu load by using clock() instead of
gettimeofday().
---

The problem is reproducible for me with r600g and ~10 of 
"vblank_mode=0 glxgears" running in parallel - 10 of 10 test runs failed.
With this patch 10 of 10 test runs passed.

 tests/spec/ext_timer_query/time-elapsed.c | 21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/tests/spec/ext_timer_query/time-elapsed.c b/tests/spec/ext_timer_query/time-elapsed.c
index ce27ce0..9350ca9 100644
--- a/tests/spec/ext_timer_query/time-elapsed.c
+++ b/tests/spec/ext_timer_query/time-elapsed.c
@@ -29,7 +29,7 @@
  * Test TIME_ELAPSED and TIMESTAMP queries.
  */
 
-#include <sys/time.h>
+#include <time.h>
 
 PIGLIT_GL_TEST_MAIN(
     128 /*window_width*/,
@@ -44,23 +44,8 @@ enum {
 static float
 get_time(void)
 {
-	static bool inited = false;
-	static time_t base_sec = 0;
-	struct timeval tv;
-
-	gettimeofday(&tv, NULL);
-
-	/* Return a value that is roughly seconds since program
-	 * startup, to avoid large tv_sec reducing precision of the
-	 * return value.
-	 */
-	if (!inited) {
-		inited = true;
-		base_sec = tv.tv_sec;
-	}
-	tv.tv_sec -= base_sec;
-
-	return (double)tv.tv_sec + tv.tv_usec / 1000000.0;
+	clock_t clk = clock();
+	return ((double)clk) / CLOCKS_PER_SEC;
 }
 
 static float
-- 
1.7.11.4