[igt-dev] [PATCH i-g-t] tests/perf: Fix timeout for RC6 re-enabling

[Imre Deak]

After closing the perf stream the parking the GPU engines may easily
take more than 1 second: releasing the FD itself results in a new
request submission via i915_perf_release()->i915_oa_stream_destroy()->
gen8_disable_metric_set(). That means a >1sec delay for the delayed
unpark to be called due to the delay from

 queue_delayed_work(retire_work, round_jiffies_up_relative(HZ))

+ the delay from

 mod_delayed_work(idle_work, msecs_to_jiffies(100))

Scheduling may push this delay even further, I measured >2sec delays on
my GLK. Based on this give some slack for the RC6 residency counter to
change.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103179
Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 tests/perf.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tests/perf.c b/tests/perf.c
index 4307d36a..5dc10108 100644
--- a/tests/perf.c
+++ b/tests/perf.c
@@ -3591,6 +3591,7 @@ test_rc6_disable(void)
 	};
 	unsigned long n_events_start, n_events_end;
 	unsigned long rc6_enabled;
+	int i;
 
 	rc6_enabled = 0;
 	igt_sysfs_scanf(sysfs, "power/rc6_enable", "%lu", &rc6_enabled);
@@ -3606,8 +3607,12 @@ test_rc6_disable(void)
 	__perf_close(stream_fd);
 
 	n_events_start = rc6_residency_ms();
-	nanosleep(&(struct timespec){ .tv_sec = 1, .tv_nsec = 0 }, NULL);
-	n_events_end = rc6_residency_ms();
+	for (i = 0; i < 5; i++) {
+		nanosleep(&(struct timespec){ .tv_sec = 1, .tv_nsec = 0 }, NULL);
+		n_events_end = rc6_residency_ms();
+		if (n_events_end != n_events_start)
+			break;
+	}
 	igt_assert_neq(n_events_end - n_events_start, 0);
 }
 
-- 
2.13.2