[igt-dev] [PATCH v2] 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.

Fix this by calling gem_quiescent_gpu() which syncs up with the idle
work, thus making sure we'll see RC6 residency afterwards.

v2:
- Use gem_quiescent_gpu() instead of increasing the timeout. (Chris)

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 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/perf.c b/tests/perf.c
index 4307d36a..f2c0aeb8 100644
--- a/tests/perf.c
+++ b/tests/perf.c
@@ -3604,6 +3604,7 @@ test_rc6_disable(void)
 	igt_assert_eq(n_events_end - n_events_start, 0);
 
 	__perf_close(stream_fd);
+	gem_quiescent_gpu(drm_fd);
 
 	n_events_start = rc6_residency_ms();
 	nanosleep(&(struct timespec){ .tv_sec = 1, .tv_nsec = 0 }, NULL);
-- 
2.13.2