[PATCH] drm/sched: Increase drm_mock_sched_job_wait_finished timeout when CONFIG_HZ=100

[David Gow <david@davidgow.net>]

The drm_sched_scheduler_overhead_tests tests hardcode a timeout of 5x
total_us, and fail if it's exceeded. However, on systems with
CONFIG_HZ < 250, this tends to fail.

As it's possible to configure many architectures to use 100 Hz (and some,
such as UML, hardcode CONFIG_HZ=100), increase the timeout so that the test
doesn't fail on these configurations.

Fixes: 97ef806a5314 ("drm/sched: Add some scheduling quality unit tests")
Signed-off-by: David Gow <david@davidgow.net>
---

This failure showed up on UML when testing the addition of CONFIG_DRM to
the KUnit 'alltests' config[1]. Ideally, I'd like to see this test fixed
(or at least skipped/disabled) on these broken configurations so that the
alltests run is clean. (I don't actually run any CONFIG_HZ=100 configs
other than UML, but fixing them all is ideal if we can manage it.)

If you'd rather a different implementation / magic number, let me know.
I picked 15 here as it gave me plenty of leeway: 10 worked most, but not
all, of the time under i386 qemu w/ CONFIG_HZ_100, and was fine with UML
on this machine.

Thanks,
-- David

[1]: https://lore.kernel.org/all/20260911-kunit-drm-v1-1-c5c0f18fc7b0@kernel.org/
---
 drivers/gpu/drm/scheduler/tests/tests_scheduler.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/tests/tests_scheduler.c b/drivers/gpu/drm/scheduler/tests/tests_scheduler.c
index 285546a2218f..02c83b5c2189 100644
--- a/drivers/gpu/drm/scheduler/tests/tests_scheduler.c
+++ b/drivers/gpu/drm/scheduler/tests/tests_scheduler.c
@@ -13,6 +13,13 @@
  * logic.
  */
 
+/* We need a more generous timeout when CONFIG_HZ=100. */
+#if CONFIG_HZ < 250
+#define TIMEOUT_MULTIPLIER 15
+#else
+#define TIMEOUT_MULTIPLIER 5
+#endif
+
 static int drm_sched_scheduler_init(struct kunit *test)
 {
 	struct drm_mock_scheduler *sched;
@@ -88,7 +95,7 @@ static void drm_sched_scheduler_queue_overhead(struct kunit *test)
 
 	/* Wait with a safe margin to avoid every failing. */
 	done = drm_mock_sched_job_wait_finished(job,
-						usecs_to_jiffies(total_us) * 5);
+						usecs_to_jiffies(total_us) * TIMEOUT_MULTIPLIER);
 	end = ktime_get();
 	KUNIT_ASSERT_TRUE(test, done);
 
@@ -149,7 +156,7 @@ static void drm_sched_scheduler_ping_pong(struct kunit *test)
 
 	/* Wait with a safe margin to avoid every failing. */
 	done = drm_mock_sched_job_wait_finished(job,
-						usecs_to_jiffies(total_us) * 5);
+						usecs_to_jiffies(total_us) * TIMEOUT_MULTIPLIER);
 	end = ktime_get();
 	KUNIT_ASSERT_TRUE(test, done);
 
-- 
2.55.0