[igt-dev] [PATCH i-g-t] tests/perf: dramatically loosen expectations on oa-exponents

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

This test really quite flaky because it expects HW to emit reports
following pretty much exactly the specified timer. And there are lots
of reasons the HW might not be able to meet the timer deadline. The
design is such that it's expected to not always meet the timer.

We just want to verify that the HW was configured properly, so loosen
the checks to half the reports (of 30) meeting the timer deadline.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
---
 tests/perf.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tests/perf.c b/tests/perf.c
index 442d89fb..023829fc 100644
--- a/tests/perf.c
+++ b/tests/perf.c
@@ -1742,8 +1742,14 @@ test_oa_exponents(void)
 
 		igt_debug("matches=%u/%u\n", matches, n_timer_reports - 1);
 
-		/* Allow for a couple of errors. */
-		igt_assert_lte(n_timer_reports - 3, matches);
+		/*
+		 * Expect half the reports to match the timing
+		 * expectation. The results are quite erratic because
+		 * the condition under which the HW reaches
+		 * expectations depends on memory controller pressure
+		 * etc...
+		 */
+		igt_assert_lte(n_timer_reports / 2, matches);
 	}
 
 	load_helper_stop();
-- 
2.26.0

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