Commit 6ea85cc7 authored by Chris Wilson's avatar Chris Wilson 🤔

igt/perf_pmu: Bump batch_duration for legacy sampling inaccuracy

Since the legacy ringbuffer uses a sampling technique, it is limited to
an accuracy based on a 200Hz timer, or 5ms. We assert that measurements
are within 5%, so with a 100ms duration that gives us no room for the
systematic error in our sampling. Bump the duration to 500ms to give us
plenty of safety margin (back of the paper estimate is that we need
300ms to provide the accuracy we request for legacy submission), if it
then fails, it should not be due to the sampling!
Signed-off-by: Chris Wilson's avatarChris Wilson <>
Cc: Tvrtko Ursulin <>
Reviewed-by: Tvrtko Ursulin's avatarTvrtko Ursulin <>
parent 374216ee
......@@ -44,7 +44,7 @@
IGT_TEST_DESCRIPTION("Test the i915 pmu perf interface");
const double tolerance = 0.05f;
const unsigned long batch_duration_ns = 100e6;
const unsigned long batch_duration_ns = 500e6;
static int open_pmu(uint64_t config)
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