Recent CI failures brought my attention to the fact that pmu_counters_test
sometimes fails because it doesn't get any LLC cache misses.
It apparently happens because CLFLUSH can race with CPU prediction.
To attempt to fix this, implement a more aggressive cache flushing - now it is flushed
on each iteration of the measured loop which should at least reduce by order
of magnitude the chance of this happening.
This patch survived more that a day of running in a loop on a Comet Lake machine,
where the test used to fail after about 10-20 minites.
Best regards,
Maxim Levitsky
Maxim Levitsky (1):
KVM: selftests: pmu_counters_test: increase robustness of LLC cache
misses
.../selftests/kvm/x86_64/pmu_counters_test.c | 20 +++++++++----------
1 file changed, 9 insertions(+), 11 deletions(-)
--
2.26.3
