Re: [kvm-unit-tests PATCH 0/6] arm: pmu: Fix random failures of pmu-chain-promotion

[Eric Auger <eric.auger@redhat.com>]

Hi,

On 3/15/23 12:07, Eric Auger wrote:
> On some HW (ThunderXv2), some random failures of
> pmu-chain-promotion test can be observed.
>
> pmu-chain-promotion is composed of several subtests
> which run 2 mem_access loops. The initial value of
> the counter is set so that no overflow is expected on
> the first loop run and overflow is expected on the second.
> However it is observed that sometimes we get an overflow
> on the first run. It looks related to some variability of
> the mem_acess count. This variability is observed on all
> HW I have access to, with different span though. On
> ThunderX2 HW it looks the margin that is currently taken
> is too small and we regularly hit failure.
>
> although the first goal of this series is to increase
> the count/margin used in those tests, it also attempts
> to improve the pmu-chain-promotion logs, add some barriers
> in the mem-access loop, clarify the chain counter
> enable/disable sequence.
>
> A new 'pmu-memaccess-reliability' is also introduced to
> detect issues with MEM_ACCESS event variability and make
> the debug easier.
>
> Obviously one can wonder if this variability is something normal
> and does not hide any other bug. I hope this series will raise
> additional discussions about this.
>
> https://github.com/eauger/kut/tree/pmu-chain-promotion-fixes-v1

Gentle ping.

Thanks

Eric
>
> Eric Auger (6):
>   arm: pmu: pmu-chain-promotion: Improve debug messages
>   arm: pmu: pmu-chain-promotion: Introduce defines for count and margin
>     values
>   arm: pmu: Add extra DSB barriers in the mem_access loop
>   arm: pmu: Fix chain counter enable/disable sequences
>   arm: pmu: Add pmu-memaccess-reliability test
>   arm: pmu-chain-promotion: Increase the count and margin values
>
>  arm/pmu.c         | 189 +++++++++++++++++++++++++++++++++-------------
>  arm/unittests.cfg |   6 ++
>  2 files changed, 141 insertions(+), 54 deletions(-)
>