Re: [PATCH v2 4/5] KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs

Mathieu Desnoyers
2021-08-28T00:06:34Z

----- On Aug 27, 2021, at 7:23 PM, Sean Christopherson seanjc@google.com wrote:

> On Fri, Aug 27, 2021, Mathieu Desnoyers wrote:
[...]
>> Does it reproduce if we randomize the delay to have it picked randomly from 0us
>> to 100us (with 1us step) ? It would remove a lot of the needs for arch-specific
>> magic delay value.
>
> My less-than-scientific testing shows that it can reproduce at delays up to
> ~500us,
> but above ~10us the reproducibility starts to drop. The bug still reproduces
> reliably, it just takes more iterations, and obviously the test runs a bit
> slower.
>
> Any objection to using a 1-10us delay, e.g. a simple usleep((i % 10) + 1)?

Works for me, thanks!

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.