Re: [PATCH 14/20] KVM: selftests: Collect *all* dirty entries in each dirty_log_test iteration

Maxim Levitsky
2024-12-19T15:01:38Z

On Thu, 2024-12-19 at 13:55 +0100, Paolo Bonzini wrote:
> On 12/19/24 03:13, Sean Christopherson wrote:
> > On Tue, Dec 17, 2024, Maxim Levitsky wrote:
> > > While this patch might improve coverage for this particular case,
> > > I think that this patch will make the test to be much more deterministic,
> >
> > The verification will be more deterministic, but the actual testcase itself is
> > just as random as it was before.
>
> Based on my recollection of designing this thing with Peter, I can
> "confirm" that there was no particular intention of making the
> verification more random.
>
> > > and thus have less chance of catching various races in the kernel that can happen.
> > >
> > > In fact in my option I prefer moving this test in other direction by
> > > verifying dirty ring while the *vCPU runs* as well, in other words, not
> > > stopping the vCPU at all unless its dirty ring is full.
> >
> > But letting the vCPU-under-test keep changing the memory while it's being validated
> > would add significant complexity, without any benefit insofar as I can see. As
> > evidenced by the bug the current approach can't detect, heavily stressing the
> > system is meaningless if it's impossible to separate the signal from the noise.
>
> Yes, I agree.
>
> Paolo
>

In this case I don't have any objections.

Best regards,
Maxim Levitsky