Re: [PATCH v10 0/3] Per-vCPU dirty quota-based throttling

Marc Zyngier
2024-04-04T09:20:01Z

On Thu, 21 Mar 2024 05:48:01 +0000,
Shivam Kumar <shivam.kumar1@nutanix.com> wrote:
>
>
> > On 22-Feb-2024, at 1:22 AM, Shivam Kumar <shivam.kumar1@nutanix.com> wrote:
> >
> > The current v10 patchset includes the following changes over v9:
> >
> > 1. Use vma_pagesize as the dirty granularity for updating dirty quota
> > on arm64.
> > 2. Do not update dirty quota for instances where the hypervisor is
> > writing into guest memory. Accounting for these instances in vCPUs'
> > dirty quota is unfair to the vCPUs. Also, some of these instances,
> > such as record_steal_time, frequently try to redundantly mark the same
> > set of pages dirty again and again. To avoid these distortions, we had
> > previously relied on checking the dirty bitmap to avoid redundantly
> > updating quotas. Since we have now decoupled dirty-quota-based
> > throttling from the live-migration dirty-tracking path, we have
> > resolved this issue by simply avoiding the mis-accounting caused by
> > these hypervisor-induced writes to guest memory. Through extensive
> > experiments, we have verified that this new approach is approximately
> > as effective as the prior approach that relied on checking the dirty
> > bitmap.
> >
>
> Hi Marc,
>
> I’ve tried my best to address all the concerns raised in the
> previous patchset. I’d really appreciate it if you could share your
> thoughts and any feedback you might have on this one.

I'll get to it at some point. However, given that it has you taken the
best part of a year to respin this, I need to page it all back it,
which is going to take a bit of time as well.

Thanks,

M.

--
Without deviation from the norm, progress is not possible.