Re: [RFC PATCH 0/2] Mitigating Excessive Pause-Loop Exiting in VM-Agnostic KVM

[Wanpeng Li]

On Mon, 26 Apr 2021 at 10:56, Kenta Ishiguro
<kentaishiguro@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Dear all,
>
> Thank you for the insightful feedback.
>
> Does Sean's suggested version of Wanpeng's patch mark a running vCPU as an IPI
> receiver? If it's right, I think the candidate set of vCPUs for boost is
> slightly different between using kvm_arch_interrupt_delivery and using boolean
> ipi_received. In the version of using boolean ipi_received, vCPUs which
> receive IPI while running are also candidates for a boost.
> However, they likely have already responded to their IPI before they exit.

             if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
+                !READ_ONCE(vcpu->ipi_received) &&

There is a vcpu->preempted checking here.

    Wanpeng