Re: [PATCH v3 0/3] KVM: Yield to IPI target if necessary
From: Radim KrÄmÃÅ
Date: Mon Jun 10 2019 - 10:38:47 EST
2019-05-30 09:05+0800, Wanpeng Li:
> The idea is from Xen, when sending a call-function IPI-many to vCPUs,
> yield if any of the IPI target vCPUs was preempted. 17% performance
> increasement of ebizzy benchmark can be observed in an over-subscribe
> environment. (w/ kvm-pv-tlb disabled, testing TLB flush call-function
> IPI-many since call-function is not easy to be trigged by userspace
Have you checked if we could gain performance by having the yield as an
extension to our PV IPI call?
It would allow us to skip the VM entry/exit overhead on the caller.
(The benefit of that might be negligible and it also poses a
complication when splitting the target mask into several PV IPI