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 > workload). 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 hypercalls.) Thanks.
