Suravee, any inputs? On Tue, 11 Aug 2020 at 16:29, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 11/08/20 04:04, Wanpeng Li wrote: > > We found that the IPI broadcast latency in the guest when AVIC=1, > > exposing xapic is worse than when AVIC=0, exposing xapic. The host is > > AMD ROME, 2 sockets, 96 cores, 192 threads, the VM is 180 vCPUs. The > > guest boots with kvm-hint-dedicated=on, --overcommit cpu-pm=on, -smp > > 180,sockets=2,cores=45,threads=2, l3-cache=on qemu command-line, the > > pCPU which vCPU is running on is isolated. Both the guest and host > > kernel are 5.8 Linus' tree. (Note, if you fails to boot with > > --overcommit cpu-pm=on, you can comments out commit e72436bc3a52, I > > have a report here, https://lkml.org/lkml/2020/7/8/308) > > > > IPI microbenchmark(https://lkml.org/lkml/2017/12/19/141, Destination > > Shorthand is All excluding self) > > > > avic0_xapic: 12313907508.50 ns > > avic1_xapic: 19106424733.30 ns > > avic0_x2apic: 13073988486.00 ns > > I think it depends on the microarchitecture implementation of AVIC? > > Paolo >
