Messages in this thread |  | | Subject | Re: [PATCH RFC 0/7] KVM: nVMX: enlightened VMCS initial implementation | From | Paolo Bonzini <> | Date | Thu, 21 Dec 2017 15:32:14 +0100 |
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On 21/12/2017 13:50, Vitaly Kuznetsov wrote: > I'm back with (somewhat frustrating) results (E5-2603):
v4 (that would be Broadwell)?
> 1) Windows on Hyper-V (no nesting): 1350 cycles > > 2) Windows on Hyper-V on Hyper-V: 8600 > > 3) Windows on KVM (no nesting): 1150 cycles > > 4) Windows on Hyper-V on KVM (no enlightened VMCS): 18200 > > 5) Windows on Hyper-V on KVM (enlightened VMCS): 17100
What version were you using for KVM? There are quite a few nested virt optimizations in kvm/queue (which may make enlightened VMCS both more or less efficient).
In particular, with latest kvm/queue you could try tracing vmread and vmwrite vmexits, and see if you get any. If you do, that might be an easy few hundred cycles savings.
Paolo
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