From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, x86@kernel.org,
"Radim Krčmář" <rkrcmar@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>,
"Mohammed Gamal" <mmorsy@redhat.com>,
"Cathy Avery" <cavery@redhat.com>, "Bandan Das" <bsd@redhat.com>,
"Roman Kagan" <rkagan@virtuozzo.com>,
linux-kernel@vger.kernel.org, devel@linuxdriverproject.org
Subject: Re: [PATCH RFC 0/7] KVM: nVMX: enlightened VMCS initial implementation
Date: Thu, 21 Dec 2017 15:32:14 +0100 [thread overview]
Message-ID: <c5c1357d-c36a-38bf-6148-8ffb89a0290b@redhat.com> (raw)
In-Reply-To: <87vah0w8h9.fsf@vitty.brq.redhat.com>
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
next prev parent reply other threads:[~2017-12-21 14:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-18 17:17 Vitaly Kuznetsov
2017-12-18 17:17 ` [PATCH RFC 1/7] KVM: x86: rename HV_X64_MSR_APIC_ASSIST_PAGE to HV_X64_MSR_VP_ASSIST_PAGE Vitaly Kuznetsov
2017-12-18 17:17 ` [PATCH RFC 2/7] KVM: nVMX: modify vmcs12 fields to match Hyper-V enlightened VMCS Vitaly Kuznetsov
2017-12-18 20:23 ` Jim Mattson
2017-12-18 21:28 ` Jim Mattson
2017-12-19 12:25 ` Vitaly Kuznetsov
2017-12-19 12:37 ` Paolo Bonzini
2017-12-19 17:40 ` Jim Mattson
2017-12-19 21:19 ` Paolo Bonzini
2017-12-21 13:02 ` Vitaly Kuznetsov
2017-12-19 17:44 ` Jim Mattson
2017-12-18 17:17 ` [PATCH RFC 3/7] KVM: nVMX: add I/O exit ECX, ESI, EDI, EIP vmcs12 fields Vitaly Kuznetsov
2017-12-18 17:17 ` [PATCH RFC 4/7] KVM: hyperv: define VP assist page structure and add helpers Vitaly Kuznetsov
2017-12-18 17:17 ` [PATCH RFC 5/7] KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability Vitaly Kuznetsov
2017-12-18 17:17 ` [PATCH RFC 6/7] KVM: nVMX: add enlightened VMCS state Vitaly Kuznetsov
2017-12-18 17:17 ` [PATCH RFC 7/7] KVM: nVMX: implement enlightened VMPTRLD Vitaly Kuznetsov
2017-12-19 12:41 ` [PATCH RFC 0/7] KVM: nVMX: enlightened VMCS initial implementation Paolo Bonzini
2017-12-19 13:21 ` Vitaly Kuznetsov
2017-12-21 12:50 ` Vitaly Kuznetsov
2017-12-21 14:32 ` Paolo Bonzini [this message]
2017-12-21 15:08 ` Vitaly Kuznetsov
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