From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Haiwei Li <lihaiwei@tencent.com>
Subject: Re: [PATCH v2] KVM: X86: Ultra fast single target IPI fastpath
Date: Fri, 10 Apr 2020 17:17:23 +0200 [thread overview]
Message-ID: <e639e0f6-9393-7a32-9e2d-13725d7d96f8@redhat.com> (raw)
In-Reply-To: <1586480607-5408-1-git-send-email-wanpengli@tencent.com>
On 10/04/20 03:03, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> IPI and Timer cause the main MSRs write vmexits in cloud environment
> observation, let's optimize virtual IPI latency more aggressively to
> inject target IPI as soon as possible.
>
> Running kvm-unit-tests/vmexit.flat IPI testing on SKX server, disable
> adaptive advance lapic timer and adaptive halt-polling to avoid the
> interference, this patch can give another 7% improvement.
>
> w/o fastpath -> fastpath 4238 -> 3543 16.4%
> fastpath -> ultra fastpath 3543 -> 3293 7%
> w/o fastpath -> ultra fastpath 4238 -> 3293 22.3%
>
> This also revises the performance data in commit 1e9e2622a1 (KVM: VMX:
> FIXED+PHYSICAL mode single target IPI fastpath), that testing adds
> --overcommit cpu-pm=on to kvm-unit-tests guest which is unnecessary.
>
> Tested-by: Haiwei Li <lihaiwei@tencent.com>
> Cc: Haiwei Li <lihaiwei@tencent.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> v1 -> v2:
> * rebase on latest kvm/queue
> * update patch description
>
> arch/x86/include/asm/kvm_host.h | 6 +++---
> arch/x86/kvm/svm/svm.c | 21 ++++++++++++++-------
> arch/x86/kvm/vmx/vmx.c | 19 +++++++++++++------
> arch/x86/kvm/x86.c | 4 ++--
> 4 files changed, 32 insertions(+), 18 deletions(-)
That's less ugly than I expected. :D I'll queue it in the next week or
so. But even though the commit subject is cool, I'll change it to "KVM:
x86: move IPI fastpath inside kvm_x86_ops.run".
Thanks,
Paolo
next prev parent reply other threads:[~2020-04-10 15:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-10 1:03 [PATCH v2] KVM: X86: Ultra fast single target IPI fastpath Wanpeng Li
2020-04-10 15:17 ` Paolo Bonzini [this message]
2020-04-13 1:43 ` Wanpeng Li
2020-04-10 15:35 ` Sean Christopherson
2020-04-10 15:50 ` Paolo Bonzini
2020-04-10 17:47 ` Sean Christopherson
2020-04-10 17:47 ` [PATCH v3 1/2] KVM: VMX: Optimize handling of VM-Entry failures in vmx_vcpu_run() Sean Christopherson
2020-04-10 17:47 ` [PATCH v3 2/2] KVM: X86: Ultra fast single target IPI fastpath Sean Christopherson
2020-04-10 18:43 ` [PATCH v2] " Paolo Bonzini
2020-04-11 0:34 ` Wanpeng Li
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