linux-kernel - Re: [PATCH 0/3] KVM: lapic: optimize injection of already-expired timer

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Message-ID: <CANRm+CxKFDm6z2c5Y+XB=AsZAGPLNPaWjM0ePeiL6gSBX0S8Dw@mail.gmail.com>
Date:   Fri, 30 Jun 2017 09:30:20 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>, Radim Krcmar <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH 0/3] KVM: lapic: optimize injection of already-expired timer

2017-06-30 0:58 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
> This is my take on Wanpeng's optimization, whose effect I've now measured
> with vmexit.flat.  Indeed, without patch 3 the new tscdeadline_immed
> benchmark is 50% slower with preemption_timer=1 than with preemption_timer=0.
>
> Patch 1 refactors start_hv_timer to prepare for the next one and to
> simplify Wanpeng's patch (a lot).  Patch 2 avoids a bug that I didn't
> catch in my earlier review: kvm_x86_ops->set_timer must not be called
> directly when the TSC goes backwards.
>

The patchset looks good to me and thanks for the benchmark.

Regards,
Wanpeng Li

>
> Paolo Bonzini (2):
>   KVM: lapic: reorganize start_hv_timer
>   KVM: lapic: reorganize restart_apic_timer
>
> Wanpeng Li (1):
>   KVM: LAPIC: Fix lapic timer injection delay
>
>  arch/x86/kvm/lapic.c | 116 ++++++++++++++++++++++++++++-----------------------
>  arch/x86/kvm/lapic.h |   2 +-
>  arch/x86/kvm/vmx.c   |   3 +-
>  arch/x86/kvm/x86.c   |   8 ++--
>  4 files changed, 71 insertions(+), 58 deletions(-)
>
> --
> 1.8.3.1
>