linux-kernel - Re: [PATCH] KVM: VMX: Micro-optimize vmexit time when not exposing PMU

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Message-ID: <877dzor5am.fsf@vitty.brq.redhat.com>
Date:   Fri, 13 Mar 2020 10:08:01 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>, Wanpeng Li <kernellwp@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH] KVM: VMX: Micro-optimize vmexit time when not exposing PMU

Jim Mattson <jmattson@...gle.com> writes:

> On Thu, Mar 12, 2020 at 3:36 AM Vitaly Kuznetsov <vkuznets@...hat.com> wrote:
>
>> Also, speaking about cloud providers and the 'micro' nature of this
>> optimization, would it rather make sense to introduce a static branch
>> (the policy to disable vPMU is likely to be host wide, right)?
>
> Speaking for a cloud provider, no, the policy is not likely to be host-wide.

Ah, then it's just my flawed picture of the world where hosts only run
instances of the same type/family because it's mych easier to partition
them this way.

Scratch the static branch idea then.

-- 
Vitaly