linux-kernel - Re: [PATCH 0/3] avoid unnecessary memslot rmap walks

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Message-ID: <2d440118-4325-6f68-75e7-dd5a74c4a7eb@redhat.com>
Date:   Thu, 4 Jun 2020 20:42:49 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Anthony Yznaga <anthony.yznaga@...cle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, steven.sistare@...cle.com
Subject: Re: [PATCH 0/3] avoid unnecessary memslot rmap walks

On 02/06/20 22:07, Anthony Yznaga wrote:
> While investigating optimizing qemu start time for large memory guests
> I found that kvm_mmu_slot_apply_flags() is walking rmaps to update
> existing sptes when creating or moving a slot but that there won't be
> any existing sptes to update and any sptes inserted once the new memslot
> is visible won't need updating.  I can't find any reason for this not to
> be the case, but I've taken a more cautious approach to fixing this by
> dividing things into three patches.
> 
> Anthony Yznaga (3):
>   KVM: x86: remove unnecessary rmap walk of read-only memslots
>   KVM: x86: avoid unnecessary rmap walks when creating/moving slots
>   KVM: x86: minor code refactor and comments fixup around dirty logging
> 
>  arch/x86/kvm/x86.c | 106 +++++++++++++++++++++++++----------------------------
>  1 file changed, 49 insertions(+), 57 deletions(-)
> 

Queued, thanks.

Paolo