From: David Matlack <dmatlack@google.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] KVM: x86/mmu: Buffer nested MMU split_desc_cache only by default capacity
Date: Fri, 24 Jun 2022 17:39:30 +0000 [thread overview]
Message-ID: <YrX20hfudgMQ/6ns@google.com> (raw)
In-Reply-To: <20220624171808.2845941-4-seanjc@google.com>
On Fri, Jun 24, 2022 at 05:18:08PM +0000, Sean Christopherson wrote:
> Buffer split_desc_cache, the cache used to allcoate rmap list entries,
> only by the default cache capacity (currently 40), not by doubling the
> minimum (513). Aliasing L2 GPAs to L1 GPAs is uncommon, thus eager page
> splitting is unlikely to need 500+ entries. And because each object is a
> non-trivial 128 bytes (see struct pte_list_desc), those extra ~500
> entries means KVM is in all likelihood wasting ~64kb of memory per VM.
>
> Link: https://lore.kernel.org/all/YrTDcrsn0%2F+alpzf@google.com
> Cc: David Matlack <dmatlack@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Thanks for the cleanups!
Reviewed-by: David Matlack <dmatlack@google.com>
next prev parent reply other threads:[~2022-06-24 17:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 17:18 [PATCH 0/3] KVM: x86/mmu: Cleanups for eager page splitting Sean Christopherson
2022-06-24 17:18 ` [PATCH 1/3] KVM: x86/mmu: Avoid subtle pointer arithmetic in kvm_mmu_child_role() Sean Christopherson
2022-06-24 17:33 ` David Matlack
2022-06-24 18:50 ` Sean Christopherson
2022-06-24 17:18 ` [PATCH 2/3] KVM: x86/mmu: Use "unsigned int", not "u32", for SPTEs' @access info Sean Christopherson
2022-06-24 17:38 ` David Matlack
2022-06-24 17:18 ` [PATCH 3/3] KVM: x86/mmu: Buffer nested MMU split_desc_cache only by default capacity Sean Christopherson
2022-06-24 17:39 ` David Matlack [this message]
2022-06-25 8:55 ` [PATCH 0/3] KVM: x86/mmu: Cleanups for eager page splitting Paolo Bonzini
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