From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Peter Shier <pshier@google.com>,
David Matlack <dmatlack@google.com>,
Mingwei Zhang <mizhang@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
Kai Huang <kai.huang@intel.com>,
Keqian Zhu <zhukeqian1@huawei.com>,
David Hildenbrand <david@redhat.com>,
Ben Gardon <bgardon@google.com>
Subject: [RFC 00/19] KVM: x86/mmu: Optimize disabling dirty logging
Date: Wed, 10 Nov 2021 14:29:51 -0800 [thread overview]
Message-ID: <20211110223010.1392399-1-bgardon@google.com> (raw)
Currently disabling dirty logging with the TDP MMU is extremely slow.
On a 96 vCPU / 96G VM it takes ~45 seconds to disable dirty logging
with the TDP MMU, as opposed to ~3.5 seconds with the legacy MMU. This
series optimizes TLB flushes and introduces in-place large page
promotion, to bring the disable dirty log time down to ~2 seconds.
Testing:
Ran KVM selftests and kvm-unit-tests on an Intel Skylake. This
series introduced no new failures.
Performance:
To collect these results I needed to apply Mingwei's patch
"selftests: KVM: align guest physical memory base address to 1GB"
https://lkml.org/lkml/2021/8/29/310
David Matlack is going to send out an updated version of that patch soon.
Without this series, TDP MMU:
> ./dirty_log_perf_test -v 96 -s anonymous_hugetlb_1gb
Test iterations: 2
Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages
guest physical test memory offset: 0x3fe7c0000000
Populate memory time: 10.966500447s
Enabling dirty logging time: 0.002068737s
Iteration 1 dirty memory time: 0.047556280s
Iteration 1 get dirty log time: 0.001253914s
Iteration 1 clear dirty log time: 0.049716661s
Iteration 2 dirty memory time: 3.679662016s
Iteration 2 get dirty log time: 0.000659546s
Iteration 2 clear dirty log time: 1.834329322s
Disabling dirty logging time: 45.738439510s
Get dirty log over 2 iterations took 0.001913460s. (Avg 0.000956730s/iteration)
Clear dirty log over 2 iterations took 1.884045983s. (Avg 0.942022991s/iteration)
Without this series, Legacy MMU:
> ./dirty_log_perf_test -v 96 -s anonymous_hugetlb_1gb
Test iterations: 2
Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages
guest physical test memory offset: 0x3fe7c0000000
Populate memory time: 12.664750666s
Enabling dirty logging time: 0.002025510s
Iteration 1 dirty memory time: 0.046240875s
Iteration 1 get dirty log time: 0.001864342s
Iteration 1 clear dirty log time: 0.170243637s
Iteration 2 dirty memory time: 31.571088701s
Iteration 2 get dirty log time: 0.000626245s
Iteration 2 clear dirty log time: 1.294817729s
Disabling dirty logging time: 3.566831573s
Get dirty log over 2 iterations took 0.002490587s. (Avg 0.001245293s/iteration)
Clear dirty log over 2 iterations took 1.465061366s. (Avg 0.732530683s/iteration)
With this series, TDP MMU:
> ./dirty_log_perf_test -v 96 -s anonymous_hugetlb_1gb
Test iterations: 2
Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages
guest physical test memory offset: 0x3fe7c0000000
Populate memory time: 12.016653537s
Enabling dirty logging time: 0.001992860s
Iteration 1 dirty memory time: 0.046701599s
Iteration 1 get dirty log time: 0.001214806s
Iteration 1 clear dirty log time: 0.049519923s
Iteration 2 dirty memory time: 3.581931268s
Iteration 2 get dirty log time: 0.000621383s
Iteration 2 clear dirty log time: 1.894597059s
Disabling dirty logging time: 1.950542092s
Get dirty log over 2 iterations took 0.001836189s. (Avg 0.000918094s/iteration)
Clear dirty log over 2 iterations took 1.944116982s. (Avg 0.972058491s/iteration)
Patch breakdown:
Patch 1 is a fix for a bug in the way the TBP MMU issues TLB flushes
Patches 2-5 eliminate many unnecessary TLB flushes through better batching
Patches 6-12 remove the need for a vCPU pointer to make_spte
Patches 13-18 are small refactors in perparation for patch 19
Patch 19 implements in-place largepage promotion when disabling dirty logging
Ben Gardon (19):
KVM: x86/mmu: Fix TLB flush range when handling disconnected pt
KVM: x86/mmu: Batch TLB flushes for a single zap
KVM: x86/mmu: Factor flush and free up when zapping under MMU write
lock
KVM: x86/mmu: Yield while processing disconnected_sps
KVM: x86/mmu: Remove redundant flushes when disabling dirty logging
KVM: x86/mmu: Introduce vcpu_make_spte
KVM: x86/mmu: Factor wrprot for nested PML out of make_spte
KVM: x86/mmu: Factor mt_mask out of make_spte
KVM: x86/mmu: Remove need for a vcpu from
kvm_slot_page_track_is_active
KVM: x86/mmu: Remove need for a vcpu from mmu_try_to_unsync_pages
KVM: x86/mmu: Factor shadow_zero_check out of make_spte
KVM: x86/mmu: Replace vcpu argument with kvm pointer in make_spte
KVM: x86/mmu: Factor out the meat of reset_tdp_shadow_zero_bits_mask
KVM: x86/mmu: Propagate memslot const qualifier
KVM: x86/MMU: Refactor vmx_get_mt_mask
KVM: x86/mmu: Factor out part of vmx_get_mt_mask which does not depend
on vcpu
KVM: x86/mmu: Add try_get_mt_mask to x86_ops
KVM: x86/mmu: Make kvm_is_mmio_pfn usable outside of spte.c
KVM: x86/mmu: Promote pages in-place when disabling dirty logging
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/include/asm/kvm_page_track.h | 6 +-
arch/x86/kvm/mmu/mmu.c | 45 +++---
arch/x86/kvm/mmu/mmu_internal.h | 6 +-
arch/x86/kvm/mmu/page_track.c | 8 +-
arch/x86/kvm/mmu/paging_tmpl.h | 6 +-
arch/x86/kvm/mmu/spte.c | 43 +++--
arch/x86/kvm/mmu/spte.h | 17 +-
arch/x86/kvm/mmu/tdp_mmu.c | 217 +++++++++++++++++++++-----
arch/x86/kvm/mmu/tdp_mmu.h | 5 +-
arch/x86/kvm/svm/svm.c | 8 +
arch/x86/kvm/vmx/vmx.c | 40 +++--
include/linux/kvm_host.h | 10 +-
virt/kvm/kvm_main.c | 12 +-
15 files changed, 302 insertions(+), 124 deletions(-)
--
2.34.0.rc0.344.g81b53c2807-goog
next reply other threads:[~2021-11-10 22:30 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-10 22:29 Ben Gardon [this message]
2021-11-10 22:29 ` [RFC 01/19] KVM: x86/mmu: Fix TLB flush range when handling disconnected pt Ben Gardon
2021-11-11 17:44 ` David Matlack
2021-11-10 22:29 ` [RFC 02/19] KVM: x86/mmu: Batch TLB flushes for a single zap Ben Gardon
2021-11-11 18:06 ` David Matlack
2021-11-12 23:53 ` Sean Christopherson
2021-11-10 22:29 ` [RFC 03/19] KVM: x86/mmu: Factor flush and free up when zapping under MMU write lock Ben Gardon
2021-11-11 18:31 ` David Matlack
2021-11-10 22:29 ` [RFC 04/19] KVM: x86/mmu: Yield while processing disconnected_sps Ben Gardon
2021-11-11 18:50 ` David Matlack
2021-11-10 22:29 ` [RFC 05/19] KVM: x86/mmu: Remove redundant flushes when disabling dirty logging Ben Gardon
2021-11-11 18:55 ` David Matlack
2021-11-10 22:29 ` [RFC 06/19] KVM: x86/mmu: Introduce vcpu_make_spte Ben Gardon
2021-11-10 22:29 ` [RFC 07/19] KVM: x86/mmu: Factor wrprot for nested PML out of make_spte Ben Gardon
2021-11-18 2:12 ` Sean Christopherson
2021-11-18 17:43 ` Ben Gardon
2021-11-18 18:04 ` Paolo Bonzini
2021-11-10 22:29 ` [RFC 08/19] KVM: x86/mmu: Factor mt_mask " Ben Gardon
2021-11-10 22:30 ` [RFC 09/19] KVM: x86/mmu: Remove need for a vcpu from kvm_slot_page_track_is_active Ben Gardon
2021-11-10 22:30 ` [RFC 10/19] KVM: x86/mmu: Remove need for a vcpu from mmu_try_to_unsync_pages Ben Gardon
2021-11-10 22:30 ` [RFC 11/19] KVM: x86/mmu: Factor shadow_zero_check out of make_spte Ben Gardon
2021-11-10 22:44 ` Paolo Bonzini
2021-11-10 23:49 ` Ben Gardon
2021-11-11 1:18 ` Sean Christopherson
2021-11-11 1:44 ` Sean Christopherson
2021-11-11 7:06 ` Paolo Bonzini
2021-11-18 2:05 ` Sean Christopherson
2021-11-18 3:29 ` Sean Christopherson
2021-11-18 16:37 ` Sean Christopherson
2021-11-18 17:19 ` Paolo Bonzini
2021-11-18 18:02 ` Sean Christopherson
2021-11-18 18:07 ` Paolo Bonzini
2021-11-18 18:14 ` Sean Christopherson
2021-11-10 22:30 ` [RFC 12/19] KVM: x86/mmu: Replace vcpu argument with kvm pointer in make_spte Ben Gardon
2021-11-10 22:30 ` [RFC 13/19] KVM: x86/mmu: Factor out the meat of reset_tdp_shadow_zero_bits_mask Ben Gardon
2021-11-10 22:30 ` [RFC 14/19] KVM: x86/mmu: Propagate memslot const qualifier Ben Gardon
2021-11-10 22:30 ` [RFC 15/19] KVM: x86/MMU: Refactor vmx_get_mt_mask Ben Gardon
2021-11-10 22:30 ` [RFC 16/19] KVM: x86/mmu: Factor out part of vmx_get_mt_mask which does not depend on vcpu Ben Gardon
2021-11-10 22:30 ` [RFC 17/19] KVM: x86/mmu: Add try_get_mt_mask to x86_ops Ben Gardon
2021-11-10 22:30 ` [RFC 18/19] KVM: x86/mmu: Make kvm_is_mmio_pfn usable outside of spte.c Ben Gardon
2021-11-10 22:30 ` [RFC 19/19] KVM: x86/mmu: Promote pages in-place when disabling dirty logging Ben Gardon
2021-11-15 21:24 ` [RFC 00/19] KVM: x86/mmu: Optimize " Ben Gardon
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