| Message ID | 20220429201131.3397875-4-yosryahmed@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: mm: count KVM mmu usage in memory stats | expand |
On Fri, Apr 29, 2022, Yosry Ahmed wrote: > Count the pages used by KVM mmu on x86 for in secondary pagetable stats. > > For the legacy mmu, accounting pagetable stats is combined KVM's > existing for mmu pages in newly introduced kvm_[un]account_mmu_page() > helpers. > > For tdp mmu, introduce new tdp_[un]account_mmu_page() helpers. That > combines accounting pagetable stats with the tdp_mmu_pages counter > accounting. > > tdp_mmu_pages counter introduced in this series [1]. This patch was > rebased on top of the first two patches in that series. > > [1]https://lore.kernel.org/lkml/20220401063636.2414200-1-mizhang@google.com/ > > Signed-off-by: Yosry Ahmed <yosryahmed@google.com> > --- It looks like there are two metrics for mmu in x86: one for shadow mmu and the other for TDP mmu. Is there any plan to merge them together? > arch/x86/kvm/mmu/mmu.c | 16 ++++++++++++++-- > arch/x86/kvm/mmu/tdp_mmu.c | 16 ++++++++++++++-- > 2 files changed, 28 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 78d8e1d8fb99..e5b0e826445d 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -1679,6 +1679,18 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr) > percpu_counter_add(&kvm_total_used_mmu_pages, nr); > } > > +static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) > +{ > + kvm_mod_used_mmu_pages(kvm, +1); > + kvm_account_pgtable_pages((void *)sp->spt, +1); > +} > + > +static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) > +{ > + kvm_mod_used_mmu_pages(kvm, -1); > + kvm_account_pgtable_pages((void *)sp->spt, -1); > +} > + > static void kvm_mmu_free_page(struct kvm_mmu_page *sp) > { > MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); > @@ -1734,7 +1746,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct > */ > sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen; > list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages); > - kvm_mod_used_mmu_pages(vcpu->kvm, +1); > + kvm_account_mmu_page(vcpu->kvm, sp); > return sp; > } > > @@ -2363,7 +2375,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, > list_add(&sp->link, invalid_list); > else > list_move(&sp->link, invalid_list); > - kvm_mod_used_mmu_pages(kvm, -1); > + kvm_unaccount_mmu_page(kvm, sp); > } else { > /* > * Remove the active root from the active page list, the root > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 3456277ade18..6295c4da5dee 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -371,6 +371,18 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, > } > } > > +static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) > +{ > + atomic64_inc(&kvm->arch.tdp_mmu_pages); > + kvm_account_pgtable_pages((void *)sp->spt, +1); > +} > + > +static void tdp_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) > +{ > + atomic64_dec(&kvm->arch.tdp_mmu_pages); > + kvm_account_pgtable_pages((void *)sp->spt, -1); > +} > + > /** > * tdp_mmu_unlink_sp() - Remove a shadow page from the list of used pages > * > @@ -383,7 +395,7 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, > static void tdp_mmu_unlink_sp(struct kvm *kvm, struct kvm_mmu_page *sp, > bool shared) > { > - atomic64_dec(&kvm->arch.tdp_mmu_pages); > + tdp_unaccount_mmu_page(kvm, sp); > > if (!sp->lpage_disallowed) > return; > @@ -1121,7 +1133,7 @@ static int tdp_mmu_link_sp(struct kvm *kvm, struct tdp_iter *iter, > tdp_mmu_set_spte(kvm, iter, spte); > } > > - atomic64_inc(&kvm->arch.tdp_mmu_pages); > + tdp_account_mmu_page(kvm, sp); > > return 0; > } > -- > 2.36.0.464.gb9c8b46e94-goog >
On Fri, Jul 22, 2022, Mingwei Zhang wrote: > On Fri, Apr 29, 2022, Yosry Ahmed wrote: > > Count the pages used by KVM mmu on x86 for in secondary pagetable stats. > > > > For the legacy mmu, accounting pagetable stats is combined KVM's > > existing for mmu pages in newly introduced kvm_[un]account_mmu_page() > > helpers. > > > > For tdp mmu, introduce new tdp_[un]account_mmu_page() helpers. That > > combines accounting pagetable stats with the tdp_mmu_pages counter > > accounting. > > > > tdp_mmu_pages counter introduced in this series [1]. This patch was > > rebased on top of the first two patches in that series. > > > > [1]https://lore.kernel.org/lkml/20220401063636.2414200-1-mizhang@google.com/ > > > > Signed-off-by: Yosry Ahmed <yosryahmed@google.com> > > --- > > It looks like there are two metrics for mmu in x86: one for shadow mmu > and the other for TDP mmu. Is there any plan to merge them together? There aren't two _separate_ metrics per se, rather that the TDP MMU (intentionally) doesn't honor KVM_SET_NR_MMU_PAGES, nor does it play nice the the core mm shrinkers. Thus, the TDP MMU doesn't udpate kvm_mod_used_mmu_pages(), which feeds into both of those things. Long term, I don't think the TDP MMU will ever honor KVM_SET_NR_MMU_PAGES. That particular knob predates proper integration with memcg and probably should be deprecated. As for supporting shrinkers in the TDP MMU, it's unclear whether or not that's truly necessary. And until mmu_shrink_scan() is made a _lot_ smarter, it's somewhat of a moot point because KVM's shrinker implementation is just too naive for it to be a net positive, e.g. it tends to zap upper level entries and wipe out large swaths of KVM's page tables. KVM_SET_NR_MMU_PAGES uses the same naive algorithm, so it's not any better.
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 78d8e1d8fb99..e5b0e826445d 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1679,6 +1679,18 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr) percpu_counter_add(&kvm_total_used_mmu_pages, nr); } +static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_mod_used_mmu_pages(kvm, +1); + kvm_account_pgtable_pages((void *)sp->spt, +1); +} + +static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_mod_used_mmu_pages(kvm, -1); + kvm_account_pgtable_pages((void *)sp->spt, -1); +} + static void kvm_mmu_free_page(struct kvm_mmu_page *sp) { MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); @@ -1734,7 +1746,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct */ sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen; list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages); - kvm_mod_used_mmu_pages(vcpu->kvm, +1); + kvm_account_mmu_page(vcpu->kvm, sp); return sp; } @@ -2363,7 +2375,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, list_add(&sp->link, invalid_list); else list_move(&sp->link, invalid_list); - kvm_mod_used_mmu_pages(kvm, -1); + kvm_unaccount_mmu_page(kvm, sp); } else { /* * Remove the active root from the active page list, the root diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 3456277ade18..6295c4da5dee 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -371,6 +371,18 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, } } +static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + atomic64_inc(&kvm->arch.tdp_mmu_pages); + kvm_account_pgtable_pages((void *)sp->spt, +1); +} + +static void tdp_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + atomic64_dec(&kvm->arch.tdp_mmu_pages); + kvm_account_pgtable_pages((void *)sp->spt, -1); +} + /** * tdp_mmu_unlink_sp() - Remove a shadow page from the list of used pages * @@ -383,7 +395,7 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, static void tdp_mmu_unlink_sp(struct kvm *kvm, struct kvm_mmu_page *sp, bool shared) { - atomic64_dec(&kvm->arch.tdp_mmu_pages); + tdp_unaccount_mmu_page(kvm, sp); if (!sp->lpage_disallowed) return; @@ -1121,7 +1133,7 @@ static int tdp_mmu_link_sp(struct kvm *kvm, struct tdp_iter *iter, tdp_mmu_set_spte(kvm, iter, spte); } - atomic64_inc(&kvm->arch.tdp_mmu_pages); + tdp_account_mmu_page(kvm, sp); return 0; }
Count the pages used by KVM mmu on x86 for in secondary pagetable stats. For the legacy mmu, accounting pagetable stats is combined KVM's existing for mmu pages in newly introduced kvm_[un]account_mmu_page() helpers. For tdp mmu, introduce new tdp_[un]account_mmu_page() helpers. That combines accounting pagetable stats with the tdp_mmu_pages counter accounting. tdp_mmu_pages counter introduced in this series [1]. This patch was rebased on top of the first two patches in that series. [1]https://lore.kernel.org/lkml/20220401063636.2414200-1-mizhang@google.com/ Signed-off-by: Yosry Ahmed <yosryahmed@google.com> --- arch/x86/kvm/mmu/mmu.c | 16 ++++++++++++++-- arch/x86/kvm/mmu/tdp_mmu.c | 16 ++++++++++++++-- 2 files changed, 28 insertions(+), 4 deletions(-)