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bh=qyi+M/saklCNQuq1I1rszMvXi6AUE7MTwewUZQVjzno=; b=EYkdD6ATDKlA/Z9LMxj+VqEYBbSeRU/UXwKS6aZqEDNHut6KQSRehNI1jH5/qrxPSy WDGDXKkddxePf/28uECTqh4nAn8QHnEaVSw6O2bXilRXvbpuPxVp6gwaG1AGvpcDVXju TUBlSdVesCglTLCqN27Jyfaf6ivKPz4owOG2JQtpzA/ju7T2Z8jwxPN8pqYxQAJt1z1f S+idQIzVNy2ZoBYDYamNjT7KrhSoOmVRR7Efc1SFHnBsL5B13kslTHTSeJV5ltSFygSQ UDi55h00N8C5DYJP0Exg/6OlN9jpFl4FGg5KKr60JXWMFea3okM4otLDoKRiO+30CE5v MCPw== X-Gm-Message-State: AOAM533WgqwTlCChdSSRYZ+qUcORPg9orAPXKfSvuPyeEFOqIbpLriKl TVJ28GVEdscBBhHiCFXYZ8+exDr9HEK8Eh/Wx0ns9A== X-Google-Smtp-Source: ABdhPJx3wgfikXxmgQH5PTXeIJMiJ46hAKS29nuMDO7doSxXS5Kcm+WNl5Vvog5LWhMkFcQWvQibkVNvmvXIoSK62yc= X-Received: by 2002:a17:90b:228c:: with SMTP id kx12mr34103653pjb.38.1628635500021; Tue, 10 Aug 2021 15:45:00 -0700 (PDT) MIME-Version: 1.0 References: <20210810223238.979194-1-jingzhangos@google.com> In-Reply-To: <20210810223238.979194-1-jingzhangos@google.com> From: Peter Feiner Date: Tue, 10 Aug 2021 15:44:48 -0700 Message-ID: Subject: Re: [PATCH] KVM: stats: Add VM dirty_pages stats for the number of dirty pages To: Jing Zhang Cc: KVM , KVMPPC , Paolo Bonzini , Peter Shier , Oliver Upton , David Matlack , Ben Gardon Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Aug 10, 2021 at 3:32 PM Jing Zhang wrote: > > Add a generic VM stats dirty_pages to record the number of dirty pages > reflected in dirty_bitmap at the moment. > > Original-by: Peter Feiner > Signed-off-by: Jing Zhang > --- > arch/powerpc/kvm/book3s_64_mmu_hv.c | 8 ++++++-- > arch/powerpc/kvm/book3s_64_mmu_radix.c | 1 + > arch/powerpc/kvm/book3s_hv_rm_mmu.c | 1 + > include/linux/kvm_host.h | 3 ++- > include/linux/kvm_types.h | 1 + > virt/kvm/kvm_main.c | 26 +++++++++++++++++++++++--- > 6 files changed, 34 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c > index c63e263312a4..e4aafa10efa1 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c > @@ -1122,8 +1122,10 @@ long kvmppc_hv_get_dirty_log_hpt(struct kvm *kvm, > * since we always put huge-page HPTEs in the rmap chain > * corresponding to their page base address. > */ > - if (npages) > + if (npages) { > set_dirty_bits(map, i, npages); > + kvm->stat.generic.dirty_pages += npages; > + } > ++rmapp; > } > preempt_enable(); > @@ -1178,8 +1180,10 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa, > gfn = gpa >> PAGE_SHIFT; > srcu_idx = srcu_read_lock(&kvm->srcu); > memslot = gfn_to_memslot(kvm, gfn); > - if (memslot && memslot->dirty_bitmap) > + if (memslot && memslot->dirty_bitmap) { > set_bit_le(gfn - memslot->base_gfn, memslot->dirty_bitmap); > + ++kvm->stat.generic.dirty_pages; > + } > srcu_read_unlock(&kvm->srcu, srcu_idx); > } > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c > index b5905ae4377c..3a6cb3854a44 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c > @@ -1150,6 +1150,7 @@ long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm, > j = i + 1; > if (npages) { > set_dirty_bits(map, i, npages); > + kvm->stat.generic.dirty_pages += npages; > j = i + npages; > } > } > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > index 632b2545072b..16806bc473fa 100644 > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > @@ -109,6 +109,7 @@ void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot, > npages = (psize + PAGE_SIZE - 1) / PAGE_SIZE; > gfn -= memslot->base_gfn; > set_dirty_bits_atomic(memslot->dirty_bitmap, gfn, npages); > + kvm->stat.generic.dirty_pages += npages; > } > EXPORT_SYMBOL_GPL(kvmppc_update_dirty_map); > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index f50bfcf225f0..1e8e66fb915b 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1421,7 +1421,8 @@ struct _kvm_stats_desc { > KVM_STATS_BASE_POW10, -9) > > #define KVM_GENERIC_VM_STATS() \ > - STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush) > + STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush), \ > + STATS_DESC_COUNTER(VM_GENERIC, dirty_pages) > > #define KVM_GENERIC_VCPU_STATS() \ > STATS_DESC_COUNTER(VCPU_GENERIC, halt_successful_poll), \ > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h > index ed6a985c5680..6c05df00aebf 100644 > --- a/include/linux/kvm_types.h > +++ b/include/linux/kvm_types.h > @@ -78,6 +78,7 @@ struct kvm_mmu_memory_cache { > > struct kvm_vm_stat_generic { > u64 remote_tlb_flush; > + u64 dirty_pages; > }; > > struct kvm_vcpu_stat_generic { > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index a438a7a3774a..93f0ca2ea326 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1228,6 +1228,19 @@ static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot) > return 0; > } > > +static inline unsigned long hweight_dirty_bitmap( > + struct kvm_memory_slot *memslot) > +{ > + unsigned long i; > + unsigned long count = 0; > + unsigned long n = kvm_dirty_bitmap_bytes(memslot); > + > + for (i = 0; i < n / sizeof(long); ++i) > + count += hweight_long(memslot->dirty_bitmap[i]); > + > + return count; > +} > + > /* > * Delete a memslot by decrementing the number of used slots and shifting all > * other entries in the array forward one spot. > @@ -1612,6 +1625,7 @@ static int kvm_delete_memslot(struct kvm *kvm, > if (r) > return r; > > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(old); > kvm_free_memslot(kvm, old); > return 0; > } > @@ -1733,8 +1747,10 @@ int __kvm_set_memory_region(struct kvm *kvm, > if (r) > goto out_bitmap; > > - if (old.dirty_bitmap && !new.dirty_bitmap) > + if (old.dirty_bitmap && !new.dirty_bitmap) { > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(&old); > kvm_destroy_dirty_bitmap(&old); > + } > return 0; > > out_bitmap: > @@ -1895,6 +1911,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) > offset = i * BITS_PER_LONG; > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > offset, mask); > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > } > KVM_MMU_UNLOCK(kvm); > } > @@ -2012,6 +2029,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, > flush = true; > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > offset, mask); > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > } > } > KVM_MMU_UNLOCK(kvm); > @@ -3062,11 +3080,13 @@ void mark_page_dirty_in_slot(struct kvm *kvm, > unsigned long rel_gfn = gfn - memslot->base_gfn; > u32 slot = (memslot->as_id << 16) | memslot->id; > > - if (kvm->dirty_ring_size) > + if (kvm->dirty_ring_size) { > kvm_dirty_ring_push(kvm_dirty_ring_get(kvm), > slot, rel_gfn); > - else > + } else { > set_bit_le(rel_gfn, memslot->dirty_bitmap); > + ++kvm->stat.generic.dirty_pages; Couple of problems here: - Calls to mark_page_dirty_in_slot aren't serialized by the mmu_lock, so these updates will race. - The page might already be dirty in the bitmap, so you're potentially double counting here You can fix both of these problems by changing set_bit_le to a test_and_set_bit_le (might not be the function name -- but you get the idea) and conditionally incrementing dirty_pages. > + } > } > } > EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot); > > base-commit: d0732b0f8884d9cc0eca0082bbaef043f3fef7fb > -- > 2.32.0.605.g8dce9f2422-goog > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Feiner Date: Tue, 10 Aug 2021 22:44:48 +0000 Subject: Re: [PATCH] KVM: stats: Add VM dirty_pages stats for the number of dirty pages Message-Id: List-Id: References: <20210810223238.979194-1-jingzhangos@google.com> In-Reply-To: <20210810223238.979194-1-jingzhangos@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jing Zhang Cc: KVM , KVMPPC , Paolo Bonzini , Peter Shier , Oliver Upton , David Matlack , Ben Gardon On Tue, Aug 10, 2021 at 3:32 PM Jing Zhang wrote: > > Add a generic VM stats dirty_pages to record the number of dirty pages > reflected in dirty_bitmap at the moment. > > Original-by: Peter Feiner > Signed-off-by: Jing Zhang > --- > arch/powerpc/kvm/book3s_64_mmu_hv.c | 8 ++++++-- > arch/powerpc/kvm/book3s_64_mmu_radix.c | 1 + > arch/powerpc/kvm/book3s_hv_rm_mmu.c | 1 + > include/linux/kvm_host.h | 3 ++- > include/linux/kvm_types.h | 1 + > virt/kvm/kvm_main.c | 26 +++++++++++++++++++++++--- > 6 files changed, 34 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c > index c63e263312a4..e4aafa10efa1 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c > @@ -1122,8 +1122,10 @@ long kvmppc_hv_get_dirty_log_hpt(struct kvm *kvm, > * since we always put huge-page HPTEs in the rmap chain > * corresponding to their page base address. > */ > - if (npages) > + if (npages) { > set_dirty_bits(map, i, npages); > + kvm->stat.generic.dirty_pages += npages; > + } > ++rmapp; > } > preempt_enable(); > @@ -1178,8 +1180,10 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa, > gfn = gpa >> PAGE_SHIFT; > srcu_idx = srcu_read_lock(&kvm->srcu); > memslot = gfn_to_memslot(kvm, gfn); > - if (memslot && memslot->dirty_bitmap) > + if (memslot && memslot->dirty_bitmap) { > set_bit_le(gfn - memslot->base_gfn, memslot->dirty_bitmap); > + ++kvm->stat.generic.dirty_pages; > + } > srcu_read_unlock(&kvm->srcu, srcu_idx); > } > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c > index b5905ae4377c..3a6cb3854a44 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c > @@ -1150,6 +1150,7 @@ long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm, > j = i + 1; > if (npages) { > set_dirty_bits(map, i, npages); > + kvm->stat.generic.dirty_pages += npages; > j = i + npages; > } > } > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > index 632b2545072b..16806bc473fa 100644 > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > @@ -109,6 +109,7 @@ void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot, > npages = (psize + PAGE_SIZE - 1) / PAGE_SIZE; > gfn -= memslot->base_gfn; > set_dirty_bits_atomic(memslot->dirty_bitmap, gfn, npages); > + kvm->stat.generic.dirty_pages += npages; > } > EXPORT_SYMBOL_GPL(kvmppc_update_dirty_map); > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index f50bfcf225f0..1e8e66fb915b 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1421,7 +1421,8 @@ struct _kvm_stats_desc { > KVM_STATS_BASE_POW10, -9) > > #define KVM_GENERIC_VM_STATS() \ > - STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush) > + STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush), \ > + STATS_DESC_COUNTER(VM_GENERIC, dirty_pages) > > #define KVM_GENERIC_VCPU_STATS() \ > STATS_DESC_COUNTER(VCPU_GENERIC, halt_successful_poll), \ > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h > index ed6a985c5680..6c05df00aebf 100644 > --- a/include/linux/kvm_types.h > +++ b/include/linux/kvm_types.h > @@ -78,6 +78,7 @@ struct kvm_mmu_memory_cache { > > struct kvm_vm_stat_generic { > u64 remote_tlb_flush; > + u64 dirty_pages; > }; > > struct kvm_vcpu_stat_generic { > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index a438a7a3774a..93f0ca2ea326 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1228,6 +1228,19 @@ static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot) > return 0; > } > > +static inline unsigned long hweight_dirty_bitmap( > + struct kvm_memory_slot *memslot) > +{ > + unsigned long i; > + unsigned long count = 0; > + unsigned long n = kvm_dirty_bitmap_bytes(memslot); > + > + for (i = 0; i < n / sizeof(long); ++i) > + count += hweight_long(memslot->dirty_bitmap[i]); > + > + return count; > +} > + > /* > * Delete a memslot by decrementing the number of used slots and shifting all > * other entries in the array forward one spot. > @@ -1612,6 +1625,7 @@ static int kvm_delete_memslot(struct kvm *kvm, > if (r) > return r; > > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(old); > kvm_free_memslot(kvm, old); > return 0; > } > @@ -1733,8 +1747,10 @@ int __kvm_set_memory_region(struct kvm *kvm, > if (r) > goto out_bitmap; > > - if (old.dirty_bitmap && !new.dirty_bitmap) > + if (old.dirty_bitmap && !new.dirty_bitmap) { > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(&old); > kvm_destroy_dirty_bitmap(&old); > + } > return 0; > > out_bitmap: > @@ -1895,6 +1911,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) > offset = i * BITS_PER_LONG; > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > offset, mask); > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > } > KVM_MMU_UNLOCK(kvm); > } > @@ -2012,6 +2029,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, > flush = true; > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > offset, mask); > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > } > } > KVM_MMU_UNLOCK(kvm); > @@ -3062,11 +3080,13 @@ void mark_page_dirty_in_slot(struct kvm *kvm, > unsigned long rel_gfn = gfn - memslot->base_gfn; > u32 slot = (memslot->as_id << 16) | memslot->id; > > - if (kvm->dirty_ring_size) > + if (kvm->dirty_ring_size) { > kvm_dirty_ring_push(kvm_dirty_ring_get(kvm), > slot, rel_gfn); > - else > + } else { > set_bit_le(rel_gfn, memslot->dirty_bitmap); > + ++kvm->stat.generic.dirty_pages; Couple of problems here: - Calls to mark_page_dirty_in_slot aren't serialized by the mmu_lock, so these updates will race. - The page might already be dirty in the bitmap, so you're potentially double counting here You can fix both of these problems by changing set_bit_le to a test_and_set_bit_le (might not be the function name -- but you get the idea) and conditionally incrementing dirty_pages. > + } > } > } > EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot); > > base-commit: d0732b0f8884d9cc0eca0082bbaef043f3fef7fb > -- > 2.32.0.605.g8dce9f2422-goog >