On 16/04/20 17:09, Marc Zyngier wrote: > On Wed, 15 Apr 2020 18:13:56 +0200 > Paolo Bonzini <[email protected]> wrote: > >> On 13/04/20 14:20, Keqian Zhu wrote: >>> There is already support of enabling dirty log graually in small chunks >>> for x86 in commit 3c9bd4006bfc ("KVM: x86: enable dirty log gradually in >>> small chunks"). This adds support for arm64. >>> >>> x86 still writes protect all huge pages when DIRTY_LOG_INITIALLY_ALL_SET >>> is eanbled. However, for arm64, both huge pages and normal pages can be >>> write protected gradually by userspace. >>> >>> Under the Huawei Kunpeng 920 2.6GHz platform, I did some tests on 128G >>> Linux VMs with different page size. The memory pressure is 127G in each >>> case. The time taken of memory_global_dirty_log_start in QEMU is listed >>> below: >>> >>> Page Size Before After Optimization >>> 4K 650ms 1.8ms >>> 2M 4ms 1.8ms >>> 1G 2ms 1.8ms >>> >>> Besides the time reduction, the biggest income is that we will minimize >>> the performance side effect (because of dissloving huge pages and marking >>> memslots dirty) on guest after enabling dirty log. >>> >>> Signed-off-by: Keqian Zhu <[email protected]> >>> --- >>> Documentation/virt/kvm/api.rst | 2 +- >>> arch/arm64/include/asm/kvm_host.h | 3 +++ >>> virt/kvm/arm/mmu.c | 12 ++++++++++-- >>> 3 files changed, 14 insertions(+), 3 deletions(-) >>> >>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst >>> index efbbe570aa9b..0017f63fa44f 100644 >>> --- a/Documentation/virt/kvm/api.rst >>> +++ b/Documentation/virt/kvm/api.rst >>> @@ -5777,7 +5777,7 @@ will be initialized to 1 when created. This also >>> improves performance because >>> dirty logging can be enabled gradually in small chunks on the first call >>> to KVM_CLEAR_DIRTY_LOG. KVM_DIRTY_LOG_INITIALLY_SET depends on >>> KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (it is also only available on >>> -x86 for now). >>> +x86 and arm64 for now). >>> >>> KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name >>> KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make >>> diff --git a/arch/arm64/include/asm/kvm_host.h >>> b/arch/arm64/include/asm/kvm_host.h >>> index 32c8a675e5a4..a723f84fab83 100644 >>> --- a/arch/arm64/include/asm/kvm_host.h >>> +++ b/arch/arm64/include/asm/kvm_host.h >>> @@ -46,6 +46,9 @@ >>> #define KVM_REQ_RECORD_STEAL KVM_ARCH_REQ(3) >>> #define KVM_REQ_RELOAD_GICv4 KVM_ARCH_REQ(4) >>> >>> +#define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | >>> \ >>> + KVM_DIRTY_LOG_INITIALLY_SET) >>> + >>> DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use); >>> >>> extern unsigned int kvm_sve_max_vl; >>> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c >>> index e3b9ee268823..1077f653a611 100644 >>> --- a/virt/kvm/arm/mmu.c >>> +++ b/virt/kvm/arm/mmu.c >>> @@ -2265,8 +2265,16 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, >>> * allocated dirty_bitmap[], dirty pages will be be tracked while the >>> * memory slot is write protected. >>> */ >>> - if (change != KVM_MR_DELETE && mem->flags & KVM_MEM_LOG_DIRTY_PAGES) >>> - kvm_mmu_wp_memory_region(kvm, mem->slot); >>> + if (change != KVM_MR_DELETE && mem->flags & KVM_MEM_LOG_DIRTY_PAGES) { >>> + /* >>> + * If we're with initial-all-set, we don't need to write >>> + * protect any pages because they're all reported as dirty. >>> + * Huge pages and normal pages will be write protect gradually. >>> + */ >>> + if (!kvm_dirty_log_manual_protect_and_init_set(kvm)) { >>> + kvm_mmu_wp_memory_region(kvm, mem->slot); >>> + } >>> + } >>> } >>> >>> int kvm_arch_prepare_memory_region(struct kvm *kvm, >>> >> >> Marc, what is the status of this patch? > > I just had a look at it. Is there any urgency for merging it?
No, I thought I was still replying to the v1. Paolo _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
