kindly ping, On Fri, 14 Dec 2018 at 15:24, Wanpeng Li <kernellwp@xxxxxxxxx> wrote: > > ping, > On Thu, 6 Dec 2018 at 15:58, Wanpeng Li <kernellwp@xxxxxxxxx> wrote: > > > > From: Wanpeng Li <wanpengli@xxxxxxxxxxx> > > > > Last year guys from huawei reported that the call of memory_global_dirty_log_start/stop() > > takes 13s for 4T memory and cause guest freeze too long which increases the unacceptable > > migration downtime. [1] [2] > > > > Guangrong pointed out: > > > > | collapsible_sptes zaps 4k mappings to make memory-read happy, it is not > > | required by the semanteme of KVM_SET_USER_MEMORY_REGION and it is not > > | urgent for vCPU's running, it could be done in a separate thread and use > > | lock-break technology. > > > > [1] https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg05249.html > > [2] https://www.mail-archive.com/qemu-devel@xxxxxxxxxx/msg449994.html > > > > Several TB memory guest is common now after NVDIMM is deployed in cloud environment. > > This patch utilizes worker thread to zap collapsible sptes in order to lazy collapse > > small sptes into large sptes during roll-back after live migration fails. > > > > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> > > Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx> > > --- > > arch/x86/include/asm/kvm_host.h | 3 +++ > > arch/x86/kvm/mmu.c | 37 ++++++++++++++++++++++++++++++++----- > > arch/x86/kvm/x86.c | 4 ++++ > > 3 files changed, 39 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index fbda5a9..dde32f9 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -892,6 +892,8 @@ struct kvm_arch { > > u64 master_cycle_now; > > struct delayed_work kvmclock_update_work; > > struct delayed_work kvmclock_sync_work; > > + struct delayed_work kvm_mmu_zap_collapsible_sptes_work; > > + bool zap_in_progress; > > > > struct kvm_xen_hvm_config xen_hvm_config; > > > > @@ -1247,6 +1249,7 @@ void kvm_mmu_zap_all(struct kvm *kvm); > > void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, struct kvm_memslots *slots); > > unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm); > > void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages); > > +void zap_collapsible_sptes_fn(struct work_struct *work); > > > > int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3); > > bool pdptrs_changed(struct kvm_vcpu *vcpu); > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > > index 7c03c0f..fe87dd3 100644 > > --- a/arch/x86/kvm/mmu.c > > +++ b/arch/x86/kvm/mmu.c > > @@ -5679,14 +5679,41 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, > > return need_tlb_flush; > > } > > > > +void zap_collapsible_sptes_fn(struct work_struct *work) > > +{ > > + struct kvm_memory_slot *memslot; > > + struct kvm_memslots *slots; > > + struct delayed_work *dwork = to_delayed_work(work); > > + struct kvm_arch *ka = container_of(dwork, struct kvm_arch, > > + kvm_mmu_zap_collapsible_sptes_work); > > + struct kvm *kvm = container_of(ka, struct kvm, arch); > > + int i; > > + > > + mutex_lock(&kvm->slots_lock); > > + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { > > + spin_lock(&kvm->mmu_lock); > > + slots = __kvm_memslots(kvm, i); > > + kvm_for_each_memslot(memslot, slots) { > > + slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot, > > + kvm_mmu_zap_collapsible_spte, true); > > + if (need_resched() || spin_needbreak(&kvm->mmu_lock)) > > + cond_resched_lock(&kvm->mmu_lock); > > + } > > + spin_unlock(&kvm->mmu_lock); > > + } > > + kvm->arch.zap_in_progress = false; > > + mutex_unlock(&kvm->slots_lock); > > +} > > + > > +#define KVM_MMU_ZAP_DELAYED (60 * HZ) > > void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, > > const struct kvm_memory_slot *memslot) > > { > > - /* FIXME: const-ify all uses of struct kvm_memory_slot. */ > > - spin_lock(&kvm->mmu_lock); > > - slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot, > > - kvm_mmu_zap_collapsible_spte, true); > > - spin_unlock(&kvm->mmu_lock); > > + if (!kvm->arch.zap_in_progress) { > > + kvm->arch.zap_in_progress = true; > > + schedule_delayed_work(&kvm->arch.kvm_mmu_zap_collapsible_sptes_work, > > + KVM_MMU_ZAP_DELAYED); > > + } > > } > > > > void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index d029377..c2af289 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -9019,6 +9019,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > > > > INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn); > > INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn); > > + INIT_DELAYED_WORK(&kvm->arch.kvm_mmu_zap_collapsible_sptes_work, > > + zap_collapsible_sptes_fn); > > + kvm->arch.zap_in_progress = false; > > > > kvm_hv_init_vm(kvm); > > kvm_page_track_init(kvm); > > @@ -9064,6 +9067,7 @@ void kvm_arch_sync_events(struct kvm *kvm) > > { > > cancel_delayed_work_sync(&kvm->arch.kvmclock_sync_work); > > cancel_delayed_work_sync(&kvm->arch.kvmclock_update_work); > > + cancel_delayed_work_sync(&kvm->arch.kvm_mmu_zap_collapsible_sptes_work); > > kvm_free_pit(kvm); > > } > > > > -- > > 2.7.4 > >
