| Message ID | 1564572438-15518-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] KVM: Don't need to wakeup vCPU twice afer timer fire | expand |
On 31/07/19 13:27, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > kvm_set_pending_timer() will take care to wake up the sleeping vCPU which > has pending timer, don't need to check this in apic_timer_expired() again. No, it doesn't. kvm_make_request never kicks the vCPU. Paolo > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > arch/x86/kvm/lapic.c | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 0aa1586..685d17c 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1548,7 +1548,6 @@ static void kvm_apic_inject_pending_timer_irqs(struct kvm_lapic *apic) > static void apic_timer_expired(struct kvm_lapic *apic) > { > struct kvm_vcpu *vcpu = apic->vcpu; > - struct swait_queue_head *q = &vcpu->wq; > struct kvm_timer *ktimer = &apic->lapic_timer; > > if (atomic_read(&apic->lapic_timer.pending)) > @@ -1566,13 +1565,6 @@ static void apic_timer_expired(struct kvm_lapic *apic) > > atomic_inc(&apic->lapic_timer.pending); > kvm_set_pending_timer(vcpu); > - > - /* > - * For x86, the atomic_inc() is serialized, thus > - * using swait_active() is safe. > - */ > - if (swait_active(q)) > - swake_up_one(q); > } > > static void start_sw_tscdeadline(struct kvm_lapic *apic) >
Paolo Bonzini <pbonzini@redhat.com> writes: > On 31/07/19 13:27, Wanpeng Li wrote: >> From: Wanpeng Li <wanpengli@tencent.com> >> >> kvm_set_pending_timer() will take care to wake up the sleeping vCPU which >> has pending timer, don't need to check this in apic_timer_expired() again. > > No, it doesn't. kvm_make_request never kicks the vCPU. > Hm, but kvm_set_pending_timer() currently looks like: void kvm_set_pending_timer(struct kvm_vcpu *vcpu) { kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); kvm_vcpu_kick(vcpu); }
On 31/07/19 15:14, Vitaly Kuznetsov wrote: > Paolo Bonzini <pbonzini@redhat.com> writes: > >> On 31/07/19 13:27, Wanpeng Li wrote: >>> From: Wanpeng Li <wanpengli@tencent.com> >>> >>> kvm_set_pending_timer() will take care to wake up the sleeping vCPU which >>> has pending timer, don't need to check this in apic_timer_expired() again. >> >> No, it doesn't. kvm_make_request never kicks the vCPU. >> > > Hm, but kvm_set_pending_timer() currently looks like: > > void kvm_set_pending_timer(struct kvm_vcpu *vcpu) > { > kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); > kvm_vcpu_kick(vcpu); > } Doing "git fetch" could have helped indeed. Paolo
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 0aa1586..685d17c 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1548,7 +1548,6 @@ static void kvm_apic_inject_pending_timer_irqs(struct kvm_lapic *apic) static void apic_timer_expired(struct kvm_lapic *apic) { struct kvm_vcpu *vcpu = apic->vcpu; - struct swait_queue_head *q = &vcpu->wq; struct kvm_timer *ktimer = &apic->lapic_timer; if (atomic_read(&apic->lapic_timer.pending)) @@ -1566,13 +1565,6 @@ static void apic_timer_expired(struct kvm_lapic *apic) atomic_inc(&apic->lapic_timer.pending); kvm_set_pending_timer(vcpu); - - /* - * For x86, the atomic_inc() is serialized, thus - * using swait_active() is safe. - */ - if (swait_active(q)) - swake_up_one(q); } static void start_sw_tscdeadline(struct kvm_lapic *apic)