Messages in this thread | | | Date | Tue, 12 Jun 2012 19:27:48 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCHv6 6/8] kvm: only sync when attention bits set |
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On Sun, Jun 03, 2012 at 10:28:29AM +0300, Michael S. Tsirkin wrote: > Commit eb0dc6d0368072236dcd086d7fdc17fd3c4574d4 introduced apic > attention bitmask but kvm still syncs lapic unconditionally. > As that commit suggested and in anticipation of adding more attention > bits, only sync lapic if(apic_attention). > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > --- > arch/x86/kvm/x86.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index be6d549..2f70861 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5388,7 +5388,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > if (unlikely(vcpu->arch.tsc_always_catchup)) > kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); > > - kvm_lapic_sync_from_vapic(vcpu); > + if (unlikely(vcpu->arch.apic_attention)) > + kvm_lapic_sync_from_vapic(vcpu);
void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu) { u32 data; void *vapic;
if (!test_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention)) return;
Please use unlikely more carefully, when a gain is measureable: http://lwn.net/Articles/420019/
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