On Tue, Jun 12, 2012 at 07:27:48PM -0300, Marcelo Tosatti wrote: > 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@xxxxxxxxxx> > > --- > > 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/ Do we have to measure every single thing? Sometimes it's obvious: vapic is slow path, isn't it? -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html