| Message ID | 20121119215959.499058001@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/20/2012 01:58 AM, Marcelo Tosatti wrote: > As requested by Glauber, do not update kvmclock area on vcpu->pcpu > migration, in case the host has stable TSC. > > This is to reduce cacheline bouncing. > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > > Index: vsyscall/arch/x86/kvm/x86.c > =================================================================== > --- vsyscall.orig/arch/x86/kvm/x86.c > +++ vsyscall/arch/x86/kvm/x86.c > @@ -2615,7 +2615,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu > kvm_x86_ops->write_tsc_offset(vcpu, offset); > vcpu->arch.tsc_catchup = 1; > } > - kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); > + /* > + * On a host with synchronized TSC, there is no need to update > + * kvmclock on vcpu->cpu migration > + */ > + if (!vcpu->kvm->arch.use_master_clock || vcpu->cpu == -1) > + kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); > if (vcpu->cpu != cpu) > kvm_migrate_timers(vcpu); > vcpu->cpu = cpu; Ok. Since you are only touching the one in kvm_arch_vcpu_load() and leaving the others untouched, it looks correct. Acked-by: Glauber Costa <glommer@parallels.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: vsyscall/arch/x86/kvm/x86.c =================================================================== --- vsyscall.orig/arch/x86/kvm/x86.c +++ vsyscall/arch/x86/kvm/x86.c @@ -2615,7 +2615,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu kvm_x86_ops->write_tsc_offset(vcpu, offset); vcpu->arch.tsc_catchup = 1; } - kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); + /* + * On a host with synchronized TSC, there is no need to update + * kvmclock on vcpu->cpu migration + */ + if (!vcpu->kvm->arch.use_master_clock || vcpu->cpu == -1) + kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); if (vcpu->cpu != cpu) kvm_migrate_timers(vcpu); vcpu->cpu = cpu;
As requested by Glauber, do not update kvmclock area on vcpu->pcpu migration, in case the host has stable TSC. This is to reduce cacheline bouncing. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html