Re: [kvm-devel] pinning, tsc and apic

[Avi Kivity <avi@qumranet.com>]

(catching up on unread email)

Chris Wright wrote:
> Is this with pinning?  We at least know we're losing small bits on
> migration.  From my measurements it's ~3000 (outliers are 10-20k).
>
> Also, what happens if you roll back to kvm-userspace 7f5c4d15ece5?
>
> I'm using this:
>
> diff -up arch/x86/kvm/svm.c~svm arch/x86/kvm/svm.c
> --- arch/x86/kvm/svm.c~svm	2008-04-16 19:49:44.000000000 -0700
> +++ arch/x86/kvm/svm.c	2008-05-14 23:44:18.000000000 -0700
> @@ -621,6 +621,13 @@ static void svm_free_vcpu(struct kvm_vcp
>  	kmem_cache_free(kvm_vcpu_cache, svm);
>  }
>  
> +static void svm_tsc_update(void *arg)
> +{
> +	struct vcpu_svm *svm = arg;
> +	rdtscll(svm->vcpu.arch.host_tsc);
> +
> +}
> +
>  static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  {
>  	struct vcpu_svm *svm = to_svm(vcpu);
> @@ -633,6 +640,9 @@ static void svm_vcpu_load(struct kvm_vcp
>  		 * Make sure that the guest sees a monotonically
>  		 * increasing TSC.
>  		 */
> +		if (vcpu->cpu != -1)
> +			smp_call_function_single(vcpu->cpu, svm_tsc_update,
> +						 svm, 0, 1);
>  		rdtscll(tsc_this);
>  		delta = vcpu->arch.host_tsc - tsc_this;
>  		svm->vmcb->control.tsc_offset += delta;
>
>   

Would like to apply, but want changelog and signoff.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.