Re: [patch 3/3] KVM: x86: add tracepoint to wait_lapic_expire

[Paolo Bonzini <pbonzini@redhat.com>]

On 15/12/2014 23:06, Marcelo Tosatti wrote:
> Add tracepoint to wait_lapic_expire.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> Index: kvm/arch/x86/kvm/lapic.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/lapic.c
> +++ kvm/arch/x86/kvm/lapic.c
> @@ -1121,6 +1121,7 @@ void wait_lapic_expire(struct kvm_vcpu *
>  {
>  	struct kvm_lapic *apic = vcpu->arch.apic;
>  	u64 guest_tsc, tsc_deadline;
> +	unsigned int total_delay = 0;
>  
>  	if (!kvm_vcpu_has_lapic(vcpu))
>  		return;
> @@ -1138,9 +1139,13 @@ void wait_lapic_expire(struct kvm_vcpu *
>  	while (guest_tsc < tsc_deadline) {
>  		int delay = min(tsc_deadline - guest_tsc, 1000ULL);
>  
> +		total_delay += delay;
> +
>  		__delay(delay);
>  		guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu, native_read_tsc());
>  	}
> +
> +	trace_kvm_wait_lapic_expire(vcpu->vcpu_id, total_delay);

Let's add guest_tsc - tsc_deadline to the tracepoint.  This should
simplify the tuning of the parameter.

Paolo


>  }
>  
>  static void start_apic_timer(struct kvm_lapic *apic)
> Index: kvm/arch/x86/kvm/trace.h
> ===================================================================
> --- kvm.orig/arch/x86/kvm/trace.h
> +++ kvm/arch/x86/kvm/trace.h
> @@ -914,6 +914,25 @@ TRACE_EVENT(kvm_pvclock_update,
>  		  __entry->flags)
>  );
>  
> +TRACE_EVENT(kvm_wait_lapic_expire,
> +	TP_PROTO(unsigned int vcpu_id, unsigned int total_delay),
> +	TP_ARGS(vcpu_id, total_delay),
> +
> +	TP_STRUCT__entry(
> +		__field(	unsigned int,	vcpu_id			)
> +		__field(	unsigned int,	total_delay		)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->vcpu_id	   = vcpu_id;
> +		__entry->total_delay	   = total_delay;
> +	),
> +
> +	TP_printk("vcpu %u: total_delay %u",
> +		  __entry->vcpu_id,
> +		  __entry->total_delay)
> +);
> +
>  #endif /* _TRACE_KVM_H */
>  
>  #undef TRACE_INCLUDE_PATH
> 
> 
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