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

Paolo Bonzini
2014-12-16T09:03:45Z

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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