linux-kernel - Re: [PATCH v2 1/7] KVM: fix tracing kvm_try_async_get

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Message-ID: <20101101130944.GF31722@redhat.com>
Date:	Mon, 1 Nov 2010 15:09:44 +0200
From:	Gleb Natapov <gleb@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Cc:	Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH v2 1/7] KVM: fix tracing kvm_try_async_get_page

On Mon, Nov 01, 2010 at 04:58:43PM +0800, Xiao Guangrong wrote:
> Tracing 'async' and *pfn is useless, since 'async' is always true,
> and '*pfn' is always "fault_pfn'
> 
> We can trace 'gva' and 'gfn' instead, it can help us to see the
> life-cycle of an async_pf
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Acked-by: Gleb Natapov <gleb@...hat.com>

> ---
>  arch/x86/kvm/mmu.c         |    2 +-
>  include/trace/events/kvm.h |   12 +++++++-----
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 39cc0c6..5275c50 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2627,7 +2627,7 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool no_apf, gfn_t gfn,
>  	put_page(pfn_to_page(*pfn));
>  
>  	if (!no_apf && can_do_async_pf(vcpu)) {
> -		trace_kvm_try_async_get_page(async, *pfn);
> +		trace_kvm_try_async_get_page(gva, gfn);
>  		if (kvm_find_async_pf_gfn(vcpu, gfn)) {
>  			trace_kvm_async_pf_doublefault(gva, gfn);
>  			kvm_make_request(KVM_REQ_APF_HALT, vcpu);
> diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
> index 9c2cc6a..30063c6 100644
> --- a/include/trace/events/kvm.h
> +++ b/include/trace/events/kvm.h
> @@ -188,18 +188,20 @@ TRACE_EVENT(kvm_age_page,
>  #ifdef CONFIG_KVM_ASYNC_PF
>  TRACE_EVENT(
>  	kvm_try_async_get_page,
> -	TP_PROTO(bool async, u64 pfn),
> -	TP_ARGS(async, pfn),
> +	TP_PROTO(u64 gva, u64 gfn),
> +	TP_ARGS(gva, gfn),
>  
>  	TP_STRUCT__entry(
> -		__field(__u64, pfn)
> +		__field(u64, gva)
> +		__field(u64, gfn)
>  		),
>  
>  	TP_fast_assign(
> -		__entry->pfn = (!async) ? pfn : (u64)-1;
> +		__entry->gva = gva;
> +		__entry->gfn = gfn;
>  		),
>  
> -	TP_printk("pfn %#llx", __entry->pfn)
> +	TP_printk("gva = %#llx, gfn = %#llx", __entry->gva, __entry->gfn)
>  );
>  
>  TRACE_EVENT(
> -- 
> 1.7.0.4

--
			Gleb.
--
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