linux-kernel - Re: [PATCH 6/6] KVM: MMU: trace pte prefetch

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Date:	Tue, 15 Jun 2010 15:09:21 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: Re: [PATCH 6/6] KVM: MMU: trace pte prefetch

On 06/15/2010 05:47 AM, Xiao Guangrong wrote:
> Trace pte prefetch to see what trouble we meet, if can help us to
> improve the prefetch
>
> Signed-off-by: Xiao Guangrong<xiaoguangrong@...fujitsu.com>
> ---
>   arch/x86/kvm/mmu.c         |   12 +++++++++++-
>   arch/x86/kvm/mmutrace.h    |   26 ++++++++++++++++++++++++++
>   arch/x86/kvm/paging_tmpl.h |    9 ++++++++-
>   3 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 941c86b..0aaa18d 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -91,6 +91,11 @@ module_param(oos_shadow, bool, 0644);
>
>   #define PTE_PREFETCH_NUM	16
>
> +#define PREFETCH_SUCCESS	0
> +#define PREFETCH_ERR_GFN2PFN	1
> +#define PREFETCH_ERR_ALLOC_MEM	2
> +#define PREFETCH_ERR_READ_GPTE	3
> +
>   #define PT_FIRST_AVAIL_BITS_SHIFT 9
>   #define PT64_SECOND_AVAIL_BITS_SHIFT 52
>
> @@ -2066,11 +2071,16 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
>   		pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn);
>   		if (is_error_pfn(pfn)) {
>   			kvm_release_pfn_clean(pfn);
> +			trace_pte_prefetch(true, PREFETCH_ERR_GFN2PFN);
>   			break;
>   		}
>    

What about virtual addresses and gptes?  They can be helpful too.

-- 
error compiling committee.c: too many arguments to function

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