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From: Avi Kivity <avi@redhat.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v3 11/11] KVM: MMU: improve write flooding detected
Date: Wed, 14 Sep 2011 12:59:01 +0300	[thread overview]
Message-ID: <4E707AE5.2030704@redhat.com> (raw)
In-Reply-To: <4E6FACBD.1020801@cn.fujitsu.com>

On 09/13/2011 10:19 PM, Xiao Guangrong wrote:
> >
> >  The spte may not be accessed, but other sptes in the same page can be accessed.  An example is the fixmap area for kmap_atomic(), there will be a lot of pte writes but other sptes will be accessed without going through soft-mmu at all.
>
> I think this kind of shadow pae is mostly the last page table(level=1), maybe
> we can skip the write-flooding for the last shadow page, because the last shadow
> page can become unsync and it can not let page table write-protected.

Yes.

>
> >  I think you have to read the parent_ptes->spte.accessed bits to be sure.
> >
>
> I guess the overload of this way is little high:
> - it needs to walk parent ptes for every shadow pages
> - we need to clear the parent_ptes->spte.accessed bit when the page is written, and
>    the tlb flush is needed.
> no?
>

Right.

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

  reply	other threads:[~2011-09-14  9:59 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-30  2:34 [PATCH v3 01/11] KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write Xiao Guangrong
2011-08-30  2:34 ` [PATCH v3 02/11] KVM: x86: tag the instructions which are used to write page table Xiao Guangrong
2011-08-30  2:35 ` [PATCH v3 03/11] KVM: x86: retry non-page-table writing instruction Xiao Guangrong
2011-09-13 10:47   ` Avi Kivity
2011-09-13 18:24     ` Xiao Guangrong
2011-09-14  9:53       ` Avi Kivity
2011-09-14 10:19         ` Xiao Guangrong
2011-09-15  4:56           ` Xiao Guangrong
2011-08-30  2:35 ` [PATCH v3 04/11] KVM: x86: cleanup port-in/port-out emulated Xiao Guangrong
2011-08-30  2:35 ` [PATCH v3 05/11] KVM: MMU: do not mark accessed bit on pte write path Xiao Guangrong
2011-09-13 10:53   ` Avi Kivity
2011-09-13 18:29     ` Xiao Guangrong
2011-09-14  9:55       ` Avi Kivity
2011-09-15 13:11         ` Marcelo Tosatti
2011-08-30  2:36 ` [PATCH v3 06/11] KVM: MMU: cleanup FNAME(invlpg) Xiao Guangrong
2011-09-13 11:00   ` Avi Kivity
2011-09-13 18:31     ` Xiao Guangrong
2011-09-14  9:57       ` Avi Kivity
2011-08-30  2:36 ` [PATCH v3 07/11] KVM: MMU: fast prefetch spte on invlpg path Xiao Guangrong
2011-08-30  2:37 ` [PATCH v3 08/11] KVM: MMU: remove unnecessary kvm_mmu_free_some_pages Xiao Guangrong
2011-08-30  2:37 ` [PATCH v3 09/11] KVM: MMU: split kvm_mmu_pte_write function Xiao Guangrong
2011-08-30  2:37 ` [PATCH v3 10/11] KVM: MMU: fix detecting misaligned accessed Xiao Guangrong
2011-08-30  2:38 ` [PATCH v3 11/11] KVM: MMU: improve write flooding detected Xiao Guangrong
2011-09-13 11:07   ` Avi Kivity
2011-09-13 19:19     ` Xiao Guangrong
2011-09-14  9:59       ` Avi Kivity [this message]
2011-09-13  9:51 ` [PATCH v3 01/11] KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write Avi Kivity
2011-09-13 10:24   ` Xiao Guangrong
2011-09-13 10:50     ` Avi Kivity
2011-09-13 19:31       ` Xiao Guangrong

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