From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 3/4] KVM MMU: allow shadow page become unsync at creating
 time
Date: Fri, 30 Apr 2010 12:54:00 +0300
Message-ID: <4BDAA8B8.9030103@redhat.com>
References: <4BDA9C37.9070602@cn.fujitsu.com> <4BDA9C86.8080204@cn.fujitsu.com> <4BDA9CD0.6070501@cn.fujitsu.com>
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Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	KVM list <kvm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
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On 04/30/2010 12:03 PM, Xiao Guangrong wrote:
> Allow new shadow page become unsync when is created, then we no need
> write-protect the 'sp->gfn', this idea is from Avi:
>
> |Another interesting case is to create new shadow pages in the unsync
> |state. That can help when the guest starts a short lived process: we
> |can avoid write protecting its pagetables completely
>
>    

Any idea how this improves performance?  A kernel build has a lot of 
short lived processes, might see an improvement there.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.