From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH 3/4] KVM: MMU: track dirty page in speculative path properly Date: Fri, 16 Jul 2010 09:58:56 +0800 Message-ID: <4C3FBCE0.3030402@cn.fujitsu.com> References: <4C3C3518.7080505@cn.fujitsu.com> <4C3C35B7.50101@cn.fujitsu.com> <20100713220551.GB6370@amt.cnet> <4C3D11C6.4000101@cn.fujitsu.com> <20100714110926.GA26033@amt.cnet> <4C3DB942.3010709@cn.fujitsu.com> <20100714140626.GA28485@amt.cnet> <4C3EBC70.2030604@cn.fujitsu.com> <20100715164048.GA6980@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Avi Kivity , LKML , KVM list To: Marcelo Tosatti Return-path: In-Reply-To: <20100715164048.GA6980@amt.cnet> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Marcelo Tosatti wrote: >> It uses access bit to track both page accessed and page dirty, and it's rather cheap... > > Xiao, > > I don't understand it. What are you trying to achieve? > Marcelo, The issue which we try to fix in this patch is we mark the page dirty in speculative path, i'm not sure that after Lai's patch this bug is gone, if it's true, this patch is not needed anymore, otherwise the later patch is the cheaper way help us to fix this issue. In the later patch, we use pte.a to track whether the speculative mapping is accessed, if it's accessed, we mark the page dirty, just like tracking page-accessed.