From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758687Ab0GPCDA (ORCPT ); Thu, 15 Jul 2010 22:03:00 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:65290 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758649Ab0GPCC6 (ORCPT ); Thu, 15 Jul 2010 22:02:58 -0400 Message-ID: <4C3FBCE0.3030402@cn.fujitsu.com> Date: Fri, 16 Jul 2010 09:58:56 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Marcelo Tosatti CC: Avi Kivity , LKML , KVM list Subject: Re: [PATCH 3/4] KVM: MMU: track dirty page in speculative path properly 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> In-Reply-To: <20100715164048.GA6980@amt.cnet> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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.