From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 117AA900185 for ; Wed, 22 Jun 2011 07:31:21 -0400 (EDT) Message-ID: <4E01D27F.8080304@redhat.com> Date: Wed, 22 Jun 2011 14:31:11 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [PATCH] mmu_notifier, kvm: Introduce dirty bit tracking in spte and mmu notifier to help KSM dirty bit tracking References: <201106212055.25400.nai.xia@gmail.com> <201106212132.39311.nai.xia@gmail.com> <4E01C752.10405@redhat.com> <4E01CC77.10607@ravellosystems.com> <4E01CDAD.3070202@redhat.com> <4E01CFD2.6000404@ravellosystems.com> <4E01D0E3.9080508@redhat.com> <4E01D1C8.2050707@redhat.com> In-Reply-To: <4E01D1C8.2050707@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Izik Eidus Cc: nai.xia@gmail.com, Andrew Morton , Andrea Arcangeli , Hugh Dickins , Chris Wright , Rik van Riel , linux-mm , Johannes Weiner , linux-kernel , kvm On 06/22/2011 02:28 PM, Avi Kivity wrote: > > Actually, this is dangerous. If we use the dirty bit for other > things, we will get data corruption. > > For example we might want to map clean host pages as writeable-clean > in the spte on a read fault so that we don't get a page fault when > they get eventually written. > Another example - we can use the dirty bit for dirty page loggging. So I think we can get away with a conditional tlb flush - only flush if the page was dirty. That should be rare after the first pass, at least with small pages. -- error compiling committee.c: too many arguments to function -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org