From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 5/6] kvm, x86: use ro page and don't copy shared page Date: Sun, 18 Jul 2010 18:31:18 +0300 Message-ID: <4C431E46.3010001@redhat.com> References: <4C3FC033.3000605@cn.fujitsu.com> <20100716071936.GE17894@redhat.com> <20100716232612.GB8946@amt.cnet> <20100717043124.GA24480@redhat.com> <4C431A43.5010808@redhat.com> <20100718152321.GA20355@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , Lai Jiangshan , LKML , kvm@vger.kernel.org, Nick Piggin To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53308 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756442Ab0GRPbZ (ORCPT ); Sun, 18 Jul 2010 11:31:25 -0400 In-Reply-To: <20100718152321.GA20355@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/18/2010 06:23 PM, Gleb Natapov wrote: > On Sun, Jul 18, 2010 at 06:14:11PM +0300, Avi Kivity wrote: > >> On 07/17/2010 07:31 AM, Gleb Natapov wrote: >> >>>>> Currently pages allocated for guest memory are required to be RW, so after your series >>>>> behaviour will remain exactly the same as before. >>>>> >>>> Except KSM pages. >>>> >>>> >>> KSM page will be COWed by __get_user_pages_fast(addr, 1, 1, page) in >>> get_user_page_and_protection() just like it COWed now, no? >>> >> Well, we don't want to COW it on write faults. >> I meant read faults here. >> The optimal behaviour is: >> >> - write faults: COW and instantiate a writeable spte >> > So do we or don't we want to COW on write faults? > We do (no choice). -- error compiling committee.c: too many arguments to function