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 6BB5A8D0040 for ; Mon, 28 Mar 2011 11:01:34 -0400 (EDT) Received: by mail-ww0-f54.google.com with SMTP id 20so3833020wwd.11 for ; Mon, 28 Mar 2011 08:01:02 -0700 (PDT) Message-ID: <4D90A236.9030200@ravellosystems.com> Date: Mon, 28 Mar 2011 16:59:02 +0200 From: Izik Eidus MIME-Version: 1.0 Subject: Re: [PATCH 0/2] ksm: take dirty bit as reference to avoid volatile pages References: <201103282214.19345.nai.xia@gmail.com> In-Reply-To: <201103282214.19345.nai.xia@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: nai.xia@gmail.com Cc: linux-kernel , Andrew Morton , Hugh Dickins , Johannes Weiner , Chris Wright , Andrea Arcangeli , Rik van Riel , linux-mm On 03/28/2011 04:14 PM, Nai Xia wrote: > Currently, ksm uses page checksum to detect volatile pages. Izik Eidus > suggested that we could use pte dirty bit to optimize. This patch series > adds this new logic. > Hi, One small note: When kvm will use ksm on intel cpu with extended page tables support, the cpu won`t track dirty bit, therefore the calc_hash() logic should be used in such cases (untill intel will fadd this support in their cpus)... Moreover I think that even though that AMD nested page tables does update dirty bit, you still need to sync it with the host page table using mmu notifiers ? (Not that on regular application use case of ksm any of this should be an issue) -- 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