From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id D545D6B003D for ; Mon, 30 Mar 2009 15:14:14 -0400 (EDT) Message-ID: <49D11674.9040205@goop.org> Date: Mon, 30 Mar 2009 11:59:00 -0700 From: Jeremy Fitzhardinge MIME-Version: 1.0 Subject: Re: [patch 0/6] Guest page hinting version 7. References: <20090327150905.819861420@de.ibm.com> <1238195024.8286.562.camel@nimitz> <20090329161253.3faffdeb@skybase> <1238428495.8286.638.camel@nimitz> <49D11184.3060002@goop.org> <49D11287.4030307@redhat.com> In-Reply-To: <49D11287.4030307@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: Dave Hansen , Martin Schwidefsky , akpm@osdl.org, nickpiggin@yahoo.com.au, frankeh@watson.ibm.com, virtualization@lists.osdl.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, hugh@veritas.com List-ID: Rik van Riel wrote: > Jeremy Fitzhardinge wrote: > >> That said, people have been looking at tracking block IO to work out >> when it might be useful to try and share pages between guests under Xen. > > Tracking block IO seems like a bass-ackwards way to figure > out what the contents of a memory page are. Well, they're research projects, so nobody said that they're necessarily useful results ;). I think the rationale is that, in general, there aren't all that many sharable pages, and asize from zero-pages, the bulk of them are the result of IO. Since its much simpler to compare device+block references than doing page content matching, it is worth looking at the IO stream to work out what your candidates are. > The KVM KSM code has a simpler, yet still efficient, way of > figuring out which memory pages can be shared. How's that? Does it do page content comparison? J -- 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/ . Don't email: email@kvack.org