Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755825AbZGIV2V (ORCPT ); Thu, 9 Jul 2009 17:28:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755283AbZGIV2N (ORCPT ); Thu, 9 Jul 2009 17:28:13 -0400 Received: from mx2.redhat.com ([66.187.237.31]:55711 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755177AbZGIV2N (ORCPT ); Thu, 9 Jul 2009 17:28:13 -0400 Message-ID: <4A5660CB.5080607@redhat.com> Date: Thu, 09 Jul 2009 17:27:39 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 2.0.0.17 (X11/20080915) MIME-Version: 1.0 To: Dan Magenheimer CC: Anthony Liguori , linux-kernel@vger.kernel.org, npiggin@suse.de, akpm@osdl.org, jeremy@goop.org, xen-devel@lists.xensource.com, tmem-devel@oss.oracle.com, alan@lxorguk.ukuu.org.uk, linux-mm@kvack.org, kurt.hackel@oracle.com, Rusty Russell , dave.mccracken@oracle.com, Marcelo Tosatti , sunil.mushran@oracle.com, Avi Kivity , Schwidefsky , chris.mason@oracle.com, Balbir Singh Subject: Re: [RFC PATCH 0/4] (Take 2): transcendent memory ("tmem") for Linux References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1120 Lines: 31 Dan Magenheimer wrote: > I'm not saying either one is bad or good -- and I'm sure > each can be adapted to approximately deliver the value > of the other -- they are just approaching the same problem > from different perspectives. Indeed. Tmem and auto-ballooning have a simple mechanism, but the policy required to make it work right could well be too complex to ever get right. CMM2 has a more complex mechanism, but the policy is absolutely trivial. CMM2 and auto-ballooning seem to give about similar performance gains on zSystem. I suspect that for Xen and KVM, we'll want to choose for the approach that has the simpler policy, because relying on different versions of different operating systems to all get the policy of auto-ballooning or tmem right is likely to result in bad interactions between guests and other intractable issues. -- All rights reversed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/