From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 5D45F6B004D for ; Thu, 9 Jul 2009 17:08:27 -0400 (EDT) Message-ID: <4A5660CB.5080607@redhat.com> Date: Thu, 09 Jul 2009 17:27:39 -0400 From: Rik van Riel MIME-Version: 1.0 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: owner-linux-mm@kvack.org 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 List-ID: 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, 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