Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753057AbZFCBCt (ORCPT ); Tue, 2 Jun 2009 21:02:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751392AbZFCBCm (ORCPT ); Tue, 2 Jun 2009 21:02:42 -0400 Received: from acsinet11.oracle.com ([141.146.126.233]:51457 "EHLO acsinet11.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbZFCBCl (ORCPT ); Tue, 2 Jun 2009 21:02:41 -0400 Date: Tue, 2 Jun 2009 18:00:00 -0700 From: Joel Becker To: Ingo Molnar Cc: Steven Rostedt , George Dunlap , David Miller , "jeremy@goop.org" , Dan Magenheimer , "avi@redhat.com" , "xen-devel@lists.xensource.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Keir Fraser , "torvalds@linux-foundation.org" , "gregkh@suse.de" , "kurt.hackel@oracle.com" , Ian Pratt , "xen-users@lists.xensource.com" , ksrinivasan , "EAnderson@novell.com" , "wimcoekaerts@wimmekes.net" , Stephen Spector , "jens.axboe@oracle.com" , "npiggin@suse.de" Subject: Re: Merge Xen (the hypervisor) into Linux Message-ID: <20090603010000.GE31976@mail.oracle.com> Mail-Followup-To: Ingo Molnar , Steven Rostedt , George Dunlap , David Miller , "jeremy@goop.org" , Dan Magenheimer , "avi@redhat.com" , "xen-devel@lists.xensource.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Keir Fraser , "torvalds@linux-foundation.org" , "gregkh@suse.de" , "kurt.hackel@oracle.com" , Ian Pratt , "xen-users@lists.xensource.com" , ksrinivasan , "EAnderson@novell.com" , "wimcoekaerts@wimmekes.net" , Stephen Spector , "jens.axboe@oracle.com" , "npiggin@suse.de" References: <162f4c90-6431-4a2a-b337-6d7451d7b11e@default> <20090528001350.GD26820@elte.hu> <4A1F302E.8030501@goop.org> <20090528.210559.137121893.davem@davemloft.net> <4A1FCE8E.2060604@eu.citrix.com> <20090602224051.GB32428@goodmis.org> <20090602232843.GA6577@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090602232843.GA6577@elte.hu> X-Burt-Line: Trees are cool. X-Red-Smith: Ninety feet between bases is perhaps as close as man has ever come to perfection. User-Agent: Mutt/1.5.18 (2008-05-17) X-Source-IP: acsmt357.oracle.com [141.146.40.157] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A010204.4A25CB40.00CA:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3078 Lines: 66 [ Speaking as me, no regard to $EMPLOYER ] On Wed, Jun 03, 2009 at 01:28:43AM +0200, Ingo Molnar wrote: > A lot of Xen legacies could be dropped: the crazy ring1 hack on > 32-bit, the various wide interfaces to make pure-software > virtualization limp along. All major CPUs shipped with hardware > virtualization support in the past 2-3 years, so the availability of > VMX and SVM can be taken for granted for such a project. The biggest reason I personally want Xen to be in mainline is PVM. Dropping PVM is, to me, pretty much saying "let's merge Xen without taking the useful parts." I have only two large machines I control. They're too big to run as single hosts - it's a waste - but I can leverage cluster testing by virtualizing them. The first machine has HVM support. The early kind. It's about 2 years old. It's so dreadfully slow that I had to go to PVM. That runs at very good speeds and I've stopped noticing the virtualization. The only problem I have is managing the hypervisor bits, because they're out of tree. Now, perhaps that could be fixed. Someone told me that older HVM boxen can't be fixed; you need a very recent VMX/SVM to perform well. But if it is fixable, then perhaps future plans shouldn't worry about it. The second machine is pre-HVM by a short period. It is not even three years old. I can't run HVM on it, at all. I can either run PVM or I can't virtualize. It has fast CPUs and many GB of RAM. I can do an entire four node cluster test on it, with serious (read, memory intensive) software. In a PVM-less world, this machine becomes a single cluster node, and I have to go find three more machines. Of course, if I had infinite machines, I wouldn't be worrying about this at all. So I want to see PVM continue for a long time. I'd like it to be something I can get with mainline Linux. I don't care if it is dom0, dom0 and the hypervisor, whatever. I just don't want to have to be patching out-of-tree patches for a pretty basic functionality. I don't see 2-3 years as a time frame to assume "everyone has one." Otherwise, why does Linux have code for x86_32? Everyone's had a 64bit system for at least that long. Sure, that's a straw man. It goes both ways. Like Chris said, if we have technical hurdles for Xen to cross, let's get them out in the open and fixed. If previous Xen developer interaction has left a bad taste in people's mouths, then the current crew has to make it up to us. But we have to be willing to notice they're doing so. At the end of the day, I want to use Linux on my systems. Joel -- "I almost ran over an angel He had a nice big fat cigar. 'In a sense,' he said, 'You're alone here So if you jump, you'd best jump far.'" Joel Becker Principal Software Developer Oracle E-mail: joel.becker@oracle.com Phone: (650) 506-8127 -- 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/