From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756356AbZB0JTb (ORCPT ); Fri, 27 Feb 2009 04:19:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753987AbZB0JTQ (ORCPT ); Fri, 27 Feb 2009 04:19:16 -0500 Received: from mtagate2.de.ibm.com ([195.212.17.162]:57998 "EHLO mtagate2.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753718AbZB0JTO (ORCPT ); Fri, 27 Feb 2009 04:19:14 -0500 Subject: Re: How much of a mess does OpenVZ make? ;) Was: What can OpenVZ do? From: Greg Kurz To: Alexey Dobriyan Cc: Ingo Molnar , linux-api@vger.kernel.org, containers@lists.linux-foundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, Dave Hansen , linux-mm@kvack.org, viro@zeniv.linux.org.uk, mpm@selenic.com, Andrew Morton , torvalds@linux-foundation.org, tglx@linutronix.de, xemul@openvz.org In-Reply-To: <20090226221709.GA2924@x200.localdomain> References: <20090211141434.dfa1d079.akpm@linux-foundation.org> <1234462282.30155.171.camel@nimitz> <1234467035.3243.538.camel@calx> <20090212114207.e1c2de82.akpm@linux-foundation.org> <1234475483.30155.194.camel@nimitz> <20090212141014.2cd3d54d.akpm@linux-foundation.org> <1234479845.30155.220.camel@nimitz> <20090226162755.GB1456@x200.localdomain> <20090226173302.GB29439@elte.hu> <1235673016.5877.62.camel@bahia> <20090226221709.GA2924@x200.localdomain> Content-Type: text/plain Date: Fri, 27 Feb 2009 10:19:09 +0100 Message-Id: <1235726349.4570.7.camel@bahia> Mime-Version: 1.0 X-Mailer: Evolution 2.24.4 (2.24.4-1.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2009-02-27 at 01:17 +0300, Alexey Dobriyan wrote: > On Thu, Feb 26, 2009 at 07:30:16PM +0100, Greg Kurz wrote: > > On Thu, 2009-02-26 at 18:33 +0100, Ingo Molnar wrote: > > > I think the main question is: will we ever find ourselves in the > > > future saying that "C/R sucks, nobody but a small minority uses > > > it, wish we had never merged it"? I think the likelyhood of that > > > is very low. I think the current OpenVZ stuff already looks very > > > > We've been maintaining for some years now a C/R middleware with only a > > few hooks in the kernel. Our strategy is to leverage existing kernel > > paths as they do most of the work right. > > > > Most of the checkpoint is performed from userspace, using regular > > syscalls in a signal handler or /proc parsing. Restart is a bit trickier > > and needs some kernel support to bypass syscall checks and enforce a > > specific id for a resource. At the end, we support C/R and live > > migration of networking apps (websphere application server for example). > > > > >From our experience, we can tell: > > > > Pros: mostly not-so-tricky userland code, independent from kernel > > internals > > Cons: sub-optimal for some resources > > How do you restore struct task_struct::did_exec ? With sys_execve(). -- Gregory Kurz gkurz@fr.ibm.com Software Engineer @ IBM/Meiosys http://www.ibm.com Tel +33 (0)534 638 479 Fax +33 (0)561 400 420 "Anarchy is about taking complete responsibility for yourself." Alan Moore.