From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755435AbYICOUO (ORCPT ); Wed, 3 Sep 2008 10:20:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754429AbYICOUB (ORCPT ); Wed, 3 Sep 2008 10:20:01 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:45459 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754276AbYICOUA (ORCPT ); Wed, 3 Sep 2008 10:20:00 -0400 Date: Wed, 3 Sep 2008 09:18:41 -0500 From: "Serge E. Hallyn" To: Cedric Le Goater Cc: Andrey Mirkin , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/9] OpenVZ kernel based checkpointing/restart Message-ID: <20080903141841.GA13425@us.ibm.com> References: <1220439476-16465-1-git-send-email-major@openvz.org> <48BE82F9.4020808@fr.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48BE82F9.4020808@fr.ibm.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Cedric Le Goater (clg@fr.ibm.com): > Andrey Mirkin wrote: > > This patchset introduces kernel based checkpointing/restart as it is > > implemented in OpenVZ project. This patchset has limited functionality and > > are able to checkpoint/restart only single process. Recently Oren Laaden > > sent another kernel based implementation of checkpoint/restart. The main > > differences between this patchset and Oren's patchset are: > > > > * In this patchset checkpointing initiated not from the process > > (right now we do not have a container, only namespaces), Oren's patchset > > performs checkpointing from the process context. > > > > * Restart in this patchset is initiated from process, which restarts a new > > process (in new namespaces) with saved state. Oren's patchset uses the same > > process from which restart was initiated and restore saved state over it. > > > > * Checkpoint/restart functionality in this patchset is implemented as a kernel > > module > > why ? Do we really think that C/R implementations will be so different that > we will need C/R ops to support all of them ? I imagine that there could be > different models : At the mini-summit two reasons were brought up to make it a module: 1. So sysadmins worried about security implications can completely unload the module 2. So developers can unload and reload the module while testing. > 1. brute force : dump it all and kill > 2. incremental > 3. live migration > ... Actually I don't think we expected to use different implementations for those. > But I see all of them really tied to the kernel internals. > > The first issues I see with this direction are some EXPORT_SYMBOL() that would > be useless without a module. > > > As checkpointing is initiated not from the process which state should be saved > > we should freeze a process before saving its state. Right now Container Freezer > > from Matt Helsley can be used for this. > > OK that's integrated and Daniel's tools : > > http://lxc.cvs.sourceforge.net/lxc/ > > one more reason to work on integration :) > > C. > > > > This patchset introduce only a concept how kernel based checkpointing/restart > > can be implemented and are able to checkpoint/restart only a single process > > with simple VMAs. > > > > I've tried to split my patchset in small patches to make review more easier. > > _______________________________________________ > > Containers mailing list > > Containers@lists.linux-foundation.org > > https://lists.linux-foundation.org/mailman/listinfo/containers > > > > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/containers