From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757949AbYDDOLT (ORCPT ); Fri, 4 Apr 2008 10:11:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755712AbYDDOLK (ORCPT ); Fri, 4 Apr 2008 10:11:10 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:50578 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755605AbYDDOLI (ORCPT ); Fri, 4 Apr 2008 10:11:08 -0400 Date: Fri, 4 Apr 2008 09:11:06 -0500 From: "Serge E. Hallyn" To: Paul Menage Cc: matthltc@us.ibm.com, Linux Containers , Linux-Kernel Subject: Re: [Devel] [RFC PATCH 0/4] Container Freezer: Reuse Suspend Freezer Message-ID: <20080404141106.GA9977@sergelap.austin.ibm.com> References: <20080403210316.397506379@us.ibm.com> <6599ad830804031649p6bbc60f3s59fb7c25a7260505@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6599ad830804031649p6bbc60f3s59fb7c25a7260505@mail.gmail.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Paul Menage (menage@google.com): > On Thu, Apr 3, 2008 at 2:03 PM, wrote: > > > > * "freezer.kill" > > > > writing will send signal number to all tasks > > > > My first thought (not having looked at the code yet) is that sending a > signal doesn't really have anything to do with freezing, so it > shouldn't be in the same subsystem. Maybe a separate subsystem called > "signal"? > > And more than that, it's not something that requires any particular > per-process state, so there's no reason that the subsystem that > provides the "kill" functionality shouldn't be able to be mounted in > multiple hierarchies. > > How about if I added support for stateless subsystems, that could > potentially be mounted in multiple hierarchies at once? They wouldn't > need an entry in the css set, since they have no state. > > > * Usage : > > > > # mkdir /containers/freezer > > # mount -t container -ofreezer freezer /containers/freezer > > # mkdir /containers/freezer/0 > > # echo $some_pid > /containers/freezer/0/tasks > > > > to get status of the freezer subsystem : > > > > # cat /containers/freezer/0/freezer.freeze > > RUNNING > > > > to freeze all tasks in the container : > > > > # echo 1 > /containers/freezer/0/freezer.freeze > > # cat /containers/freezer/0/freezer.freeze > > FREEZING > > # cat /containers/freezer/0/freezer.freeze > > FROZEN > > Could we separate this out into two files? One called "freeze" that's > a 0/1 for whether we're intending to freeze the subsystem, and one > called "frozen" that indicates whether it is frozen? And maybe a > "state" file to report the RUNNING/FREEZING/FROZEN distinction in a > human-readable way? One thing Oren had mentioned for checkpoint/restart was having more states - i.e. restoring, checkpointing... So then (assuming we used this subsys for that) we'd have more than the two files. Which is probably fine, just wanted to point that out. -serge