From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nathan Lynch Subject: Re: bugs with ckpt-v15-dev Date: Mon, 18 May 2009 18:21:22 -0500 Message-ID: References: <20090518211041.GA20781@us.ibm.com> <20090518225100.GC28083@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090518225100.GC28083-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> (Matt Helsley's message of "Mon\, 18 May 2009 15\:51\:00 -0700") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Matt Helsley Cc: Containers List-Id: containers.vger.kernel.org Matt Helsley writes: > On Mon, May 18, 2009 at 04:36:11PM -0500, Nathan Lynch wrote: >> >> [1] Should CONFIG_CHECKPOINT depend on CONFIG_CGROUPS and/or >> CONFIG_CGROUPS_FREEZER? We require tasks to be put in frozen state >> before checkpoint, is there any mechanism apart from >> cgroup/freezer.state to do this? > > Have you tried sending all of the tasks SIGSTOP? It won't 100% freeze > the tasks -- they'd still be capable of responding to some signals > (CONT, TERM..). Also they'd presumably be placed in the stopped state > upon restart so a SIGCONT will be needed. In the case of bash, at > least, that will technically change what happens upon restart. My > guess is that in many cases it won't matter but there are some where > it will. Hmm, I'm having trouble understanding your suggestion. The current checkpoint implementation requires non-self tasks to be frozen (p->flags & PF_FROZEN), which is not equivalent to stopped state (task->state & __TASK_STOPPED). That is, it would refuse to checkpoint tasks in stopped state. See may_checkpoint_task().