From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: Re: memcg creates an unkillable task in 3.2-rc2 Date: Mon, 29 Jul 2013 11:52:11 -0700 Message-ID: <87a9l5w65g.fsf@xmission.com> References: <20130723174711.GE21100@mtj.dyndns.org> <8761vui4cr.fsf@xmission.com> <20130729075939.GA4678@dhcp22.suse.cz> <87ehahg312.fsf@xmission.com> <20130729095109.GB4678@dhcp22.suse.cz> <20130729161026.GD22605@mtj.dyndns.org> <87r4eh70yg.fsf@xmission.com> <20130729181354.GX715@cmpxchg.org> Mime-Version: 1.0 Return-path: In-Reply-To: <20130729181354.GX715-druUgvl0LCNAfugRpC6u6w@public.gmane.org> (Johannes Weiner's message of "Mon, 29 Jul 2013 14:13:54 -0400") Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Johannes Weiner Cc: Tejun Heo , Michal Hocko , Linus Torvalds , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kent.overstreet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Li Zefan , Glauber Costa Johannes Weiner writes: > On Mon, Jul 29, 2013 at 10:03:35AM -0700, Eric W. Biederman wrote: >> Yes. From the looks of the looks of it the cgroup implementation is >> rather badly borked right now, and definitely not up to the standards of >> the other core pieces of the kernel. One of the reasons I was rather >> apalled when systemd started using them. Until the code actually works >> reliably and the races are removed most people's systems would be much >> better off with cgroups compiled out. >> >> A single unified hierarchy is a really nasty idea for the same set of >> reasons. You have to recompile to disable a controller to see if it that >> controller's bugs are what are causing problems on your production >> system. Compiles or even just a reboot is a very heavy hammer to ask >> people to use when they are triaging a problem. > > That's not how it works. You can always select which controllers you > want to mount during runtime. Unified hierarchy only means that there > is one cgroup tree for all mounted controllers, rather than every > controller having its own separate cgroup tree. > > If you are like most users and currently mount all controllers in the > same directory so that their cgroup trees overlap and appear to be a > single tree, nothing changes for you. My practical need is that I need the ability modify which controllers I am using on a per group basis. So that I can make corrall new processes in a different set of controllers than currently existing processes. I might just be missing something but I don't see how to do that with all of the controllers mounted to the same filesystem. So while I currently have a single mount of cgroupfs, and don't yet see a need for orthogonal classification of processes. To keep bugs and craziness under control I expect I will be implementing a mount of cgroupfs per controller within a month. But except for the need to limit the scope of bugs this is all getting rather badly off topic. Eric