From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFC] cgroup TODOs Date: Mon, 17 Sep 2012 09:40:02 -0700 Message-ID: <20120917164002.GA18677@google.com> References: <20120913205827.GO7677@google.com> <20120914142539.GC6221@redhat.com> <20120914213938.GV17747@google.com> <20120917150518.GB5094@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20120917150518.GB5094-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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: Vivek Goyal Cc: Neil Horman , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Serge Hallyn , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michal Hocko , Paul Mackerras , "Aneesh Kumar K.V" , Arnaldo Carvalho de Melo , Johannes Weiner , Thomas Graf , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Paul Turner , Ingo Molnar List-Id: containers.vger.kernel.org Hello, On Mon, Sep 17, 2012 at 11:05:18AM -0400, Vivek Goyal wrote: > As a developer, I will be happy to support only one model and keep code > simple. I am only concerned that for blkcg we have still not charted > out a clear migration path. The warning message your patch is giving > out will work only if we decide to not treat task and groups at same > level. It may not be enough but it still is in the right direction. > > Another problem is that configuration isn't contained in cgroup > > proper. We need a way to assign weights to individual tasks which can > > be somehow directly compared against group weights. cpu cooks > > priority for this and blkcg may be able to cook ioprio but it's nasty > > and unobvious. Also, let's say we grow network bandwidth controller > > for whatever reason. What value are we gonna use? > > So if somebody cares about settting SO_PRIORITY for traffic originating > from a tasks, move it into a cgroup. Otherwise they all get default > priority. I don't know. Do we wanna add, say, prctl for memory weight too? > So to me, leaving this decision to userspace based on their requirement > makes sense. Leaving too many decisions to userland is one of the reasons that got us into this mess, so I'm not sold on flexibility for flexibility's sake. > Yes, creating a hidden group for tasks in current group should not be > hard from implementation point of view. But again, I am concerned about > configuration of hidden group and I also don't like the idea of taking > flexibility away from user to treat tasks and group at same level. I don't know. Create a reserved directory for it? I do like the idea of taking flexibility away form user unless it's actually useful but am a bit worried we might be too late for that. :( Thanks. -- tejun