From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH REPOST RFC cgroup/for-3.7] cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them Date: Fri, 14 Sep 2012 12:19:06 +0400 Message-ID: <5052E87A.1050405@parallels.com> References: <20120910223125.GC7677@google.com> <20120910223355.GD7677@google.com> <20120911100433.GC8058@dhcp22.suse.cz> <5050568B.9090601@parallels.com> <20120912154907.GW21579@dhcp22.suse.cz> <20120912171120.GP7677@google.com> <20120913121438.GC8055@dhcp22.suse.cz> <20120913171832.GY7677@google.com> <20120913173958.GA21381@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120913173958.GA21381-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org> List-Id: 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: Michal Hocko Cc: Neil Horman , "Serge E. Hallyn" , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Thomas Graf , Paul Mackerras , "Aneesh Kumar K.V" , Arnaldo Carvalho de Melo , Johannes Weiner , Tejun Heo , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Paul Turner , Ingo Molnar , Vivek Goyal On 09/13/2012 09:39 PM, Michal Hocko wrote: > On Thu 13-09-12 10:18:32, Tejun Heo wrote: >> Hello, Michal. >> >> On Thu, Sep 13, 2012 at 02:14:38PM +0200, Michal Hocko wrote: >>> I would like to see use_hierarchy go away. The only concern I have is >>> to warn only if somebody is doing something wrong (aka flat >>> hierarchies). Or better put it this way. Do not warn in cases which do >>> not change if use_hierarchy is gone or default changes to 1. >>> An example: >>> root (use_hierarchy=0) >>> | \ >>> | A (use_hierarchy=0) >>> | >>> B (use_hierarachy=1) >>> |\ >>> C D >>> >>> is a perfectly sane configuration and I do not see any reason to fill >>> logs with some scary warnings when A is created. There will be no >>> semantical change in this setup When use_hierchy is gone. >>> >>> So the only thing I am proposing here is to warn only if something >>> should be fixed in the configuration in order to be prepared for fully >>> hierarchical (and that is a second level of children from root with >>> use_hierachy==0). >>> >>> Does it make more sense now? >> >> Ah, okay, so what you're saying is that we shouldn't warn if 0 >> .use_hierarchys don't make any behavior difference from when they're >> all 1, right? > > Exactly. 1st level of children under the root is exactly this kind of > setup. > >> If so, I have no objection. Will incorporate your updated version. > > Thanks! > I want oppose it as well, but I believe part of this exercise is to make the need to have hierarchy widespread. Warning on the case 1st-level-only case helps with that, even if we make more noise than we should. The reason I supported Tejun's proposal originally, is that I think that if we make the wrong amount of noise, being wrong by a surplus is better than being wrong by a deficit, in this case.