From: Li Zefan 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: Tue, 11 Sep 2012 20:38:51 +0800 Message-ID: <504F30DB.60808@huawei.com> References: <20120910223125.GC7677@google.com> <20120910223355.GD7677@google.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120910223355.GD7677-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michal Hocko , Glauber Costa , Peter Zijlstra , Paul Turner , Johannes Weiner , Thomas Graf , "Serge E. Hallyn" , Vivek Goyal , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Neil Horman , "Aneesh Kumar K.V" On 2012/9/11 6:33, Tejun Heo wrote: > (forgot cc'ing containers / cgroups mailing lists and used the old > address for Li. Reposting. Sorry for the noise.) > > Currently, cgroup hierarchy support is a mess. cpu related subsystems > behave correctly - configuration, accounting and control on a parent > properly cover its children. blkio and freezer completely ignore > hierarchy and treat all cgroups as if they're directly under the root > cgroup. Others show yet different behaviors. > > These differing interpretations of cgroup hierarchy make using cgroup > confusing and it impossible to co-mount controllers into the same > hierarchy and obtain sane behavior. > > Eventually, we want full hierarchy support from all subsystems and > probably a unified hierarchy. Users using separate hierarchies > expecting completely different behaviors depending on the mounted > subsystem is deterimental to making any progress on this front. > > This patch adds cgroup_subsys.broken_hierarchy and sets it to %true > for controllers which are lacking in hierarchy support. The goal of > this patch is two-fold. > > * Move users away from using hierarchy on currently non-hierarchical > subsystems, so that implementing proper hierarchy support on those > doesn't surprise them. > > * Keep track of which controllers are broken how and nudge the > subsystems to implement proper hierarchy support. > > For now, start with a single warning message. We can whine louder > later on. > > (I tried to document what's broken and how it should be fixed. If I > got something wrong, please let me know.) > So isn't cpuset broken too? child cpuset's cpu mask isn't necessary a subset of the parent's if the cpu_exclusive flag is not set.