Provide a usage example, update the bind() callback API, etc. Signed-off-by: Li Zefan <l...@cn.fujitsu.com> --- Documentation/cgroups/cgroups.txt | 37 +++++++++++++++++++++++++++++-------- 1 files changed, 29 insertions(+), 8 deletions(-)
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 190018b..4e772cc 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -363,17 +363,23 @@ Note this will add ns to the hierarchy but won't remove memory or cpuset, because the new options are appended to the old ones: # mount -o remount,ns /dev/cgroup +For some subsystems you can bind them to a mounted hierarchy or +remove them from it, even if there're sub-cgroups in it: +# mount -t cgroup -o freezer hier1 /dev/cgroup +# echo $$ > /dev/cgroup/my_cgroup +# mount -o freezer,cpuset hier1 /dev/cgroup +(failed) +# mount -o freezer,cpuacct hier1 /dev/cgroup +# mount -o cpuacct hier1 /dev/cgroup + +Note cpuacct should be sit in the default hierarchy before remount. + To Specify a hierarchy's release_agent: # mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \ xxx /dev/cgroup Note that specifying 'release_agent' more than once will return failure. -Note that changing the set of subsystems is currently only supported -when the hierarchy consists of a single (root) cgroup. Supporting -the ability to arbitrarily bind/unbind subsystems from an existing -cgroup hierarchy is intended to be implemented in the future. - Then under /dev/cgroup you can find a tree that corresponds to the tree of the cgroups in the system. For instance, /dev/cgroup is the cgroup that holds the whole system. @@ -523,6 +529,15 @@ module initcall a call to cgroup_load_subsys(), and in its exitcall a call to cgroup_unload_subsys(). It should also set its_subsys.module = THIS_MODULE in its .c file. +If a subsystem has bindable flag set, normally it has to be able to +support side-effect free movement of a task into any just-created +cgroups. i.e. it's probably not suitable for any subsystem where +can_attach() might return false for the newly-created cgroup, or +attach() might have side-effects for those same cases. + +If a subsystem has unbindable flag set, normally it has to be able to +support side-effect free movement of a task into the roog cgroup. + Each subsystem may export the following methods. The only mandatory methods are create/destroy. Any others that are null are presumed to be successful no-ops. @@ -627,9 +642,15 @@ void bind(struct cgroup_subsys *ss, struct cgroup *root) (cgroup_mutex and ss->hierarchy_mutex held by caller) Called when a cgroup subsystem is rebound to a different hierarchy -and root cgroup. Currently this will only involve movement between -the default hierarchy (which never has sub-cgroups) and a hierarchy -that is being created/destroyed (and hence has no sub-cgroups). +and root cgroup. + +For non-bindable subsystems, this will only involve movement +between the default hierarchy (which never has sub-cgroups) and a +hierarchy that is being created/destroyed (and hence has no sub-cgroups). + +For binadable subsystems, this may also involve movement between the +default hierarchy and a mounted hierarchy that's populated with +sub-cgroups. 4. Questions ============ -- 1.6.3 _______________________________________________ Containers mailing list contain...@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel
