3.3. Creating Control Groups

Use the cgcreate command to create transient cgroups in hierarchies you created yourself. The syntax for cgcreate is:
cgcreate -t uid:gid -a uid:gid -g controllers:path
where:
  • -t (optional) — specifies a user (by user ID, uid) and a group (by group ID, gid) to own the tasks pseudo-file for this cgroup. This user can add tasks to the cgroup.

    Note

    Note that the only way to remove a process from a cgroup is to move it to a different cgroup. To be able to move a process, the user has to have write access to the destination cgroup; write access to the source cgroup is not necessary.
  • -a (optional) — specifies a user (by user ID, uid) and a group (by group ID, gid) to own all pseudo-files other than tasks for this cgroup. This user can modify the access to system resources for tasks in this cgroup.
  • -g — specifies the hierarchy in which the cgroup should be created, as a comma-separated list of the controllers associated with hierarchies. The list of controllers is followed by a colon and the path to the child group relative to the hierarchy. Do not include the hierarchy mount point in the path.
Because all cgroups in the same hierarchy have the same controllers, the child group has the same controllers as its parent.
As an alternative, you can create a child of the cgroup directly. To do so, use the mkdir command:
~]# mkdir /sys/fs/cgroup/controller/name/child_name
For example:
~]# mkdir /sys/fs/cgroup/net_prio/lab1/group1