- cgroup.procs: list of tgids in the cgroup. This list is not
guaranteed to be sorted or free of duplicate tgids, and userspace
should sort/uniquify the list if this property is required.
- Writing a tgid into this file moves all threads with that tgid into
- this cgroup.
+ This is a read-only file, for now.
- notify_on_release flag: run the release agent on exit?
- release_agent: the path to use for release notifications (this file
exists in the top cgroup only)