On Tue, Jan 21, 2020 at 04:48:43PM +0100, Christian Brauner wrote: > This adds support for creating a process in a different cgroup than its > parent. Callers can limit and account processes and threads right from > the moment they are spawned: > - A service manager can directly spawn new services into dedicated > cgroups. > - A process can be directly created in a frozen cgroup and will be > frozen as well. > - The initial accounting jitter experienced by process supervisors and > daemons is eliminated with this. > - Threaded applications or even thread implementations can choose to > create a specific cgroup layout where each thread is spawned > directly into a dedicated cgroup. > > This feature is limited to the unified hierarchy. Callers need to pass > an directory file descriptor for the target cgroup. The caller can > choose to pass an O_PATH file descriptor. All usual migration > restrictions apply, i.e. there can be no processes in inner nodes. In > general, creating a process directly in a target cgroup adheres to all > migration restrictions. AFAICT, he *big* win here is avoiding the write side of the cgroup_threadgroup_rwsem. Or am I mis-reading the patch? That global lock is what makes moving tasks/threads around super expensive, avoiding that by use of this clone() variant wins the day.
