[systemd-devel] How does hybrid cgroup setup work?

[Lennart Poettering]

On Sa, 28.10.17 22:01, Umut Tezduyar Lindskog (umut at tezduyar.com) wrote:

> Hello,
> 
> I am trying to have cpu controller on v1 and memory controller on
> unified but it is not working the way I am expecting. When I enable
> CONFIG_MEMCG, cgroup is popping up in /proc/cgroups and
> mount_cgroup_controllers() is mounting it very early. Once it is
> mounted in v1, it becomes unavailable in v2.
> 
> Did I misunderstand how hybrid works?

hybrid means that v2 is used only for tracking services (which is a
good thing, since it provides safe notification of when a cgroup
exits), but not for any of the controllers. That means hybrid mode is
mostly compatible with pure v1, except that there's yet another
hierarchy (the v2 one) and systemd uses it for its own purposes.

Lennart

-- 
Lennart Poettering, Red Hat