Re: [libvirt] [PATCH v2 14/53] vircgroup: introduce virCgroupV2MakeGroup

When creating cgroup hierarchy we need to enable controllers in the parent cgroup in order to be usable. That means writing "+{controller}" into cgroup.subtree_control file. We can enable only controllers that are enabled for parent cgroup, that means we need to do that for the whole cgroup tree. Cgroups for threads needs to be handled differently in cgroup v2. There are two types of controllers: - domain controllers: these cannot be enabled for threads - threaded controllers: these can be enabled for threads In addition there are multiple types of cgroups: - domain: normal cgroup - domain threaded: a domain cgroup that serves as root for threaded cgroups - domain invalid: invalid cgroup, can be changed into threaded, this is the default state if you create subgroup inside domain threaded group or threaded group - threaded: threaded cgroup which can have domain threaded or threaded as parent group In order to create threaded cgroup it's sufficient to write "threaded" into cgroup.type file, it will automatically make parent cgroup "domain threaded" if it was only "domain". In case the parent cgroup is already "domain threaded" or "threaded" it will modify only the type of current cgroup. After that we can enable threaded controllers. Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; --- src/util/vircgroup.c | 2 +- src/util/vircgroupbackend.h | 1 + src/util/vircgroupv2.c | 76 +++++++++++++++++++++++++++++++++++++ 3 files changed, 78 insertions(+), 1 deletion(-)