+ 

+ [[cgroups-v2-by-default]]

+ == Fedora now uses cgroups-v2 by default

+ 

+ Enablement of *control groups version 2* (`cgroups-v2`) by default allows the system utilities to conveniently take advantage of new functionality and fixes this kernel feature brings.

+ 

+ Users have to update any tools or scripts they used for manual configuration of `cgroups-v1` so that they reflect `cgroups-v2` now. The tools or scripts should not require any changes, if they utilized the `systemd` interfaces. 

+ 

+ Some container engines leak the control group hierarchy into containers. This could pose a problem for container images that expect to be running in a *control group version 1* environment. 

+ 

+ [NOTE]

+ ====

+ To retain the old default of *control groups version 1* (`cgroups-v1`), set the following kernel command line parameter:

+ 

+ 	`systemd.unified_cgroup_hierarchy=0`

+ ====

+