DevConf.CZ 2020

The switch to the new hierarchy has been long in the making, with initial kernel support 5 years ago.
There are good technical reasons for the change, but the ecosystem has been slow to switch.
Docker has no support, other container runtimes have partial support, with many pull requests in flight.
Fedora 31 now has the new hierarchy as default.

The switch opens new possibilities: fully hierarchical controllers can be delegated safely,
resource allocation is more robust, we get better statistics about CPU and memory,
new controllers allow better utilization (work-conservation).

BPF programs attached to cgroups to provide futures that would have to be implemented in the kernel.
Systemd uses this to implement a device filter to replace the old devices cgroup controller,
and packet filters that replace the global firewall.

This talk will show the technical advantages and support in systemd and containers and report on the
switch in Fedora.