Docker warning on cgroup swap limit, memory.use_hierarchy
cgroup swap limit is important if you are using swap and want to enforce memory limit that includes both memory and swap. I have m/c without swap, so I never enabled it.
use_hierarchy is useful if you want reported memory usage to include memory reported by all subcgroups. eg with use_hierarchy=1, /sys/fs/cgroup/memory/parent will report memory used by processes under that cgroup and also of any subcgroups (like /sys/fs/cgroup/memory/parent/child). This is always a useful setting to enable. But its not enabled by default on most OS.
In summary, your docker containers will work fine without both of these settings. Enabling these gives you some extra benefit - esp. if you care about limit swap use and getting accurate memory reporting.