Created attachment 414818 [details]
the patch

a patch from Lennart Poettering:

The patch changes the output of the cgroup column of ps, hiding all
hierarchies where the process is in the root group. Showing that a
process is not sorted into any group has very little value, and makes it
hard to find the actually interesting information in the ps output.

Or by example:

This is what 'ps xawf -eo pid,args,user,cgroup' shows without this patch:

 1209 sendmail: Queue runner@01:0 smmsp blkio:/;net_cls:/;freezer:/;devices:/;memory:/;cpuacct:/;cpu:/;ns:/;debug:/;cpuset:/;name=systemd:/systemd-1/sendmail.service

As we see quite a few controllers are active but not used by this
process. With this patch applied output looks like this:

 1209 sendmail: Queue runner@01:0 smmsp name=systemd:/systemd-1/sendmail.service

The cgroup hierarchies where the process is in the root group are
suppressed, and only the cgroup hierarchy where the process is actually
in a group is shown.