cgroup handling
currently we try to use cgroup to do some limiting when compressing the images, however, there are different options based on different versions, so similar to the way we handle systemd, we need to do with cgroups.
currently we try to use cgroup to do some limiting when compressing the images, however, there are different options based on different versions, so similar to the way we handle systemd, we need to do with cgroups.