cgconfig.conf

group an {
       perm {
                admin {
                        uid = root;
                        gid = root;
                }
                task {
                        uid = libvirt-qemu;
                        gid = kvm;
                }
       }
       memory {
                memory.limit_in_bytes = 20G;
                memory.use_hierarchy = 1;
      }
}


cgrules.conf

ibvirt-qemu            memory          an