Subject: Re: [vserver] cgroups soon incompatible with Libvirt
From: Sergiusz Pawlowicz <sergiusz@pawlowicz.name>
Date: Wed, 25 Dec 2013 02:55:43 +0000

On Mon, Dec 23, 2013 at 1:42 PM, Daniel Hokka Zakrisson
<daniel@hozac.com> wrote:
> Hi Ben,
>
> Ben Green wrote:
>> Hi all,
>>
>> I got this in my Debian updates today. It relates to libvirt, and its
>> use of cgroups:
>>
>>    If you're using cgroups make sure you're using a different mount per
>> cgroup
>>    controller (cpu, memory, ...) that is mounted to
>> /sys/fs/cgroup/<controller>.
>>    This can be achieved using mount_cgroups in /etc/default/libvirt-bin or
>> by
>>    using systemd. Using a single mount point /sys/fs/cgroup for all
>> controllers
>>    will no longer work and will prevent vms from starting. See
>>
>>    http://libvirt.org/cgroups.html
>>
>>    for more information. If you're not using cgroups nothing has to be
>> changed.
>>
>> Essentially this means that the cgroup structure libvirt will demand
>> is different to that which util-vserver demands. This will cause
>> trouble for those with mixed environments. Is anything being done
>> util-vserver side to adapt to this?
>
> The per-ss setting has existed for quite some time now to enable this
> structure.

It seems my problems related to cgroups reported to Ben few days are
essentially related to this change.

On the server where cgroups work correctly I have mounted

vserver on /dev/cgroup type cgroup
(rw,cpuset,cpu,cpuacct,memory,devices,freezer,net_cls,blkio,perf_event)

and there are subdirs with all vservers names.

On the server where cgroups do not not work I have mounted

cgroups on /sys/fs/cgroup type tmpfs (rw,uid=0,gid=0,mode=0755)

and $  ls /sys/fs/cgroup
cpu  cpuacct  devices  freezer  memory

I am not sure how to fix it and enable the structure suggested by Daniel.

cheers,
Serge