[systemd-devel] Where did DefaultControllers= option go?

[Kay Sievers]

On Tue, Oct 29, 2013 at 5:39 PM, Thomas Bächler <thomas at archlinux.org> wrote:
> Am 29.10.2013 17:21, schrieb Colin Guthrie:

>> 'Twas brillig, and Umut Tezduyar at 29/10/13 15:17 did gyre and gimble:
>>> I have noticed DefaultControllers= option is no longer in system.conf
>>> file. Has it been moved to somewhere else or are all controllers
>>> default controllers by default?
>>
>> See the various posts on this list and in blogs regarding the cgroups
>> rework. In particular see the mails with the subject "[HEADSUP] cgroup..."
>>
>> See also:
>> http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/
>
> None of this explains why systemd no longer applies certain controllers
> by default. Previously, systemd would attach cpu controllers to each
> service by default. Now, it only groups your processes in the systemd
> tree, but does not touch any cgroup controllers.
>
> The new default behaviour (or lack thereof) seems like a step back to me.

It's a property of a unit now which cgroup controllers get attached:
  http://www.freedesktop.org/software/systemd/man/systemd.resource-control.html

The global mirroring across trees makes no sense in the future. The
several independent trees will go away in the kernel next year, and
then systemd would not know what to do with an instruction like
DefaultControllers.

All implementation details of kernel cgroups are no longer exposed in
systemd, which is a huge step forward, not back.

Kay