[systemd-devel] [PATCH v2 1/4] cgroup: add the setting memory.use_hierarchy support for systemd

[Kay Sievers]

On Tue, Sep 24, 2013 at 2:42 AM, Gao feng <gaofeng at cn.fujitsu.com> wrote:
> On 09/24/2013 08:36 AM, Gao feng wrote:
>> On 09/24/2013 05:06 AM, Lennart Poettering wrote:
>>> On Mon, 23.09.13 14:30, Gao feng (gaofeng at cn.fujitsu.com) wrote:
>>>
>>>> Some programs need to set the memory.use_hierarchy(such as libvirt),
>>>> Add this feature.
>>>
>>> As mentioned already: this really shouldn't be configurable but simply
>>> the unconditional configuration that systemd requires. I have hence now
>>> commited a different patch that strictly enables this option at
>>> boot-time in the root memory hierarchy and does not turn this into yet
>>> another user config switch.
>>
>> So administrator has no rights to set use_hierarchy to false?
>
> If so, there is no need for kernel to export this file to user space.

Right, and it will go away on the kernel side with the "unified hierarchy".

Systemd must not export kernel details which we already know will not
survive in the future.

Systemd should be as close as possible to the envisioned *future*
behavior, and not to the status quo.

It makes not much sense to export knobs today in public systemd APIs,
which we expect to make no sense in the next year. Hence, we always
and unconditionally enable the hierarchy now.

Thanks,
Kay