Re: [PATCH v4 cgroup/for-3.7] cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them

Glauber Costa
2012-09-14T09:17:14Z

On 09/14/2012 01:14 PM, Glauber Costa wrote:
> On 09/14/2012 12:03 AM, Tejun Heo wrote:
>> Hello, Vivek.
>>
>> On Thu, Sep 13, 2012 at 03:41:11PM -0400, Vivek Goyal wrote:
>>> I think for blkio controller, first level of creation itself is wrong if
>>> hierarchy is not supported.
>>>
>>> root
>>> / | \
>>> T1 T2 G1
>>>
>
> I side with Vivek, and I think we should warn first level. It just tends
> to be wrong. If memcg is a special case, just special case it.
> _but_, I see no reason not to do it.
>
> While I agree with Michal point that this is not necessary, I don't
> think being noisier than we need to be is a crime. Less noisy certainly
> can be.
>

To add to that: If it is "all the same", hierarchy should be set to 1.
If anything else, this will make people switch it to shut up the
warning, and prevent a potentially broken use case to appear in the future.