[Lxc-users] not separeted resources

[Nirmal Guhan]

On Mon, Jul 12, 2010 at 10:20 AM, Daniel Lezcano <daniel.lezcano at free.fr> wrote:
> On 07/12/2010 06:25 PM, atp wrote:
>>
>> Nirmal,
>>
>>
>>
>>>>
>>>>   Per container/per cgroup resource tracking has not been implemented.
>>>>
>>>
>>> I think only the *tracking* has not been implemented. It would still
>>> be possible to configure resources per container using cgroup (cpuset,
>>> memory etc.) Please confirm.
>>>
>>
>>    Yes, resource constraint has been implemented. That is the main
>> purpose of control groups. The tracking of resource consumption by
>> control group (as a container has a control group associated with it)
>> has not been done.
>>
>>   Apologies if I was unclear. As always this is based off my
>> understanding. Please correct me if I'm wrong.
>>
>
> The process tracking is the cgroup itself. The different controllers are
> plugged on this framework, these are known as subsystems and they make use
> of the cgroup process tracking to assign, account, restrict some resources.
>
> The existing subsystems are:
>
>  * physical and swap memory : assign an amount of physical memory
>  * network traffic control : choose network traffic bandwidth and network
> priority between cgroups
>  * cpuset : assign cpus (exclusive or not)
>  * freezer : block all the processes of the container
>  * cgroup scheduling : a "nice" at the cgroup level
> * and some accounting informations about the cpus and the memory used
>
> The container is tied with a cgroup, so for example if you assign a cgroup
> scheduling priority higher to another container, this one will be less
> responsive than the one competing with it.
>
> lxc gives a thin abstraction layer between the container and the cgroup, it
> is up to the user to know the container subsystems in order to assign the
> right values. That has the advantage to have the lxc code agnostic with the
> cgroup file system moving interface.
>
> The next subsystems and cgroup features are the io nice per cgroup and an
> event file to notify for example the memory has reached a limit. AFAICS it
> is for 2.6.35.
>
> Unfortunately, the cgroup like the proc fs are not container aware and
> several times people is complaining they don't understand why when they set
> the physical memory to 256MB via the cgroup, they don't see the same value
> in /proc/meminfo ?

I read this as the reporting is not virtualized for container but
limits will still apply per container. For instance I can configure
256MB physical memory for container but  it won't show up in meminfo
or free. The physical limit will still apply. Did I misread?
Please clarify. Also let me know if all the cgroup subsystems
(network, cpuset, memory etc.) work with lxc containers i.e I can set
limits. This will help me make a conscious choice. Appreciate your
help.

--Nirmal

>
> I don't think there is a nice solution for this right now, and as Andrew
> said we experienced with the fuse /proc overriding the /proc but it showed
> quickly its limits.
>
> Thanks
>  -- Daniel
>
>