[Devel] Re: [PATCH 1/4] Virtualization/containers: introduction

[Eric W. Biederman]

Hubertus Franke <frankeh at watson.ibm.com> writes:
>
> Agreed.. here are some issued we learned from other projects that had
> similar interception points.
>
> Having a central umbrella object (let's stick to the name container)
> is useful, but being the only object through which every access has to
> pass may have drawbacks..
>
> task->container->pspace->pidmap[offset].page   implies potential
> cachemisses etc.
>
> If overhead becomes too large, then we can stick (cache) the pointer
> additionally in the task struct. But ofcourse that should be carefully
> examined on a per subsystem base...

Ok. After talking with the vserver guys on IRC.  I think grasp the
importance.  The key feature is to have a place to put limits and the
like for your entire container.  Look at all of the non-signal stuff
in struct signal for an example.  The nested namespaces seem to
be just an implementation detail.

For OpenVZ having the other namespaces nested may have some
importance.  I haven't gotten their yet.

The task->container->pspace->.... thing feels very awkward to me,
and feels like it increases our chance getting a cache miss.

So I support the concept of a place to put all of the odd little
things like rlimits for containers.  But I would like to flatten
it in the task_struct if we can.


Eric