| Re: [ckrm-tech] [PATCH 3/9] Containers (V9): Add tasks file interface [message #12513 is a reply to message #12505] |
Wed, 02 May 2007 03:17   |
Srivatsa Vaddagiri
Messages: 241
Registered: August 2006
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Senior Member |
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On Tue, May 01, 2007 at 01:37:24PM -0700, Paul Menage wrote:
> > Any chance we could get a per-container task list? It will
> > help subsystem writers as well.
>
> It would be possible, yes - but we probably wouldn't want the overhead
> (additional ref counts and list manipulations on every fork/exit) of
> it on by default. We could make it a config option that particular
> subsystems could select.
>
> I guess the question is how useful is this really, compared to just
> doing a do_each_thread() and seeing which tasks are in the container?
> Certainly that's a non-trivial operation, but in what circumstances is
> it really necessary to do it?
For the CPU controller I was working on, (a fast access to) such a list would
have been valuable. Basically each task has a weight associated with it
(p->load_weight) which is made to depend upon its class limit. Whenever
the class limit changes, we need to go and change all its member task's
->load_weight value.
If you don't maintain the per-container task list, I guess I could still
work around it, by either:
- Walk the task table and find relevant members, OR better
perhaps
- Move p->load_weight to a class structure
--
Regards,
vatsa
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