[Xenomai-core] Re: [Xenomai-help] Limiting Xenomai tasks to one certain core in a dual core system

[Jan Kiszka <jan.kiszka@domain.hid>]

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M. Koehrer wrote:
> Hi all,
> 
> I want to run Xenomai and rtnet (using RTDM) on a dual core CPU.
> Using the kernel parameter isolcpus I can force the standard Linux tasks
> to run on one of the cores.
> The other core should be used exclusively by all real time tasks (including rtnet).
> I can - of course - pass a parameter on each rt_task_create() call.
> However how can I force rtnet (using RTDM) to run on this CPU core?

You hit a weak point, see the Task Market in the wiki: "CPU affinity for
RTDM threads." We both need an API for RTDM and its application on
RTnet. Not complex work, just work...

> Is there a possibility to mask the CPUs to be used globally?
> This could also avoid to pass the CPU number with each rt_task_create() call.

Well, that would actually be an additional way. Yeah, maybe some global
CPU mask that controls the affinity on future thread creation. We could
export it via /proc so that you can set it right before starting a
specific group of applications and drivers.

On the long term, a control interface to the Xenomai scheduler would be
good so that things like policy, priority, time-slice, or CPU affinity
could be manipulated with some command line tool or via /proc after
thread creation.

Further feedback welcome!

Jan


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