[okl4-developer] spatial and temporal partitioning control?

[Jean-Christophe Dubois]

So no opinion on this ?

JC

On Sunday 30 August 2009 18:49:11 Jean-Christophe Dubois wrote:
> Hi,
>
> Some more question on OKL4 principles:
>
> So as I understand it OKL4 is providing a good spatial partitioning
> configuration. On a SOC device we have a good granularity and we can indeed
> assign each resource to the Cell we desire.
>
> Now, I am a bit uneasy on how this would work on a non SOC device using for
> example a PCI bus or an USB bus. Would we get the ability to assign each
> PCI card/USB device to a single Cell. How should the bus
> enumeration/configuration happen? Considering the PCI enumeration could
> change the various devices physical addresses how would it work? How about
> PCI hotplug? I am not sure ... does anybody has a view on this? Or is this
> a field to explore?
>
> Still this let the temporal partitioning issue. OKL4 is mostly based on
> priority. If a high priority cell goes mad, we are stuck because it will
> eat up all of our CPU without any possibility for other cells to try to fix
> the problem. And even if we have an even higher priority cell controlling
> the all thing, how could it find that one specific cell has gone mad and
> all others cells are starving on CPU resource.
>
> Last if we are considering cells with threads of equal priority, OKL4 shall
> run these various threads in round-robin mode. But all threads will
> necessarily get the same scheduling time. I can't find an easy way to
> instruct OKL4 that for 2 threads of the same priority, one should get twice
> as much CPU time than the other one. Is there a way to allocate CPU
> resource  to the various cells/threads in a fine grained way?
>
> BTW, now that there is no more "privileged" cell (as opposed to OKL4 2.4)
> how could one cell theoretically restart another cell that is crashed/has
> gone mad? We can certainly reset the all system but is there a finer
> grained way to do it?
>
> Thanks
>
> JC
>
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