Base capabilities

[Daniel Waddington]

Thanks Stefan, I will take a look at this.

Daniel

On 03/21/2011 04:03 AM, Stefan Kalkowski wrote:
> Hi Daniel,
>
> that's right we doesn't pass the scheduler capability to any children.
> This is an security issue, if you simply pass the kernel's scheduler
> capability into each task, they could interfere with a global scheduling
> strategy.
>
> To circumvent this, there are two possibilities: One could put a virtual
> scheduler object's capability into the designated
> 'L4_BASE_SCHEDULER_CAP' capability slot of each task. I guess this is
> the L4re way of confining the scheduling facilities of tasks.
> The more Genode-like way, that Norman already proposed to you, is to
> extend the CPU-session interface, e.g. by an additional 'migrate' or
> 'affinity' method, so that the kernel's scheduler capability further
> resides in core, and you can use a kernel-independent interface for
> load-balancing on different CPU's or cores.
>
> I would advise you against mapping the scheduler's capability from core
> to its children, even when hacking up a prototype or example. It's
> probably not easier than extending the cpu-session interface. To use the
> scheduler for distributing threads on different cores you need in
> addition to the scheduler's capability the capability of each thread you
> like to migrate, but these also reside in the 'core' task only.
>
> I've produced a small patch for you, that extends the cpu-session
> interface (for the Fiasco.OC platform only) by a 'migrate' function,
> which doesn't do any real work - it's just a skeleton.
> Of course, we will also provide a kernel independent solution for SMP in
> the future, but if you want to get hands on experience with SMP and
> Genode/Fiasco.OC now, this might help you as a starting point.
>
> with best regards
> Stefan
>
> On 03/19/2011 01:29 AM, Daniel Waddington wrote:
>> Hi,
>> I'm trying to put in some temporary feature in Genode to set the
>> affinity of threads.  In Genode the scheduler capability
>> (L4_BASE_SCHEDULER_CAP) doesn't seem to be passed from the core to the
>> children.  Is there any obvious way to do this with the existing Genode
>> implementation - we can hack up a solution but I wanted to check first.
>>
>> Thanks
>> Daniel
>>
>>
>>
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