Re: [Xenomai-help] Have condition variables Priority Inheritance Protection (PIP)?

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

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Rodrigo Rosenfeld Rosas wrote:
> Em Sexta 28 Abril 2006 17:42, Jan Kiszka escreveu:
> 
>> ...
>>> Could someone please point me the reason?
>> Just as with semaphores: there is no ownership concept for condition
>> variables. Thus, who should be boosted to your priority in case you
>> decide to wait on such a resource?
> 
> Sorry, you are right. Xenomai has no way of knowing which tasks could signal 
> the condition variable. If I wanted to wait on some resource using priority 
> inheritance I guess I would have to raise the priority of the task owning the 
> resource manually when only one task can signal the condition variable (or 
> semaphore). Do you know other better approaches? I mean if a task A of 
> priority 50, shares a resource with task B and C, both priority 10 through 
> semaphores. Suppose B and C are using the semaphore when A requests it. How 
> could they be boosted to A's priority, so that A is protected with priority 
> inheritance and then go back to their original priorities? Or should I use 
> other IPC mechanism for sharing resource with PIP?

Mutexes were invented for such resource access control :). They have a
strict ownership concept, thus allowing to apply PIP as well.

Jan


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