RE: [ECOS] cyg_semaphore_post

[Robin Farine <robin dot farine at acn-group dot ch>]

On Mon, 2002-02-11 at 16:10, Woller, Thomas wrote:
> we are also wondering how to handle the non-priority based (ie.
> FIFO based) waiting under eCos. when there are a series of
> threads waiting on the same semaphore, we basically want the
> highest priority thread to run, NOT the first one that happened
> to wait on the semaphore.  some of our current s/w on another
> RTOS that we are porting over currently supports both FIFO and
> priority based semaphores/mutexes. so we think that core
> modifications are the only option we have. we could just allow
> the lower priority threads, that are first on the FIFO, to cycle
> out with context switches at the most every system tick. not sure
> if this is going to be too much latency for the higher priority
> thread though, we'll have to test and see.
> tom
> 

You might try a mutex, a condition variable and an appropriate priority
inversion protection protocol instead of a counting semaphore.

[snip]

Robin



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