[ECOS] cyg_semaphore_post

Chris Gray chris.gray@acunia.com
Mon Feb 11 07:56:00 GMT 2002


Robin Farine wrote:

> On Mon, 2002-02-11 at 13:38, Stijn Symons wrote:
>
> [snip]
>
> > I'm mapping an API to eCos, the API states that  "When any threads are
> > waiting on the semaphore count to become higher than zero, the thread with
> > the highest priority will be woken up to acquire the semaphore".
>
> ... which in cases of heavy load of the semaphore will lead to
> starvation of low priority threads :-\

Then don't do that. ;>

If eCos were a `hard' real-time OS, it probably would behave the way that Stijn

describes, and if starvation resulted that would be down to programming error.
The `hard' real-timers would care only that the starvation was predictable. ;>

Of course eCos isn't `hard' real-time, so eCos semaphores will not deliver the
behaviour described in Stijn's API.

Chris Gray
VM Architect, ACUNIA



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