Deadline miss in periodic tasks

Fered a_Fered at
Fri Sep 7 15:22:48 UTC 2012

 Joel Sherrill wrote:
> On 09/07/2012 02:14 AM, Fered wrote:
> > Hi;
> > 
> > In periodic tasks, if a task misses its deadline at middle of its
> > execution, is the task stopped or it continues and just the
> > rtems_rate_monotonic_period() function returns RTEMS_TIMEOUT?
> If you are using the Deterministic Priority Scheduler (default)
> or the Earliest Deadline First, this is the case.
> If you are using the Constant Bandwidth Scheduler algorithm,
> then it can detect when a thread is not going to make its
> deadline and give you options to deal with that.
> But in general, the task continues to execute after the period.
> There is no magic way for RTEMS to make you go back to
> the top of the loop without the user callbacks supported by the
> CBS algorithm. When you get the RTEMS_TIMEOUT, you have
> to know what that means to that task.
> > Thanks.
> > _______________________________________________
> > rtems-users mailing list
> > rtems-users at
> >
> --
> Joel Sherrill, Ph.D.             Director of Research&   Development
> joel.sherrill at        On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>      Support Available             (256) 722-9985

Thank you Joel.

If the task continues after deadline, then next periods will be shifted. Is it 
How can I use EDF scheduler? I should assign priorities according to periods 
or there is some facilities in RTEMS?
How can I use Constant Band Scheduler? I should implement it myself?

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