[rtl] Scheduling 2 tasks

[Volker Zahn <volker@NeRo.Uni-Bonn.DE>]

Hi RT-Freaks!

I've got a question about scheduling of periodic tasks.
I tested an example with two periodic tasks, first one has a 
scheduling time of 500us, second of 2000us withan offset of 250us
between them, so that they never come at the same time:

	rt_task_make_periodic(&task1, now + 3000, TIME_US(2000));
	rt_task_make_periodic(&task2, now + 3250, TIME_US(500));

I tested the execution times by toggling bits on the parallel port
an watching them with an oszilloscope. Worked! :)

But now I tested what happens, if task1 calculates longer than 250us.
I thought, task2 should interrupt task1, but it didn't. It came to
execution after the task_wait of task1. Is this correct, or do I things
wrong?

Of course, task2 is of higher priority, but I did change priorities with
same result.

Cheers,

  Volker
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