About the rate_monotonic_manager

Kuan Hsun Chen kuan-hsun.chen at tu-dortmund.de
Wed Jul 1 20:21:53 UTC 2015

Hello everyone,

Does Rate Monotonic Manager update the priorities of tasks and suspend the
lower priority task accordingly?

In C_user manual, I cannot find any description about the priority
management in Chapter 10.
Therefore, I assume RM has the scheduler to handle the priority according
to the registered tasks periods as the common design in the most of
real-time literature.

After using Rate Monotonic Manager APIs, indeed, I can have the periodic
task executions.
Moreover, I also have tried on the semaphore to reappear the priority
inversion case.
However, I cannot observe the preemption scenario by using Rate Monotonic
Manager, if all the initial priorities in rtems_task_create() are set to 1.
Even if I set up the priorities of tasks manually, it seems to me that Rate
Monotonic Manager doesn't really suspend the task properly.

I have checked that the task attribute and task mode allow the preemption.
Instead of the example_v2/triple period case (one task with RM), I cannot
find any example including multitasking with RM scheduling.

Do you have the same issue or any useful reference?
Probably I misunderstand the meaning of APIs usage...

Many thanks,

M.Sc. Kuan-Hsun Chen

TU Dortmund
Department of Computer Science 12
Design Automation of Embedded Systems
Otto-Hahn-Strasse 16, Room 102

44227 Dortmund

Phone:  *+49 231 755 6124*
Mail:   kuan-hsun.chen at tu-dortmund.de <kuan-hsun.chen at tu-dortmund.de>
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