RTEMS POSIX Priority Inversion Issue.

[JunBeom Kim (EmbedCoreTech)]

Dear Sir,

 

I am testing RTEMS POSIX thread priority.

I am still using RTEMS 4.12 in 2017 year.

 

There are four pthreads(main, pthread1, pthread2, pthread3) on two cores in
my test case.

- main pthread is running on core 1.

- pthread1, pthread2, pthread3 is running on core 2.

- All threads are doing GPIO toggling action in while(1) loop.

- my configuration for timeslice quantum is 25ms.

 

As I know from RTEMS POSIX manual, there is below statement.

 

In the RTEMS implementation of the POSIX API, the priorities range from the
low priority of

sched_get_priority_min() to the highest priority of
sched_get_priority_max(). Numerically

higher values represent higher priorities.

 

But, when I test this, lower value is doing as higher priority. Higher value
is doing as lower priority.

Is this correct operation ?

 

Case 0) All threads are same priority.

[/] # pthread

ID       NAME             CPU SHED PRI STATE  MODES    EVENTS WAITINFO

----------------------------------------------------------------------------
--

0b010001  main_thread       1 MEDF 2147483645 READY P:T:nA   NONE   

0b010002  pthread1           2 MEDF 2147483645 READY P:T:nA   NONE   

0b010003  pthread2           2 MEDF 2147483645 READY P:T:nA   NONE   

0b010004  pthread3           2 MEDF 2147483645 READY P:T:nA   NONE



 

Case 1) pthread3 is lower priority according to manual. But, pthread3 is
higher priority in my case.

[/] # pthread

ID       NAME             CPU SHED PRI STATE  MODES    EVENTS WAITINFO

----------------------------------------------------------------------------
--

0b010001  main_thread       1 MEDF 2147483645 READY P:T:nA   NONE   

0b010002  pthread1           2 MEDF 2147483646 READY P:T:nA   NONE   

0b010003  pthread2           2 MEDF 2147483646 READY P:T:nA   NONE   

0b010004  pthread3           2 MEDF 1789569706 READY P:T:nA   NONE



 

Case 2) pthread3 is higher priority according to manual. pthread1 and
pthread2 are higher priority than pthread3.

[/] # pthread

ID       NAME             CPU SHED PRI STATE  MODES    EVENTS WAITINFO

----------------------------------------------------------------------------
--

0b010001  main_thread       1 MEDF 2147483645 READY P:T:nA   NONE   

0b010002  pthread1           2 MEDF 1789569706 READY P:T:nA   NONE   

0b010003  pthread2           2 MEDF 1789569706 READY P:T:nA   NONE   

0b010004  pthread3           2 MEDF 2147483646 READY P:T:nA   NONE



 

Please advise.

 

Best Regards,

JunBeom Kim

~~~~~~~~~~~~~~~~~~~~~~

President / EmbedCoreTech

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Mobile:+82-10-6425-5720

Email:  <mailto:jbkim at e-coretech.kr> jbkim at e-coretech.kr 

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~~~~~~~~~~~~~~~~~~~~~~

 

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