Joel Sherrill <joel@OARcorp.com> joel.sherrill at OARcorp.com
Sat Jun 5 14:50:49 UTC 2004

Feng, Shuchen wrote:
> Joel Sherrill wrote:
>>Your comment "big and complicated" makes me wonder if the VxWorks
>>semantics are slightly different from that of RTEMS.  What does
>>their documentation say about what happens in relation to the calling
>>task and higher and lower priority threads?
> At this point, comapring the document I have in hand, I think the
> semantics between the two are the same.
> Further tests showed that the bug does not seem to be related to
> this thread.  It is just application related timing issue.

CHanging between RTEMS and VxWorks would certainly be enough to
perturb the timing of the application and uncover new windows
in it.  I certainly have seen this lots of ways before.

> I believe (without checking document), for RTEMS, the preemptive
> scheduler is based on priorities, and highest priority task ready
> to run (not pended or delayed) is allocated the CPU, right ?

Exactly with the caveat that tasks can be made non-preemptible.
The longer discussion of this is here:


> Thanks,
> Kate

Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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