Locked tasks

Joel Sherrill joel.sherrill at OARcorp.com
Wed Jun 4 13:20:04 UTC 2003

Raja Saleru wrote:
> ITRON supports the service call rot_rdq(priority).
> with this service  can be used for round robin method.

Correct.  But this is an explicit call which means that
the task is manually controlling scheduling.  If the
caller's priority is the same as the priority passed in,
then it is functionally equivalent to the yield operations
of the other APIs -- rtems_task_wake_after(0) and 

The solutions proposed involve RTEMS scheduling handling things

One unique thing rot_rdq() can do is force a rotation on
a priority that is not the caller's.  Neat.

More below.

> regards
> Raja Saleru
> -----Original Message-----
> From: Angelo Fraietta [mailto:angelo_f at bigpond.com]
> Sent: Wednesday, June 04, 2003 8:43 AM
> To: RTEMS Users
> Subject: Locked tasks
> If two tasks have the same priority and one of them goes into a locked
> up state, such as a while loop, will the other task get scheduled again
> if the locked task does not specifically relinquish?  What I believe is
> happening is that my termios task is getting locked out at the write but
> preventing my other task of equal priority to run.
> Is there a way to use timeslices so a task never gets all cpu usage?

I thought that if you are using termios with a polled device, that it
sleeps 1 tick if nothing is available.  Are you using it in interrupt
mode or polled mode?

> --
> Angelo Fraietta
> PO Box 859
> Hamilton NSW 2303
> Home Page
> http://www.users.bigpond.com/angelo_f/
> There are those who seek knowledge for the sake of knowledge - that is
> There are those who seek knowledge to be known by others - that is VANITY
> There are those who seek knowledge in order to serve - that is LOVE
>     Bernard of Clairvaux (1090 - 1153)

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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