Re: Two real time tasks?

POSIX priorities are higher number, higher priority.

In the original RTLinux, we used the reverse approach so that 
0 was always highest priority, but POSIX makes more sense.


On Thu, Feb 10, 2005 at 06:39:08PM -0500, Chris Smolinski wrote:
> I did use priorities, and I am not seeing preemption. I am calling 
> pthread_setschedparam() at the beginning of the real time threads 
> with sched_priority in the sched_param set to a higher number for the 
> slower running test. Is this not the correct way to do it?
> 
> >Use priorities so that the faster task can preempt.
> >
> >On Thu, Feb 10, 2005 at 01:47:40PM -0500, Chris Smolinski wrote:
> >> I have a question concerning running two real time tasks at once.
> >> I've created two such tasks, one running every 250 microseconds, and
> >> one every 10 millieconds. For testing purposes, I have each test turn
> >> a parallel port line on when the task starts to run, and off just
> >> before it goes back to sleep. Viewing the two outputs on a scope,
> >> everything looks fine.
> >>
> >> But, if the slower task takes longer than 250 microseconds to run
> >> (actually the problem happens before then), it is not pre-empted to
> >> allow the faster task to run. Instead, once it is done, the faster
> >> task runs, and then the next instance of the faster task runs
> >> earlier, presumably so that the average execution rate remains 250
> >> microseconds.
> >>
> >> Is there anything I can do to have execution of the slower task
> >> halted to allow the faster task to run at the correct time, and then
> >> return to the slower task when the faster task is finished?
> >>
> >> --
> >>
> >> ---
> >> Chris Smolinski
> >> Black Cat Systems
> >> http://www.blackcatsystems.com
> >> _______________________________________________
> >> Rtl mailing list
> > > [email protected]
> >> http://www2.fsmlabs.com/mailman/listinfo/rtl
> >
> >--
> >---------------------------------------------------------
> >Victor Yodaiken
> >Finite State Machine Labs: The RTLinux Company.
> >www.fsmlabs.com  www.rtlinux.com
> >1+ 505 838 9109
> 
> 
> -- 
> 
> ---
> Chris Smolinski
> Black Cat Systems
> http://www.blackcatsystems.com

-- 
---------------------------------------------------------
Victor Yodaiken 
Finite State Machine Labs: The RTLinux Company.
www.fsmlabs.com  www.rtlinux.com
1+ 505 838 9109

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