On Thu, 2007-03-08 at 11:08 +0100, Steven Scholz wrote:
> Philippe,
> 
> >> using an oscilloscope I found that the AT91RM9200 spends up to 300┬Ás in the
> >> interrupt handler for ethernet controller.
> >>
> >> Now I wonder if this interrupt handler will be preempted by Xenomai if 
> >> there
> >> is a high priority, periodic real time task?
> > 
> > Hw interrupts are forcibly enabled before entering any Linux IRQ
> > handler, exactely to prevent the issue you described (e.g. fiddling with
> > an IDE controller in PIO mode also gives funky latency results unless
> > the latter is true), so the answer is yes.
> Thanks.
> 
> >>  Thus will the duration of the
> >> ethernet interrupt handler add the the worst case latency?
> > 
> > Not from Linux IRQ handlers; you may want to check this using the
> > tracer. If hw interrupts are masked there, then it's a blatant bug.
> 
> How could I check this using the tracer? Small hint please?

http://www.xenomai.org/index.php/I-pipe:Tracer

> 
> Steven
-- 
Philippe.



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