Jan Kiszka wrote:
> Gregory CLEMENT wrote:
> > Here, they are the last latency we get on AT91SAM9261-EK. As just now
> > I haven't the board at home, I send the last result we stored. The
> > prority of dbgu should be set to 6 instead of 7, but I can't assure
> > it, for Xenomai.
>
> Hmm, hardware interrupt priorities must not impact the worst-case
> latency if I-pipe acks and mask them appropriately (the worst case is
> when multiple interrupts happen in a row, not at the same time). But
> this statement is not based on knowledge about potential pitfalls of
> this arch. Are there specialities that require this tweaking?
During the port to AT91RM9200, I observed that under ping flood, the
ethernet driver interrupt was delaying the timer interrupt for unbounded
period of times, this because it had a higher priority. Changing the
interrupt priorities solved the issue. That said, I understand what you
mean, the interrupt should be masked when acked and should no longer
bother us until the I-pipe gives control to Linux to handle it.
>
> > first Xenomai:
> >
> > #insmod
> > /lib/modules/2.6.20.13/kernel/drivers/xenomai/testing/xeno_timerbench.ko
> > #cd /usr/xenomai/bin/
>
> Which versions were you using for both tests? Do you still have the
> involved .configs?
>
> > #./latency -t 2 -p 150 -h -H 500
Why not -p 500 ? Since RTAI was tested with a 500 us period, the same
period should be use for Xenomai. I do not think this will change
anything, but who knows.
--
Gilles Chanteperdrix.
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