On Fri, 2007-02-23 at 14:50 +0100, Steven Scholz wrote:
> Gilles,
>
> >> I am running 2.6.19 + adeos-ipipe-2.6.19-arm-1.6-02.patch +
> >> xenomai-svn-2007-02-22
> >> on an AT91RM9200 (160MHz/80MHz).
> >>
> >> When starting "latency -p 200" it runs for a while printing
> >>
> >> RTT| 00:05:37 (periodic user-mode task, 200 us period, priority 99)
> >> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat
> >> worst
> >> RTD| 11.200| 139.200| 236.800| 1| 10.800|
> >> 280.800
> >>
> >> but then hangs. The timer LED stops blinking. No "soft lockup detected"
> >> appears.
> >
> > The only explanation I have is that the period is too small. I do not
> > observe the same behaviour with latency -p 1000. Note that setting the
> > period to a value comparable to the latency is not considered a normal
> > use of Xenomai.
>
> Sure but I would still not expect the system to hang!
> As I said missing a deadline is bad but ok.
> But hanging the whole system is not quite ok.
>
> >> Using a BDI200 it looks like that in kernel/sched.c:schedule() he is
> >> returning
> >> in the lines
> >>
> >> #ifdef CONFIG_IPIPE
> >> if (unlikely(!ipipe_root_domain_p))
> >> return;
> >> #endif /* CONFIG_IPIPE */
> >>
> >> When stepping trough I only see him getting into schedule() but leaving
> >> it in the above lines and in
> >> include/linux/proc_fs.h:proc_net_fops_create() ...
> >
> > Ok. Thanks for pointing this out. That is interesting, but not very
> > informative. It would be interesting if you could get the full
> > backtrace. What would be also interesting would be to set a break point
> > on the timer interrupt handler and to follow what happens from timer
> > interrupt to timer interrupt.
>
> I tried! Attached the patch I used. Since teh scheduler hangs I can't use
> normal printk(), right?
>
> *ipipe_current_domain != ipipe_root_domain !
> *ipipe_current_domain = c01fc2c0
> *ipipe_root_domain = c01af2c0
>
> But I don't get the output of __backtrace()!
Before calling your backtrace helper, try adding:
ipipe_set_printk_sync(ipipe_current_domain);
>
> my_printk() works with __backtrace(). The dump of a soft lockup works.
>
>
> Steven
>
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--
Philippe.
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