On Mon, Dec 15, 2014 at 03:11:45PM +0000, Stoidner, Christoph wrote:
>
> >> >> > it seems to me as APC interrupts on ipipe got lost. I have added two
> >> >> > counters:
> >> >> > One increments in schedule_linux_call() when a request for a specific
> >> >> > application
> >> >> > task is queued. Another one is incremented in lostage_handler() when
> >> >> > the
> >> >> > specific task was waked up. When I output the counter's values after
> >> >> > tasks have
> >> >> > freezed the counter of lostage_handler is exactly one value less than
> >> >> > schedule_linux_call's counter.
> >> >> >
> >> >> > And then, when I wake-up APC thread manually all freezed tasks
> >> >> > continue for a
> >> >> > moment, until all are freezing again.
> >> >>
> >> >> As said above waking APC thread using
> >> >>
> >> >> wake_up_process(rthal_apc_servers[smp_processor_id()]);
> >> >>
> >> >> does reactivate all Xenomai threads for scheduling. Incontrast using
> >> >>
> >> >> rthal_apc_schedule(lostage_apc);
> >> >>
> >> >> does not help. So it seems as APC interrupt is pending but won't be
> >> >> executed.
> >> >>
> >> >> Any idea?
> >> >
> >> > Do you have the same issue if you run a kernel patched with Xenomai
> >> > and without the PREEMPT_RT patch?
> >>
> >> No, without PREEMPT_RT the problem did not yet occur.
> >
> > Have you tried to follow the path from rthal_apc_schedule to
> > rthal_apc_handler to see where the notification gets lost?
>
> I am about to do that. Unfortunately I am not very familiar with ipipe
> implementation. Do you know if there are some tracing or debug
> features that could help me here?
The APC code mostly happens in ksrc/arch/generic/hal.c and the
PREEMPT_RT path is distinct from the non PREEMPT_RT one, so, I would
tend to believe that the problem is in that code. As for tracing,
same as usual, you can use the I-pipe tracer, injecting some calls
to ipipe_trace_special() perhaps, to save some values in the trace.
--
Gilles.
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