Re: [Xenomai-core] xenomai preempting interrupt handler ?

[Philippe Gerum <rpm@xenomai.org>]

On Thu, 2007-03-08 at 12:49 +0100, Steven Scholz wrote:
> Philippe,
> 
> >>>>  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
> 
> "Traces can be generated in many ways. One happens automatically when
> CONFIG_IPIPE_TRACE_IRQSOFF is enabled."
> 
> What exactly does that mean? That one trace is generated during boot?
> 

That means that several sources of trace points exist, one of them being
controlled by the IRQSOFF switch. MCOUNT cause a trace to be emitted
upon each function entry, and so on.

> "Another way is to invoke the testsuite, namely latency or irqbench with the
> option -f to trigger a freeze on each new maximum latency."
> 
> What exactly does "trigger a freeze" mean?
> 

A snapshot of the current trace log, kept from being overwritten in a
separate memory upon freeze, that you can access
through /proc/ipipe/trace/frozen.

> Steven
> 
-- 
Philippe.