Re: [Xenomai-core] measuring tasks execution time

[Jan Kiszka <jan.kiszka@domain.hid>]

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Daniel Simon wrote:
> On Wed, 11 Jul 2007 23:20:47 +0200
> Jan Kiszka <jan.kiszka@domain.hid> wrote:
> 
>> I've merge you changes (whitespaces...)
> sorry for bad formatting, my dev. tool is emacs, which sometimes refuse to
> understand tabs...
> 
>> http://www.rts.uni-hannover.de/rtaddon/patches/xenomai/enhance-thread-stats-v2.patch
> 
> this patch seems ok:
> -patched against release 2764 (with 2 self-corrected hunks), compiled on a
> 2.6.20 kernel and test on a P3/UP
> 
>  -my former basic tests (2 periodic tasks providing remote or self
> exectime probing) still give consistent measures (exectime.c in attachment)

Nice to hear.

> 
> -I am thinking about more demanding tests, with intertasks preemption and
> overloads, but in that case the problem is how to assess the measurements?
> Logic analyzer? Be care also with rt_timer_spin, which is not busy-sleeping for
> all the specified time when it is preempted...

You could play with the I-pipe tracer
(http://xenomai.org/index.php/I-pipe:Tracer). If you disable function
tracing (CONFIG_IPIPE_TRACE_MCOUNT), you will be left with far less
overwhelming data, specifically with the instrumentation points on every
Xenomai context switch. That should allow some estimation of the thread
execution times (minus noise due to the IRQs). And then there is highly
experimental LTTng, but it's... well, highly experimental.

Jan


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