Re: [Xenomai] ipipe tracer question

["Stéphane ancelot" <sancelot@numalliance.com>]

   On 03/11/2016 17:38, Henning Schild wrote:

Am Thu, 3 Nov 2016 16:29:08 +0100
schrieb Stéphane ancelot [1]<sancelot@numalliance.com>:


On 03/11/2016 09:36, Henning Schild wrote:

Am Wed, 2 Nov 2016 18:10:48 +0100
schrieb Stéphane ancelot[2]<sancelot@numalliance.com>:



Hi,
I have got an RT task that seems being disturbed by some system
driver.

So, I have setted up ipipe tracer in kernel.


The tracing uses the kernel tracing infrastructure. Use the
sysfs-Interface or a tool like trace-cmd or perf to collect traces.
[3]https://www.kernel.org/doc/Documentation/trace/ftrace.txt



I am now able to trace in the kernel.
I made some function trace in  the shell, but I have not managed to
find where is my problem.
I want to find where my tasks spend more time than usuallly. e.g.
(end task - start task) > 500us

I have some references to cobalt_head_sysentry , cobalt_head_sys
I made a trace with trace-cmd and I am able to load it with
kernelshark. a bit difficult to understand the graph.

I have never worked with kernelshark, usually i read the traces in a
pager or text-editor.
To get a better correlation with the RT task activity and the kernel,
you should leave traces from the application.
Have a look at include/cobalt/trace.h to see functions that help you do
that. Some of them are used in some of the examples, i did not find
documentation, but the names sound kind of meaningful.


   I found some informations in web archives regarding these functions:
   [4]https://mail.gna.org/public/xenomai-core/2006-06/msg00180.html
   I used xntrace_special() in my program, but unfortunately, altough it
   does not reply with ENOSYS error, I can't sea really how it is reported
   in trace log.
   how can I watch the numbered given in parameters.???

It is best if you stop tracing as soon as you detected a violation.

Filter the trace ie with grep after you collected them, the first thing
to read it backwards from the spike filtering by CPU. If you are lucky
you have left a "all good" mark somewhere close above the problem.

If you still have trouble to read it, maybe kernelshark can process
parts of a whole trace. Or you will at least have a better idea where to
zoom in.



But I do not know where to  go  now ?
I suppose being on the right way, but what to do next ?

Regards,
S.Ancelot


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References

   1. mailto:sancelot@numalliance.com
   2. mailto:sancelot@numalliance.com
   3. https://www.kernel.org/doc/Documentation/trace/ftrace.txt
   4. https://mail.gna.org/public/xenomai-core/2006-06/msg00180.html
   5. mailto:Xenomai@xenomai.org
   6. https://xenomai.org/mailman/listinfo/xenomai
   7. mailto:Xenomai@xenomai.org
   8. https://xenomai.org/mailman/listinfo/xenomai