Re: [Xenomai-core] My work on Xenomai integration to LTTng / LTTV

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

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Jean-Olivier Villemure wrote:
> Hello,
> 
> I'm currently working on the integration of Xenomai tracing in LTTng
> (Linux Trace Toolkit Next Generation) and the event viewing in LTTV
> (Linux Trace Toolkit Viewer).
> 
> At this moment, I 'm tracing events about task handling, period and
> soon, mutex and semaphore synchronization.

Wow, great news!

> 
> Inserting traqcing points in Xenomai nucleus is not very difficult, my
> main work is focus on the controlflow viewer module of LTTV. At this
> moment, we can open a trace and view:
> - Task state : init, started, running, suspended, overrunning (period
> miss)
> - Period timer tick for periodic task
> - Textual information about the task (name, period, priority, birth)
> - Mutex/semaphore owned by specific task
> - Soon task waiting on mutex/semaphore
> 
> Look at the screenshot to have a better idea.
> 
> The next step will be to generate some statistics, for this step I will
> need your help. As Xenomai users, which kind of stats would you want to
> compute?

 - CPU usage (see /proc/xenomai/stat for average numbers, but we should
   now be able to precisely calculate them for a specific period)
 - Waiting times after activation (maybe one can define deadlines later
   and verify them)
 - Number of preemptions per second or whatever while a task is runnable
 - Number of blockades a task faces due to unavailable resources
   (mutexes, semaphores, etc.)

...just to through some first ideas in.

> 
> After that, I'll study the possibilities of simulating an execution
> trace from an existing trace by modifying some parameters (period
> length, ...)
> 
> Any ideas are welcome!

So you have an integrated I-pipe+LTTng patch which is able to record
events under any context and push them to Linux non-RT user-space,
right? How does this work, what impact does it have (also compared to
the I-pipe tracer, which is not light-weight)? And, most important, when
will we be able to see some code (ipipe add-on patch)? Would be good to
assess how this could be integrated on the long term into
I-pipe/Xenomai, at least until required LTTng parts become mainstream.

Jan


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