A remark to rt_task_make_periodic in lxrt (bug report !?)

andreas.spieker at daimlerchrysler.com andreas.spieker at daimlerchrysler.com
Fri Aug 23 16:36:17 CEST 2002


Hello, 

I had serious trouble with rtai/lxrt for months -
a system with 5-10 processes in userspace,
comunicating with systemV IPC (sem, shm, msq).
I use rtai/lxrt mainly to schedule the processes
which are running with periods of 5/20/40 ms,
some are running aperiodic.

I had freezes (20-60 seconds) during the startup of my processes
and also freezes when restarting a process.
I had the problems on uniprocessor and SMP machines,
on a very slow old toshiba laptop, the freezes had a duration 
of about 1 hour. But when this freezes had finished, the system
ran fine.

In order to find the error I even tried the LTT (fine).
An then, a few days ago, while trying to understand 
the system behaviour with the LLT visualizer 
(but even the LTT data was corrupted/data loss with a warning 
from the collecting LTT module)
and I couldn't find the reason from the trace data --
I understood that the problem was due to a starting time to
    rt_task_make_periodic(...)
lying a few seconds in the past.

After two hours of work, the error was fixed and I had 
no more problems until now. I'm happy with rtai/lxrt.

So I'd like to ask the developers, if they could prevent 
other users from making the same experience.

Greetings, Andreas

-----------------------------------------------------
Dr.-Ing. Andreas Spieker
Research Information and Communication
Assisting Systems (RIC/AA)

DaimlerChrysler AG
HPC T728
D-70546 Stuttgart
Telefon: (+49) 711-17-41434
Telefax: (+49) 711-17-47054 
email: andreas.spieker at daimlerchrysler.com
Besucheranschrift:
Hedelfinger Straße 4 / 6
Esslingen
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