Hello Karim,
planning the exact load on this system is quite difficult because its
behaviour is very dynamic:
- the realtime control module is basically a softplc system which is
configured through an Oracle
database at startup, so everything it is doing depends on its
configuration. The more logic operations,
functions and IO you configure the slower it gets (and sometimes my code
needs some optimizations
too, yesterday I had a quite simple configuration which took 890 us to
complete, now its 110 us after
some optimizations :)
- we have a user on this system who is running an X application with an
Oracle connection and 2 serial
links to some other hardware which is not controlled by my system. This
applications also recevices
values from my realtime module via FIFO each time a value, either
calculated or IO, changes.
- the system is a diskless station, so everything gets loaded via NFS from
the bootserver.
The size of my module in RAM is now about 800k, but I will do a little
downsizing of my data areas,
because the recent process doesnt need them to be this big, but other
machine controls may need
some more (the machine I'm controlling now is pretty simple).
The worst cases I got so far is an additional time of about 240 us, this
happened when running my
development environment (KDevelop) on an X Client and doing a rebuild all.
If its not getting worse than
this then I can live with it.
Marco
> -----Urspr�ngliche Nachricht-----
> Von: Karim Yaghmour [SMTP:[EMAIL PROTECTED]]
> Gesendet am: Mittwoch, 20. September 2000 19:18
> An: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Betreff: Re: [rtl] Execution time of Realtime-Task
>
>
> Hello Marco,
>
> Off the top of my head the following comes to mind:
>
> Real-time systems "assume" a controlled environment. When you use the
> network,
> the network card starts firing off interrupts and the system, real-time or
> not,
> has to handle those. Now, in a real-life case, you would have planned
> exactly
> what type of load these interrupts can have on your system and would have
> planned
> the task scheduling and hardware structure accordingly. This isn't the
> case
> right now as you have a "user" involved ... and that's lots of
> underterministic
> behavior in most books ;)
>
> I might be off a little, but I think this is part of your answer ...
>
> Best regards
>
> Karim
>
> [EMAIL PROTECTED] wrote:
> >
> > Hello everybody,
> >
> > my Realtime application is now in a state where I can say it is working,
> > and its working very well so far :)
> >
> > What I noticed during my tests is that sometimes my realtime tasks takes
> > very different times to complete, with a minimum of about 110
> microseconds
> > and a maximum of about 350 microseconds.
> >
> > This task is running at 1kHz, reading and writing 2x16 bits of IO from 2
> > DIO-Boards
> > and then executing some functions. The problem is, its is doing EXCACTLY
> the
> >
> > same things as long as the IO-signals dont change ... so theoretically
> it
> > should
> > always have the same execution time ......
> >
> > There is no other RT Task which could interrupt it, and no interrupts
> are
> > used in
> > my module.
> >
> > I'm runnning my app on a diskless station, 500MHz Celeron, 128 MB RAM,
> Intel
> > EEPro,
> > RTAI 1.4 with Kernel 2.2.16. XWindows is running at 1024x768, and I am
> also
> > connected
> > with an X-Terminal on Windows NT.
> >
> > So my question is: what could influence my Realtime task so that its
> > execution time differs
> > from time to time ? I noticed execution time going up when I have X
> running
> > and when
> > I am running applications from my X-Server on NT.
> >
> > Any ideas anybody (and maybe a solution :) ?
> >
> > Thanks in advance,
> >
> > Marco Schwarz.
> >
> > -- [rtl] ---
> > To unsubscribe:
> > echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
> > echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
> > ---
> > For more information on Real-Time Linux see:
> > http://www.rtlinux.org/rtlinux/
>
> --
> ===================================================
> Karim Yaghmour
> [EMAIL PROTECTED]
> Operating System Consultant
> (Linux kernel, real-time and distributed systems)
> ===================================================
-- [rtl] ---
To unsubscribe:
echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
---
For more information on Real-Time Linux see:
http://www.rtlinux.org/rtlinux/
