Subject: Re: QUESTION: real-time, interrupt latency & atom process
To: Dr. Magnus Sethson <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: tech-kern
Date: 11/13/2001 21:45:55
> Controlling robots and machines using a real-time operating system is
> allways an interesting topic.  [ it's not very
> real-time in this sense...500us-100ms max interrupt latency...]

Short of just using an overmuscled CPU that can do more than you'd ever
want to in one control cycle, there isn't much to do but use another
CPU.  NetBSD has some SMP stuff, but it probably won't be much use to
you, since your task is decidedly *a*symmetric.  Back in the days of
MicroVAX-IIs and 4.3BSD, I built a microkernel to run on a slave CPU in
a uVII.  While I am inclined to doubt this would be of much direct use
to you, some of the lessons learned might be of interest.  (If 4.3 can
do it, NetBSD probably can. :-)

I can put you in touch with the person who did the project (all I did
was write the microkernel to run on the slave CPU), if you want - he's
now a professor at another university.

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