Subject: Re: QUESTION: real-time, interrupt latency & atom process
To: None <>
From: Peter C. Wallace <>
List: tech-kern
Date: 11/14/2001 18:10:29
	I've been curious about this myself. We have a little PC/104 card
that is a 8 axis host based servo motor controller. For most motors you
need a 3-4 KHz interrupt rate to get good performance (though larger
slower motors can use a slower update rate) This works fine on DOS where
nothing else is really happening, but would this high an interrupt rate be
possible with NetBSD?
	The calculations for 8 axis of simple PID + feed forward +
profile generation take very little time on a 486, but the interrupt
latency is liable to be the problem.

	I guess the rate of lost characters on an unbuffered serial port might
give a clue...

Anyone run an 8250 at 38400 baud?

	If anyone is interested in playing with the hardware, I am willing
to donate motor controller cards (and ISA adapters if needed)

Peter Wallace