Re: An important fact about real time computing

From: yodaiken@fsmlabs.com
Date: Wed Jul 19 2000 - 15:38:32 EST


On Wed, Jul 19, 2000 at 03:47:01PM -0400, David Mansfield wrote:
> David Balazic wrote:
> >
> > The first sentence my professor maid on the real time computing
> > course was :
> >
> > "A common misconception : Real-time computing is fast computing."

This is the standard lecture, but don't take it too far. You can control
a robot with deterministic latecnies under 50 usecs, but not with
deterministic latencies of 10 minutes.

> To summarize, I agree that the 'audio people' have a real-time
> requirement. I claim that the kernel already has real-time
> requirements. I also claim that any real-time system is only a
> probability curve of making the deadline, and that the 'audio people'
> only want to shift this curve to make the deadlines they are looking for
> fall into the probability of failure they find acceptible.

You understate the difficulties by using this form of argument. I'd
like my 1992 V4 Ford Ranger Pickup to fly at Mach 3 at 35,000 feet.
The truck already leaves the ground for short periods
if I drive over bumps. So it already has an aircraft requirement and
I only want to shift the flight curve to a level I find acceptable.
Should be simple, no?

-- 
---------------------------------------------------------
Victor Yodaiken 
FSMLabs:  www.fsmlabs.com  www.rtlinux.com
FSMLabs is a servicemark and a service of 
VJY Associates L.L.C, New Mexico.

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