SCOUG-Programming Mailing List Archives

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Date:	Sun, 30 Apr 2000 16:08:42 PST
From:	Peter Skye <pskye@peterskye.com >
Reply-To:	scoug-programming@scoug.com
To:	scoug-programming@scoug.com
Subject:	SCOUG-Programming: OS/2 as real-time OS ?

Content Type: text/plain

Steven Levine wrote:
>
> I've been involved in some aerospace stuff.
> ... The inner loops where invariably analog.

Yup. Analog works!

> The DSP we used was capable of implementing a 50
> block control loop with several filters in 800 uSec.

I sense a topic for a future Programming SIG ...

> Ideally you want to write as much of the application
> as possible in ring 3. This requires context switches.
> My understanding is that the OS/2 scheduler will not
> guarantee a context switch to even the highest
> priority process in much less than [1 msec].

So stay out of ring 3. :)))

If it's to be a "real-time" system, there's no reason why the real-time
portion can't stay in ring 0.

> >Hah, you got me. What is a "context hook"?
>
> You know those DDK books you misplaced...

Me? Misplace something?

> A context hook allows an interrupt handler to schedule
> part of itself to run at task time (i.e. just before the
> scheduler would return control to an interrupted
> process). This code is interruptible, so it can do the
> work it needs without holding off other pending interrupts.

Let me go and review the header code ...

- Peter

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