Re: Simulating slower processor.

From: Richard B. Johnson (root@chaos.analogic.com)
Date: Tue May 02 2000 - 13:00:06 EST


On Tue, 2 May 2000, Krisztian Flautner wrote:

>
> Does anyone have any suggestions on how I could simulate a slower
> clock speed on my machine without actually changing the crystal?
> I would like to make my machine seem like a 45Mhz machine instead
> of the 450Mhz machine it actually is. The simulation does not
> need to be perfect, I would just like the first order effects
> (i.e. slower execution time). I would like this to work on SMP
> machines as well...
>
> I guess what is required involves changing the default time slice
> and forcing the scheduler to wait for a certain time after running
> each task. My concern is that it would really screw up timing
> critical parts.
>
> What are your suggestions, is this doable or should I just hack
> the box to run at a slower speed? Has anyone done this before?
>

Make a driver on IRQ7 (the printer port). It contains just an ISR.
The ISR just wastes some time (you can make it variable with an
ioctl()), then returns.

Connect a function generator to your printer port, + 5V, 50 to 50 kHz.
The faster you interrupt, the slower your PC.

Cheers,
Dick Johnson

Penguin : Linux version 2.3.41 on an i686 machine (800.63 BogoMips).

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