How can I load a cpu a certain percentage?

I have to simulate load on a computer. Ideally what I would like to do is be able to manipulate the load on the computer, ie load it to like 20% per instance running. Or be able to vary it within the code.

So far my approach has been to create an infinite loop that will load the cpu to 100% and then introduce a variable pause, but I have found this difficule to achieve.

The code is roughly

//infinite loop
usleep(100);

Also I would like to be able to do the same sort of loading with the disk, which I have something that will write a series of numbers then read them again, then proceed to rewrite them.

Neither of these have worked for me, any pointers in the right dircection.

Thanks,
Nick

So you want to falsify the system monitor metrics.... Why?

I would rather not falsify it, but use system resources doing useless tasks.

It would be in order to test how an app performs with limited resources, ie does it hang, crash, or just degrade in performance.

Basically, this right?
http://msdn.microsoft.com/msdnmag/is...l/default.aspx

Yeah its pretty much like that.