Reserving System Resources

[spaz]

So this may be the wrong section of the forum so I apologize now, but it seems to be a more software oriented question then hardware. Is there a way to either shutdown or reserve system resources? I know you can reserve memory in RAM. But what I'm not sure of is it possible to reserve a known number cycles on the processor? Or even better (but not sure if it's possible) can you reserve an entire core of a machine and monopolize it for one application, and force the os to use a different core? (IE leave the OS up and allow system calls/window manager running on a different core?) And I'm not picky about the OS (I prefer linux, but windows is good to)

In terms of progress on this question has not been very satisfactory. I could make the process a really high priority to keep it using most of a core, but the program will not always be using 100% of the CPU so a normal thread scheduler will allow other things back on the core.

I'm not sure if this is at all possible but I'm hoping but googling thus far has not revealed any answers. Thanks for the time in reading this...