[X-Unix] limit cpu usage

[Dan Frakes]

"William H. Magill" <magill at mcgillsociety.org> wrote:
>> But don't processors designed for laptops usually implement some kind
>> of "low power" mode that runs the processor at a reduced clock speed
>> to conserve power and reduce heat? It would make a lot more sense to
>> implement some kernal extension that would simply "down shift" the
>> processor when running tasks with a lower priority.
[snip]
>
> The change in the clock speed of the CPU is implemented in the
> hardware, not software

I think it's more accurate to say that this feature requires that the
hardware support it, but is controlled by a combination of software and
hardware. For example, on Macs (PowerBooks, iBooks, and G5-based desktops)
the hardware supports reduced processor mode or slewing but this feature is
not independent of software. (You can actually disable it in Energy Saver or
using the CHUD tools.)