Messages in this thread | | | Subject | Re: CPU throttling?? | From | Daniel Egger <> | Date | 04 Feb 2003 15:34:03 +0100 |
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Am Mon, 2003-02-03 um 20.24 schrieb Valdis.Kletnieks@vt.edu:
> I knew that. The question I asked was whether halted at 700Mhz takes more > power than halted at 400Mhz...
PowerPC CPUs will shut down unneeded units. There's no such things as a "hlt" instruction. The natural way to slow down the CPU causing more sparetime to shut down single units is to throttle the dispatching of instructions for which there's are flags in the control register set.
I've no idea where the frequency scaling should happen but it either needs some hardware clock control or it's the mentioned dispatch throttling. In case of the former there'd be some powersave effects because the power drawn by a CPU is direct proportional to the frequency. In the latter case the difference between an automatically sleeping 700Mhz and a throttled 700Mhz cpu at "400Mhz" should be pretty small, in case the cpu is mostly idle.
-- Servus, Daniel [unhandled content-type:application/pgp-signature] | |