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Re: cpu scaling questions



On Mon, 2006-10-02 at 16:19 -0400, Dave Jones wrote:
> On Mon, Oct 02, 2006 at 03:16:26PM -0500, Jason L Tibbitts III wrote:
>  > >>>>> "DJ" == Dave Jones <davej redhat com> writes:
>  > 
>  > DJ> With p4-clockmod each core is independant, because it's not really
>  > DJ> scaling, it's inserting waitstates in each clock tick per
>  > DJ> 'thread'.
>  > 
>  > Does p4-clockmod actually save any power, reduce heat output or do
>  > anything useful other than making the CPU act slower?
> 
> Allegedly it reduces heat by 'stretching' out a long running
> job over a longer period of time.

It's important to note that the rate of heat production will be lower
this way, but the total heat produced (i.e. actually energy used) during
the lifetime of a given job will be slightly higher.

That is, it doesn't save any power at all, and it produces slightly more
heat in the long run.  But if you've got adequate HVAC you'll *notice*
less of the heat when you're sitting in front of the machine.

I.e. it sucks.

-- 
  Peter


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