cpufreqd as standard install?

[Phillip Susi]

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On 03/05/2012 08:10 PM, Christopher James Halse Rogers wrote:
> To restrict the maximum frequency when on battery / low battery?  The
> last analysis I've seen, by Matthew Garrett, was that the most
> power-efficient way to run modern CPUs is to have them run as fast as
> possible - in order to do the pending work in the shortest possible time
> - then drop down to a low-power C-state.

This is incorrect.  Lower frequency ( coupled with lower voltage ) provides less power per instruction.  You may be confusing some of his writing about the p4clockmod driver, which doesn't actually lower the cpu voltage or frequency, but rather just forces the cpu to HLT as if it were idle for part of the time.  This does not give better efficiency, which is why he patched that driver to refuse to bind to the ondemand governor.

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