Re: Bug#396117: ITP: cpufreq-detect -- detect CPU frequency control driver
Anthony DeRobertis wrote:
> Peter Palfrader wrote:
>
>> How come it never outputs p4_clockmod? I use that happily on several
>> different machines.
>>
>>
>
> I can confirm I've tried it on a machine. The performance impact was
> substantial (at least if I allowed it to go to its lowest speed); the
> power consumption difference was immeasurable[0].
>
> Have you actually measured the power savings?
>
> [0] Immeasurable as in the measurement equipment (an UPS with load
> indication, in this case) could not notice any difference. The same UPS
> does notice a substantial difference with K8 chips.
>
>From what I remember reading on some LKML threads a while ago,
p4-clockmod is not that interesting because it only does throttling
(divides the frequency only) while the important thing to do to reduce
power consumption is to use C-states as other drivers/processors do
(reduce both frequency and voltage).
http://marc.theaimsgroup.com/?l=linux-kernel&m=114072746504710&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=114123706515874&w=2
Brice
Reply to: