Re: CPU power management
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Mattia Dongili wrote:
> On Fri, Feb 16, 2007 at 06:22:29PM +0100, Mattia Dongili wrote:
>> On Thu, Feb 15, 2007 at 11:26:24PM +0200, Eddy Petri??or wrote:
>>> I have installed Debian GNU/kFreeBSD and indeed, the levels are many
>>> more than on Linux:
>>> sysctl dev.cpu.0.freq_levels
>>> Results in a list of frequencies down to 31 MHz. I tried some script I
>>> found on the freebsd lists to test the speed of blowfish at various
>>> speeds and observed that on my Core 2 Duo that:
>>> In conclusion, it would be nice if this code would be ported to Linux, too.
>> AFAICT they are mixing freq scaling and throttling.
>> See /proc/acpi/processor/CPU/throttling, I have:
Is that on Linux or kFreeBSD?
>> state count: 8
>> active state: T0
>> *T0: 00%
>> T1: 12%
>> T2: 25%
>> T3: 37%
>> T4: 50%
>> T5: 62%
>> T6: 75%
>> T7: 87%
>> and the available frequency steps here are 1.83 GHz, 1.33 GHz, 1000 MHz
>> This is a Core2 Duo T5600.
>> so eg. at 1GHz I can throttle at 880, 750, 630, 500, 380, 250 and
>> 130 MHz.
> Oh, and let me add (even if probably aready mentioned): throttling
> doesn't save any power, it just idles your cpu. Ok, less heat (no fans,
> etc) but the real saving is probably unnoticeable.
Taking into account that my laptop almost all the time heats up even
if scaled down to 50% (1GHz/minimum) in Linux, thus triggering
periodic fan runs at regular intervals, which, of course, leads to
more power consumption, I'd welcome throttling .... although I don't
know if it would make any difference taking into account my laptop
always runs at 1GHz when on battery.
"Imagination is more important than knowledge" A.Einstein
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