[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: CPU power management

Hash: SHA1

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[1] 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[01]/throttling, I have:

Is that on Linux or kFreeBSD?

>> state count:             8
>> active state:            T0
>> states:
>>    *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
Version: GnuPG v1.4.6 (GNU/Linux)


Reply to: