CPU Frequency Scaling

Erik Trulsson ertr1013 at student.uu.se
Sun Mar 9 12:02:39 UTC 2008

On Sun, Mar 09, 2008 at 01:28:17PM +0200, Marcel Cuculici wrote:
> Hello everyone! My system hardware is Asus P5B with Intel Core Duo 2 e6600.
> I installed on it freeBSD 7.0 Release yesterday, but I don`t understand
> something. In Gnome there is CPU Frequency Scaling Monitor Witch it`s set to
> Performance, and the Cpu freq. is 2.39 Ghz, I can change it MANUALLY to
> other freq as can bee see it in the link`s above, but can not set to Economy
> :|
>  In bios I have Intel Speed Step Enabled, and Cpu Freq set to AUTO.
>  However, in Windows XP, my power scheme is set to Minimal Power Management
> And the cpu freq stay at 1.58-1.60, and when computer need more cpu power
> it  AUTOMATICALY jump`s to 2.40 Ghz.
>  The same thing happen`s in Ubuntu linux 7.10 and Debian Etch, the Cpu stay
> at ~1.60 Ghz and it jump`s auto when more Cpu resources is needed.
>  I don`t undersntand why in linux and windows the cpu is automatically
> controlled by operating system and in freeBSD I need to set it manually. How
> can be this changed for freeBSD, to act as windows/linux at cpu freq scaling
> chapter?

You can have it done automatically on FreeBSD too.

First you need to have 'device cpufreq' in your kernel config or load the cpufreq
kernel module with "kldload cpufreq".  If you can change the frequency
manually, then this is probably already done.

Then you need to run the powerd(8) daemon.  It can be enabled to start
automatically at boot time by putting the line 'powerd_enable="YES"' in

<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se

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