Centrino CPU Frequency Scaling

solotrekker · 04-22-2007, 12:23 AM

Hi all,

I have Centrino 1.6GHz on a Thinkpad R51. When running with Windows, the frequency can reach the lowest point @ 221MHz, and the fan barely spins.

How can I reach the same frequency with OpenSuSE 10.2? I tried the YaST powersave module. But the lowest frequency could only down to 600MHz.

Many thanks!

hollywoodb · 04-26-2007, 07:25 PM

To see what frequencies are available:

Code:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

My Centrino 1.8GHz also goes as low as 600MHz, no lower. May be a limitation in the cpufreq code. When I tried FreeBSD, after a lot of fuss I got it down to 200MHz, which was nearly unusable.

I'm not sure that you can go lower, but you can edit the values in the files in /sys/devices/system/cpu/cpu0/cpufreq/ (be careful)

solotrekker · 04-27-2007, 10:49 PM

Hi,

I tried to edit the files 'cpuinfo_min_freq' and 'scaling_min_freq' under /sys/devices/system/cpu/cpu0/cpufreq with echo command:

Code:

echo 300000 > cpuinfo_min_freq

and

Code:

echo 300000 > scaling_min_freq

But it seems doesn't work. The 'cat' replies the value remains at 600000.

How could I edit those two files?

hollywoodb · 04-28-2007, 11:49 AM

You probably just can't. It might be part of the cpufreq code.

cpufreq has its own mailing list you could try, they'd definitely be the most knowledgeable:

http://www.kernel.org/pub/linux/util...q/cpufreq.html

solotrekker · 04-30-2007, 05:28 PM

Howdy,

Thanks for your reply and the link you gave to me!

You are right.I think the lowest frequency on this chip is 600MHz. Yesterday I put on NHC in Windows. The report showed the lowest frequency was 600, no less. But the funny part was that when I went to the "Properties" from "My Computer", the Windows showed me 221MHz only, which was less than half of the real frequency. duno why...