HOWTO: CPU Frequency Scaling w/ Kernel Module

[ptitpoul]

With Feisty Fawn (updated from edgy), step 6 (Add modules in /etc/modules) is not necessary, at least on my PC (amd athlon 64 with powernow-k8). So, pharcyde, maybe you should precise for which release it's necessary.

[fidolip]

Hi!

I tried to follow your HOWTO and everything seemed to be alright, but when I restarted my computer I got a message:

CPU frequency scaling unsupported
You will not be able to modify the frequency of your machine. Your machine might be misconfigured or not have hardware support for CPU frequency scaling.

and now my CPU freq is always on it's maximum. Could someone help me with either changing it back to how it used to be or fixing this problem?

Processor is Intel Centrino and I have dapper drake.

[Joriz]

Hi

thanks for a wonderfull howto, mi problem is that when I restart the computer it seems like it somehow doest remember this settings, and I need to run all the commands again.
And I am not using a live cd...

Anybody has an idea about how to solve this?

I have the same problem here hmz

Nevermind, i placed something wrong in modules.conf hehe, works fine now, nice tutorial

[cdeel77]

Thanks for the great HOWTO!

I tried doing this with my Pentium 4 (1.4 GHz; family 15 model 0 stepping 7) running Edgy Server.

I used the "p4_clockmod" module. I checked the CPU freq with 3 methods:

cat /proc/cpuinfo
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
cpufreq-info

Before loading module, freq was 1406.274 (seems normal, right?)
After loading module, was 2200.000

Is my CPU really running at 2.2 GHz? If so, that could be a bad (overheating) thing, right? And how did that happen?

Output of cpufreq-info:

analyzing CPU 0:
  driver: p4-clockmod
  CPUs which need to switch frequency at the same time: 0
  hardware limits: 550 MHz - 2.20 GHz
  available frequency steps: 550 MHz, 825 MHz, 1.10 GHz, 1.38 GHz, 1.65 GHz, 1.93 GHz, 2.20 GHz
  available cpufreq governors: performance
  current policy: frequency should be within 550 MHz and 2.20 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 2.20 GHz.

Should I just use "cpufreq-set --max 1375000" to limit the top speed, or do I have an unusual problem?

I've also tried loading the generic "acpi-cpufreq" module, but I get "FATAL: Error inserting acpi_cpufreq (/lib/modules/2.6.17-11-server/kernel/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.ko): No such device"

Thanks for any help/advice! (Just trying to reduce power consumption/heat buildup on my lightly-used home server. I intend to use "ondemand" governor.)

[jbmech006]

I posted earlier in this forum about a problem I was having after I followed the steps listed in the howto. Basically my CPU scaling was unsupported after I rebooted and was locked at 1.83ghz (I have an Intel Core Duo processor). To fix the problem I installed the powernowd package from synaptic package manager. Rebooted Gnome (Ctrl-Alt-Backspace) and now my CPU scaling support is working again. I hope this helps people with a similar problem.

[bobreeves]

Thanks for this most helpful post. I screwed around for days trying to get powernowd or cpudyn working with absolutely no success.

With your tutorial, I now have CPU scaling functioning on my Toshiba Satellite, and running in demand mode. I am running a Parsix distro (Knoppix based), and knew that CPU scaling should work, as it worked by default in Ubuntu.

Great job!

Bob Reeves

[Adahn]

when I attempt to 'sudo modprobe powernow-k8' I get this error:

FATAL: Error inserting powernow_k8 (/lib/modules/2.6.20-15-generic/kernel/arch/x86_64/kernel/cpufreq/powernow-k8.ko): No such device

I get a similar error with modprobe acpi-cpufreq

this: cpufreq-info
gets me this: no or unknown cpufreq driver is active on this CPU

anyideas?

I'm running a mobile athlon64 in a desktop board. Scaling works fine in windows.

tony@tony-desktop:~$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 36
model name : Mobile AMD Athlon(tm) 64 Processor 3400+
stepping : 2
cpu MHz : 910.719
cache size : 1024 KB
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt lm 3dnowext 3dnow up pni lahf_lm
bogomips : 1822.84
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

[aerowinged]

I followed this tutorial,
But when i got to part my CPU0 does not have the directory. So instead i just finished the tutorial with CPU1. But when i restarted the computer, i still got the "CPU Scaling unsupported" message.
Could it not be working because i am missing this directory from my CPU0 folder. Where can i get the necessary files to replace it?

I also tried this:
I installed cpufreqd. And in the details this is what i got. (just the last 2 lines)

:Setting up cpufreqd 2.2.1-2 ...
No cpufreq interface installed, not starting cpufreqd

So then i installed powernowd which automatically uninstalled cpufreqd. And this is was it said at the end of the details

* Starting powernowd...
/etc/init.d/powernowd: 156: cannot create /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor: Directory nonexistent
* CPU frequency scaling not supported
...done.

So i think that this missing directory i have in CPU0 in the cause of the whole problem. What can i do!? CPU Scaling works fine in windows, so i know its not my hardware.



Here are the details of my processor:

processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz
stepping : 6
cpu MHz : 1828.859
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
bogomips : 3661.16
clflush size : 64

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz
stepping : 6
cpu MHz : 1828.859
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 1
cpu cores : 2
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
bogomips : 3657.81
clflush size : 64

Please help me! thanks guys

[kaar3l]

My T5600 works out of box, on 1000mhz and 1800mhz. i use kubuntu

[matburton]

Hey,

I'm using Feisty and want to set my governor to conservative at boot. But everything I try doesn't seem to work.

I made a script that runs with run level 2 that did either

sudo cpufreq-selector -g conservative

or

echo conservative > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

But both didn't work and swapping from run level 2, down to 1 and back up to 2 showed that the governor was just set back to ondemand whatever it was previously.

Then I tried installing and using sysfsutils by changing /etc/sysfs.conf but that had no effect either.

Is Feisty different?
How do I set the default governor in feisty?

Thanks, Mat

Edit:
I fixed my problem. I had a look at how powernowd starts in /etc/init.d and edited the script slightly to always set the governor to conservative.
I quick sudo /etc/init.d/powernowd restart confirmed that this worked