# cpufreq scaling doesn't work [reclosed]

## hug0

Hi, my cpufreq-info keeps saying:

```

hardware limits: 1000 MHz - 2.00 GHz

available frequency steps: 2.00 GHz, 1.67 GHz, 1.33 GHz, 1000 MHz

current policy: frequency should be within 1000 MHz and 1000 MHz.

```

The problem is, that I am not able to change the value of

/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

Suprisingly, it is working sometimes after a boot, but every time I plug / deplug the AC, it falls back to 1000.

It seems to be gentoo related - On Knoppix 5.1 everything is working normal.

What I also discovered is, that everytime I plug the AC in, it is showing the correct 2000MHz upper frequenz - but only for a few seconds!

I tried a lot in the BIOS - without success. And Knoppix is the proof that my BIOS settings are fine.

I found a lot of people with the same or at least similar problems on the web, but no solution.

Some more infos about my system:

Thinkpad T60, kernel 2.6.20-suspend2-r6 or 2.6.19-r5

Thanks for any hints!

FlorianLast edited by hug0 on Mon Aug 06, 2007 10:14 am; edited 3 times in total

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## magowiz

You should check that theese options are enabled in your kernel under frequency scaling :

-CPU_FREQ

-at least one of the governors

-the appropriate driver for your cpu in frequency scaling

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## hug0

These points are ok!

I realized that it is working fine after a boot untill I change the powermode (plug in AC, remove AC...).

So my basic settings seems to be fine!

EDIT:

Ok. It is working for about 5 minutes, then it is back to 1000MHz  :Sad: 

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## hug0

Ok, at least I figured out, where the few seconds with full speed come from:

while plugging AC in or out:

```

processor CPU0 00000080 00000000

processor CPU1 00000080 00000000

// now I have 2GHz

// few seconds later:

processor CPU0 00000080 00000003

processor CPU1 00000080 00000003

//now I am back on 1GHz

```

 :Rolling Eyes: 

Florian

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## Sachankara

 *hug0 wrote:*   

> Ok, at least I figured out, where the few seconds with full speed come from:
> 
> while plugging AC in or out:
> 
> ```
> ...

 You could always make sure that cpufreqd is not activated. You don't need it as the kernel does a good job itself managing the cpu. Also, make sure you've activated HPET timers in the kernel.

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## hug0

I think I got it:

Indeed it was a BIOS setting, but not the CPU-frequency stuff, but the Thermal Managment which wasn't set to max.

(cpufreqd is off and kernel timer settings are enabled)

Thanks! Florian

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## hug0

New Problem:

After a BIOS Update (now 2.16 on a Thinkpad T60), my CPU is slowing down again if I remove the Battery.

Any ideas?

Florian

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## zigver

Check your bios again.  I don't recall which version I'm running but I know there is a separate thermal management setting for both the AC and Battery so maybe double check these settings.

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## hug0

Yup, I know.

The thing is, it is not the difference bewteen "AC" and "Battery" but between "AC with battery pluged in" and "AC without battery pluged in" which causes the cpu scaling freeze...

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## hug0

Got it. I have to powersupplies. The small one (60W) seems to force the BIOS to reduce the cpu speed...

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