31

I'm trying to change the cpu frequency on my laptop (running Linux), and not having any success.
Here are some details: 

# uname -a
Linux yoga 3.12.21-gentoo-r1 #4 SMP Thu Jul 10 17:32:31 HKT 2014 x86_64 Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz GenuineIntel GNU/Linux

# cpufreq-info
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 2.60 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 2.60 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 2.42 GHz (asserted by call to hardware).
(similar information for cpus 1, 2 and 3)

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
performance powersave

I initially had the userspace governor built into the kernel, but then I also tried building it as a module (with the same results); it was loaded while running the above commands (and I couldn't find any system messages when loading it):

# lsmod
Module                  Size  Used by
cpufreq_userspace       1525  0
(some other modules)

And here are the commands I tried for changing the frequency:

# cpufreq-set -f 800MHz
Error setting new values. Common errors:
- Do you have proper administration rights? (super-user?)
- Is the governor you requested available and modprobed?
- Trying to set an invalid policy?
- Trying to set a specific frequency, but userspace governor is not available,
   for example because of hardware which cannot be set to a specific frequency
   or because the userspace governor isn't loaded?

# cpufreq-set -g userspace  
Error setting new values. Common errors:
- Do you have proper administration rights? (super-user?)
- Is the governor you requested available and modprobed?
- Trying to set an invalid policy?
- Trying to set a specific frequency, but userspace governor is not available,
   for example because of hardware which cannot be set to a specific frequency
   or because the userspace governor isn't loaded?

Any ideas?

aditsu quit because SE is EVIL
  • 395
  • @don_crissti thanks, heh, I tried echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo and got an instant kernel panic :p Then I rebooted with intel_pstate=disable and now it's using acpi-cpufreq, but I still can't set the frequency (although I'm not getting error messages anymore). Btw, why not make your comment an answer? – aditsu quit because SE is EVIL Sep 15 '14 at 05:15
  • @don_crissti I didn't know about cpupower; it has a somewhat nasty syntax, but seems to work better than cpufreq. I am able to set the frequency now :) Thanks a lot and remember to post an answer (unless you really don't want the points). – aditsu quit because SE is EVIL Sep 15 '14 at 22:46

2 Answers2

56

This is because your system is using the new driver called intel_pstate. There are only two governors available when using this driver: powersave and performance.
The userspace governor is only available with the older acpi-cpufreq driver (which will be automatically used if you disable intel_pstate at boot time; you then set the governor/frequency with cpupower):

  • disable the current driver: add intel_pstate=disable to your kernel boot line
  • boot, then load the userspace module: modprobe cpufreq_userspace
  • set the governor: cpupower frequency-set --governor userspace
  • set the frequency: cpupower --cpu all frequency-set --freq 800MHz
don_crissti
  • 82,805
1

The answer is in your question:

for core in $(seq 0 "$(($(getconf _NPROCESSORS_ONLN) - 1))"); do
echo {performance|powersave} >/sys/devices/system/cpu/cpu$core/cpufreq/scaling_governor ;
done

That and the kernel must be compiled with userspace governor enabled.

RalfFriedl
  • 8,981
Jaun Mauro Fernandez
  • 11