[solved] cpupower unable to set ondemand governor

tririver · 2013-11-27 15:15:10

Hi, all,

On my newly installed box, I found that after installing cpupower, I cannot set the ondemand governor. The system stays at highest frequency. (I could use powersave, which works, but not as useful as ondemand). The cpu is intel 4800mq.

~$ cpupower frequency-info
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 - 3.70 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 3.70 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  boost state support:
    Supported: yes
    Active: yes

I have installed related packages such as laptop-mode-tools and acpid. As I checked from arch wiki, one may need to load kernel module cpufreq_governor. However, I don't have this module on system

~$ sudo modprobe cpufreq_governor
modprobe: FATAL: Module cpufreq_governor not found.

Any suggestions? Thanks!

Last edited by tririver (2013-11-27 17:09:16)

pks · 2013-11-27 15:16:45

The intel_pstate cpufreq driver has its own governor, so you cannot use any of the usually available governors with it.

Edit: you can control the intel_pstate through the files max_perf_pct, min_perf_pct and no_turbo in /sys/devices/system/cpu/intel_pstate. See [1] for more info.

[1] http://www.reddit.com/r/linux/comments/ … l_pstates/

Last edited by pks (2013-11-27 15:21:28)

WonderWoofy · 2013-11-27 15:29:41

It is highly recommended that if your processor is compatible, you should use the intel_pstate driver. But there are some folks out there who experience bugs with it and their processor's power saving goes awry (for most it works amazingly, but it is new software after all). So if you fall into this category, which doesn't appear to be the case, you can disable it from the kernel command line.

tririver · 2013-11-27 17:08:53

Thanks a lot @pks and @WonderWoofy!

My case is very simple. I don't need to do anything other than use the p_state driver.

The "highest frequency" issue I mentioned is a combination of two effects: (1) /proc/cpuinfo reports a high frequency, but it doesn't matter. (2) KDE desktop search is running in the background, which makes the laptop hotter than I expected. I disabled the KDE desktop search and disregarded the cpuinfo report. Now the laptop is quiet, cool and consumes ~15W, and I am satisfied with this result.

WonderWoofy · 2013-11-27 18:03:47

It is not about the frequency being reported at any given moment. Processors can change frequency in microseconds, which no tool can properly poll. What matters is the processor's ability to reach the c-states. These are the sleep states of the given processor. Powertop, i7z, and turbostat can give you this info. But since you have a Haswell, which supports even deeper sleep states than Ivy Bridge and Sandy Bridge, you may need to use the git version of some of those.

(turbostat is provided by the kernel source, though there is in AUR package that builds it as a separate installed binary)

Arch Linux

#1 2013-11-27 15:15:10

[solved] cpupower unable to set ondemand governor

#2 2013-11-27 15:16:45

Re: [solved] cpupower unable to set ondemand governor

#3 2013-11-27 15:29:41

Re: [solved] cpupower unable to set ondemand governor

#4 2013-11-27 17:08:53

Re: [solved] cpupower unable to set ondemand governor

#5 2013-11-27 18:03:47

Re: [solved] cpupower unable to set ondemand governor

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