Arch Linux

JohnnySSH

Member

Registered: 2013-05-04

Posts: 82

CPU Freq Scaling not working - stuck at max on Lenovo X220?

Hi,

not sure if anyone has had this issue before but it seems to be an intermittent thing with updates.

Having gone through:

https://wiki.archlinux.org/index.php/CP … cy_scaling

and a bit of Oogling led me to:

https://bbs.archlinux.org/viewtopic.php?id=95770

- exactly the opposite of what I'm experiencing.

For what ever reason my cpu is stuck at Max frequency rather then dynamically allocating or lowest.

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 - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 2.80 GHz (asserted by call to hardware).
  boost state support:
    Supported: no
    Active: no
    3300 MHz max turbo 4 active cores
    3300 MHz max turbo 3 active cores
    3300 MHz max turbo 2 active cores
    3500 MHz max turbo 1 active cores

The machine is a Lenovo X220 with i7 cpu.....

Trying to set the frequency by hand just gives an error?

cpupower frequency-set -f 800
Setting cpu: 0
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?

Either I'm missing something or there's something more to things......

- doing above commands from 'su' as root!!

This is a bit of an issue as the system doesn't take long to overheat in this instance at all.

Watching cpu speed using - watch grep \"cpu MHz\" /proc/cpuinfo - gives:

Every 2.0s: grep "cpu MHz" /proc/cpuinfo                                                                                                        Wed Aug 13 15:08:41 2014

cpu MHz         : 2797.593
cpu MHz         : 2800.000

Can anyone suggest something I can try?

I have already tried unplugging the PSU, and rebooting but same thing again?

Thanks.

[EDIT]
Speedstep and kernel Turbo mode are both set to off as they seem to make things worse.

Last edited by JohnnySSH (2014-08-13 14:11:06)

JohnnySSH

Member

Registered: 2013-05-04

Posts: 82

Re: CPU Freq Scaling not working - stuck at max on Lenovo X220?

Just wanted to quickly mention that updating the kernel to 3.16.1-1 seems to have fixed the issue for now? Perhaps it was simply a kernel patch that wasn't applied at compile time????

Pse

Member

Registered: 2008-03-15

Posts: 413

Re: CPU Freq Scaling not working - stuck at max on Lenovo X220?

The Intel P-State driver (which you are using) saves power regardless of the current CPU frequency (that is, you can't tell whether power saving is working by looking at the current frequency of your CPU). To see whether power saving is working, you need either powertop or i7z. You can check the amount of time each core spends in each power setting (C7 being the lowest, IIRC) with those tools.

Last edited by Pse (2014-08-17 02:23:41)

JohnnySSH

Member

Registered: 2013-05-04

Posts: 82

Re: CPU Freq Scaling not working - stuck at max on Lenovo X220?

Thanks for response. However:

Watching cpu speed using - watch grep \"cpu MHz\" /proc/cpuinfo - gives:

This is exactly what the Wiki suggested and via the above the frequency was maxed out.

If I view it now it shows 8xx MHz, which is also what i7z is showing too....