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Re: CPU scaling problems

On Thursday, November 15, 2012 01:34:11 PM Mark Allums wrote:
> >>>>>  Francesco wrote:
> I have installed Debian testing on a X1 Carbon, processor i5-3427U.
> My problem is the following: when the `ondemand' governor is active, the
> processor clock never scales up, it always stays at 800Mhz.  The situation
> changes when using the `conservative' or the `performance' governors.  More
> curiously, if I set `conservative'/`performance' as the governor for at
> least one core, the CPU will scale.  I am on the 3.6.6-trunk-amd64 kernel
> from experimental because the intel video driver 3.2 causes random freezes.
> To test if the scaling occurs I run `stress -c 4'.
> Things I have tried:
> * Enabling/disabling `cpufreqd', `laptop-mode', and `acpid'.  I currently
> run
>   `laptop-mode'.
> * The 3.2 kernel in testing
> * Enabling/disabling the `xfce4-power-manager', which I use to manage
>   suspends/hibernate.
> There are some kind-of relevant BIOS options and I will try with those soon
> but I doubt that's the issue.
> Does anybody have any idea on how to troubleshoot such a problem?  I
> suspect that the problem is either in the kernel or in some other software
> which is regulating the scaling.
> <<<<<
> At a guess, I would assume a configuration problem.  Or no problem.  Is
> your machine sluggish or unresponsive?  How do you know it stays at 800
> MHz? What tool do you use to monitor it?  Maybe your monitor is wrong.  I
> am not sure how to troubleshoot this, but if you don't need the governor,
> turn it off or use the 'performance' one.

In one shell, run 
  while :; do grep MHz /proc/cpuinfo; echo; sleep .25; done
and watch the clock(s); they should all be at minimum clock.

In another, run
  while :; do true; done
In the first shell, you should then see one CPU jump to full speed. <CTRL/C> 
and it should return to minimum.

If you run one for each CPU, they should all jump to full clock, the CPU temp 
should climb, and the CPU fan will speed up. Kill them all and everything 
should return to 'rest'.

For status and info, look in:
  ls /sys/devices/system/cpu/cpu*/cpufreq/

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