# p4-clockmod: problem with scaling_min_freq [solved]

## tuxian

Hi,

since Upgrade from linux-2.6.15-gentoo-r1 to linux-2.6.16-gentoo-r7 I have the Problem that

/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq contains 2250000, so my min. freq is 2,25GHz,

with linux-2.6.15-gentoo-r1 scaling_min_freq had reported 375000 (375MHz).

I didn't changed the kernel-config.

It is also not possible to change scaling_min_freq to 375000.

I use SMP but also I can't image that this settting is responsible for my problem because it worked fine with linux-2.6.15-gentoo-r1.

```
root@nemesis: pts/1: 29 files 20Mb -> LC_ALL="en" cpufreq-info

cpufrequtils 001: cpufreq-info (C) Dominik Brodowski 2004-2006

Report errors and bugs to linux@brodo.de, please.

analyzing CPU 0:

  driver: p4-clockmod

  CPUs which need to switch frequency at the same time: 0 1

  hardware limits: 2.25 GHz - 3.00 GHz

  available frequency steps: 2.25 GHz, 2.63 GHz, 3.00 GHz

  available cpufreq governors: ondemand, powersave, userspace, performance

  current policy: frequency should be within 2.25 GHz and 3.00 GHz.

                  The governor "ondemand" may decide which speed to use

                  within this range.

  current CPU frequency is 2.25 GHz (asserted by call to hardware).

analyzing CPU 1:

  driver: p4-clockmod

  CPUs which need to switch frequency at the same time: 0 1

  hardware limits: 2.25 GHz - 3.00 GHz

  available frequency steps: 2.25 GHz, 2.63 GHz, 3.00 GHz

  available cpufreq governors: ondemand, powersave, userspace, performance

  current policy: frequency should be within 2.25 GHz and 3.00 GHz.

                  The governor "ondemand" may decide which speed to use

                  within this range.

  current CPU frequency is 2.25 GHz (asserted by call to hardware).
```

Last edited by tuxian on Tue Jun 20, 2006 6:09 pm; edited 1 time in total

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## tuxian

*BUMP*

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## gami

There seem to have been changes to the P4 clockmod code that disable frequencies less than 2GHz on certain CPUs. See e.g. http://lkml.org/lkml/2006/3/21/399, http://lkml.org/lkml/2006/1/4/328

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## tuxian

Which sense makes that?

It think the power consumption is higher wenn running with 2,25Ghz instead of 375MHz.

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## gami

Power consumption vs system stability?

Seems to have been an attempt to fix systems with a "N60 errata". Search for "p4-clockmod site:lklm.org" on google for quite a few discussions around this.

Tim Phipps posted a patch for inclusion in 2.6.17 to fix this (http://lkml.org/lkml/2006/4/13/104). Haven't tested it yet.

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## tuxian

My system was very stable with the previous kernel version with allowed a minimum frequency of 375MHz (uptime more than 100 days).

Thank you for the information, I mark this thread as solved.

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