[Grml] Re: Controlling CPU Frequency

- Tong - mlist4suntong at yahoo.com
Sat Aug 4 00:48:32 CEST 2007

Thanks for the answer. Here are the updates:

% modprobe thermal && echo OK

% cpufreq-info
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux at brodo.de, please.
analyzing CPU 0:
  no or unknown cpufreq driver is active on this CPU

% source /usr/bin/cpufreq-detect.sh

% echo $MODULE

% modprobe $MODULE
FATAL: Error inserting powernow_k8 (/lib/modules/2.6.20-grml/kernel/arch/i386/kernel/cpu/cpufreq/powernow-k8.ko): No such device

% dir /lib/modules/2.6.20-grml/kernel/arch/i386/kernel/cpu/cpufreq/powernow-k8.ko
-rw-r--r-- 1 root root 15387 05-03 15:10 /lib/modules/2.6.20-grml/kernel/arch/i386/kernel/cpu/cpufreq/powernow-k8.ko

% cat  /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor: No such file or directory

% ls /sys/devices/system/cpu/cpu0/cpufreq
No such file or directory

To recap, the problems I see are:

- The thermal kernel loaded ok, but cpufreq-info still says no driver is active

- cpufreq-detect.sh successfully detected my CPU module, 
  but modprobe return weird error "No such device". 

Here are more testing/info:

% mkdir /sys/devices/system/cpu/cpu0/cpufreq
mkdir: cannot create directory `/sys/devices/system/cpu/cpu0/cpufreq': Operation not permitted

% /etc/init.d/powernowd start
Starting powernowd: required sysfs objects not found!

$ grep sysfs /etc/fstab
sysfs /sys sysfs defaults 0 0

# just shooting into the dark
% modprobe cpufreq_userspace && echo OK
# afterward, cpufreq-info returns the same

% cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
# This file should contain the names of kernel modules that are
# to be loaded at boot time, one per line.  Comments begin with
# a `#', and everything on the line after them are ignored.


# Generated by sensors-detect on Wed Aug  1 18:23:39 2007
# I2C adapter drivers
# Chip drivers

On Thu, 02 Aug 2007 09:58:25 +0200, Michael Prokop wrote:

>> BTW, anybody know the 'conservative' governor?
> Yes. ;) But I usually prefer the ondemand governor.

Just FYI, seems that conservative is newer than ondemand:

http://www.linuxfromscratch.org/hints/downloads/files/cpufreq.txt :
As of 2.6.9, an 'ondemand' driver was made available.  Other demand-based
governors, such as 'conservative', have been introduced in later kernels.

http://ftp.kernel.org/pub/linux/kernel/people/lenb/acpi/doc/OLS2006-ondemand-paper.pdf :
conservative governor is a fork of the ondemand governor with a slightly
different algorithm to decide on the target frequency. Most of the
configuration details of ondemand in this paper also holds true for the
conservative governor.

Of course, newer might not grantee better. :-)

Tong (remove underscore(s) to reply)

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