cpufrequtils がインストールされているのを確認後、
$ cpufreq-info
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
no or unknown cpufreq driver is active on this CPU
そこで、
（/etc/modules に追加しておく）
設定できる MAX_SPEED, MIN_SPEED を確認後、cpufrequtils の設定を変更。
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
1600000 1400000 1200000 1000000 800000 600000
# vi /etc/default/cpufrequtils
ENABLE="false" ……> true
GOVERNOR="ondemand" ……> conservative
MAX_SPEED=0 ……> 1600000
MIN_SPEED=0 ……> 600000
cpufrequtils を再起動後、再確認。
# /etc/init.d/cpufrequtils restart
CPUFreq Utilities: Setting conservative CPUFreq governor... CPU0 done.
$ cpufreq-info
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
driver: centrino
CPUs which need to switch frequency at the same time: 0
hardware limits: 600 MHz - 1.60 GHz
available frequency steps: 1.60 GHz, 1.40 GHz, 1.20 GHz, 1000 MHz, 800 MHz, 600 MHz
available cpufreq governors: conservative, performance
current policy: frequency should be within 600 MHz and 1.60 GHz.
The governor "conservative" may decide which speed to use
within this range.
current CPU frequency is 600 MHz.
これで、負荷に応じて CPU の速度が 600MHz〜1.6GHz で変化するようになった。
なお、governor には以下のものがある。
・ondemand：Dynamic cpufreq policy governor, changes frequency based on the processor load.
・conservative：Similar to ondemand, but increases frequency step by step if you need more power.
・powersave：Sets to the lowest frequency.
userspace：Allows you to set the frequency manually by editing /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed.
・performance：Sets to the highest frequency.
