DELL PowerEdge + Linux で CPU 省電力

BIOS のデフォルト設定は「Active Power Controller」なので、省電力On。OS からは変更不可能。この設定を「OS Control」に変更すれば、cpufreq-set コマンドを使って、動的に CPU クロックを観測／変更できるようになる。

Linux (Ubuntu 10.04) のデフォルト戦略は ondemand。performance に変更すれば最高速。powersave に変更すれば最低速。

# sudo cpufreq-info -g
conservative ondemand userspace powersave performance
# sudo cpufreq-info -c 0 -g performance
# sudo cpufreq-info -c 1 -g powersave
# sudo cpufreq-info
cpufrequtils 006: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 2 4 6
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 10.0 us.
  hardware limits: 1.60 GHz - 2.13 GHz
  available frequency steps: 2.13 GHz, 2.00 GHz, 1.86 GHz, 1.73 GHz, 1.60 GHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 1.60 GHz and 2.13 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 1.60 GHz (asserted by call to hardware).
  cpufreq stats: 2.13 GHz:65.59%, 2.00 GHz:0.00%, 1.86 GHz:0.00%, 1.73 GHz:0.00%, 1.60 GHz:34.41% (19)
analyzing CPU 1:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 1 3 5 7
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 10.0 us.
  hardware limits: 1.60 GHz - 2.13 GHz
  available frequency steps: 2.13 GHz, 2.00 GHz, 1.86 GHz, 1.73 GHz, 1.60 GHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 1.60 GHz and 2.13 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.60 GHz (asserted by call to hardware).
  cpufreq stats: 2.13 GHz:32.69%, 2.00 GHz:0.00%, 1.86 GHz:0.00%, 1.73 GHz:0.00%, 1.60 GHz:67.31% (17)
analyzing CPU 2:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0 2 4 6
  CPUs which need to have their frequency coordinated by software: 2
  maximum transition latency: 10.0 us.
  hardware limits: 1.60 GHz - 2.13 GHz
(snip)

参考: http://www.gentoo.org/doc/ja/power-management-guide.xml, http://support.dell.com/support/edocs/systems/per610/ja/HOM/HTML/syssetup.htm kazeburo++