Power management/Processor/ja

この記事はCPUの電源管理について説明しています. ]].

CPUの周波数スケーリング
CPU周波数スケーリングは、プロセッサの周波数を自動的に電力を節約するために、チップの発熱量を低減するために、「オンザフライ」で調整することができる技術です.

BIOS
いくつかの機能はBIOSで有効化もしくは無効化できます. 次の機能が有効化されている事を確認してください.
 * "Processor C1E support"
 * "Enhanced Speedstep (EIST)"

カーネル
次のカーネルオプションを有効化してください

プロファイルに基づいて周波数を変える役割を持つガバナーというものが必要になります.

Ticks
The processor saves the most energy when the processor stays longer in power savings mode, so reduce the amount of ticks that wakes the processor up. Details about the available tickless modes can be found in the kernel documentation.

BIOS
Some functions can be enabled or disabled in the BIOS. Check that the following are enabled:
 * "HPET"
 * "Multimedia timer"

Kernel
Activate the following kernel options:

PowerTOP
PowerTOP is a utility designed to measure, explain and minimize a computer's electrical power consumption.

When it is run, it sorts the running processes in order of how often they cause the processor to wake up. For details on installation, configuration and usage see the separate PowerTOP article.

Hprofile
It is possible to change the active CPU governor using a simple command:

Read to learn how to execute this command on startup.

Applications such as do little more than the above but with some interface on top of it. However, having to run certain commands as root depending on the system usage is not efficient for most users. It is better to automate some of the decisions of governing CPU frequency. For instance, when not wired to AC power, most users would like to have the system in a power saving mode.

This is where Hprofile comes into play. Please refer to its article for more information and configuration.

External resources

 * What exactly is a P-state? (Pt. 1) - An Intel article (kind of) explaining P-states.
 * Linux's "Ondemand" Governor Is No Longer Fit - Explains why ondemand should not be used for newer Intel core processors.