powerd8

Usage

Overview

The powerd utility monitors the system state and sets various power control options accordingly. It offers power-saving modes that can be individually selected for operation on AC power or batteries.

maximum

Choose the highest performance values. May be abbreviated as max.

minimum

Choose the lowest performance values to get the most power savings. May be abbreviated as min.

adaptive

Attempt to strike a balance by degrading performance when the system appears idle and increasing it when the system is busy. It offers a good balance between a small performance loss for greatly increased power savings. May be abbreviated as adp.

hiadaptive

Like adaptive mode, but tuned for systems where performance and interactivity are more important than power consumption. It increases frequency faster, reduces frequency less aggressively, and will maintain full frequency for longer. May be abbreviated as hadp.

The default mode is adaptive for battery power and hiadaptive for the rest.

powerd recognizes these runtime options:

-a mode

Selects the mode to use while on AC power.

Not on Linux.

-b mode

Selects the mode to use while on battery power.

Not on Linux.

-i percent

Specifies the CPU load percent level when adaptive mode should begin to degrade performance to save power. The default is 50% or lower.

Not on Linux.

-M freq

Specifies the maximum frequency to throttle up to.

Not on Linux.

-m freq

Specifies the minimum frequency to throttle down to.

Not on Linux.

-N

Treat "nice" time as idle for the purpose of load calculation; i.e., do not increase the CPU frequency if the CPU is only busy with "nice" processes.

Not on Linux.

-n mode

Selects the mode to use normally when the AC line state is unknown.

Not on Linux.

-P pidfile

Specifies an alternative file in which the process ID should be stored.

Not on Linux.

-p ival

Specifies a different polling interval (in milliseconds) for AC line state and system idle levels. The default is 250 ms.

Not on Linux.

-r percent

Specifies the CPU load percent level where adaptive mode should consider the CPU running and increase performance. The default is 75% or higher.

Not on Linux.

-s source

Enforces method for AC line state refresh; by default, it is chosen automatically. The set of valid methods is sysctl, devd and apm (i386 only).

Not on Linux.

-v

Verbose mode. Messages about power changes will be printed to stdout and powerd will operate in the foreground.

Not on Linux.

Files

/var/run/powerd.pid

The default PID file.