NAME¶

powerd — system power control utility

SYNOPSIS¶

powerd

[-a mode] [-b mode] [-i percent] [-m freq] [-M freq] [-n mode] [-p ival] [-P pidfile] [-r percent] [-v]

DESCRIPTION¶

The powerd utility monitors the system state and sets various power control options accordingly. It offers four modes (maximum, minimum, adaptive and hiadaptive) that can be individually selected while on AC power or batteries. The modes maximum, minimum, adaptive and hiadaptive may be abbreviated max, min, adp, hadp. Maximum mode chooses the highest performance values. Minimum mode selects the lowest performance values to get the most power savings. Adaptive mode attempts 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. Hiadaptive mode is like adaptive mode, but tuned for systems where performance and interactivity are more important than power consumption. It increases frequency faster, reduces the frequency less aggressively and will maintain full frequency for longer. The default mode is adaptive for battery power and hiadaptive for the rest. The powerd utility recognizes the following runtime options:

-a mode

Selects the mode to use while on AC power.

-b mode

Selects the mode to use while on battery power.

-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.

-m freq

Specifies the minimum frequency to throttle down to.

-M freq

Specifies the maximum frequency to throttle up to.

-n mode

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

-p ival

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

-P pidfile

Specifies an alternative file in which the process ID should be stored. The default is /var/run/powerd.pid.

-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.

-v

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

SEE ALSO¶

acpi(4), apm(4), cpufreq(4)

HISTORY¶

The powerd utility first appeared in FreeBSD 6.0.

AUTHORS¶

Colin Percival first wrote estctrl, the utility that powerd is based on. Nate Lawson then updated it for cpufreq(4), added features, and wrote this manual page.

BUGS¶

The powerd utility should also power down idle disks and other components besides the CPU. If powerd is used with power_profile, they may override each other. The powerd utility should probably use the devctl(4) interface instead of polling for AC line state.