powerd — system
power control utility
powerd |
[-a mode]
[-b mode]
[-i percent]
[-m freq]
[-M freq]
[-N] [-n
mode] [-p
ival] [-P
pidfile] [-r
percent] [-s
source] [-v] |
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.
-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- 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.
-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.
-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).
-v- Verbose mode. Messages about power changes will be printed to stdout and
powerd will operate in the foreground.
The powerd utility first appeared in
FreeBSD 6.0.
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.
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.