powerd man page on FreeBSD

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POWERD(8)		  BSD System Manager's Manual		     POWERD(8)

     powerd — system power control utility

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

     The powerd utility monitors the system state and sets various power con‐
     trol options accordingly.	It offers four modes (maximum, minimum, adap‐
     tive 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 fre‐
     quency less aggressively and will maintain full frequency for longer.
     The default mode is adaptive for battery power and hiadaptive for the

     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

     -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.

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

     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.

BSD			       December 21, 2009			   BSD

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