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POWERD(8)		FreeBSD	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/

     -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.

FreeBSD	8.2		       December	21, 2009		   FreeBSD 8.2


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