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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	se-
     lects the lowest performance values to get	the most power savings.	 Adap-
     tive 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 sys-
     tems 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 de-
		 fault 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.

BSD			       December	21, 2009			   BSD


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