.\" Copyright (c) 2005 Nate Lawson
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.\" $FreeBSD$
.\"
.Dd July 4, 2013
.Dt POWERD 8
.Os
.Sh NAME
.Nm powerd
.Nd "system power control utility"
.Sh SYNOPSIS
.Nm
.Op Fl a Ar mode
.Op Fl b Ar mode
.Op Fl i Ar percent
.Op Fl m Ar freq
.Op Fl M Ar freq
.Op Fl n Ar mode
.Op Fl p Ar ival
.Op Fl P Ar pidfile
.Op Fl r Ar percent
.Op Fl v
.Sh DESCRIPTION
The
.Nm
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.
.Bl -tag -width ".Ar hiadaptive"
.It Ar maximum
Choose the highest performance values.
May be abbreviated as
.Ar max .
.It Ar minimum
Choose the lowest performance values to get the most power savings.
May be abbreviated as
.Ar min .
.It Ar 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
.Ar adp .
.It Ar hiadaptive
Like
.Ar 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
.Ar hadp .
.El
.Pp
The default mode is
.Ar adaptive
for battery power and
.Ar hiadaptive
for the rest.
.Pp
.Nm
recognizes these runtime options:
.Bl -tag -width ".Fl r Ar percent"
.It Fl a Ar mode
Selects the
.Ar mode
to use while on AC power.
.It Fl b Ar mode
Selects the
.Ar mode
to use while on battery power.
.It Fl i Ar percent
Specifies the CPU load percent level when adaptive
mode should begin to degrade performance to save power.
The default is 50% or lower.
.It Fl m Ar freq
Specifies the minimum frequency to throttle down to.
.It Fl M Ar freq
Specifies the maximum frequency to throttle up to.
.It Fl n Ar mode
Selects the
.Ar mode
to use normally when the AC line state is unknown.
.It Fl p Ar ival
Specifies a different polling interval (in milliseconds) for AC line state
and system idle levels.
The default is 250 ms.
.It Fl P Ar pidfile
Specifies an alternative file in which the process ID should be stored.
The default is
.Pa /var/run/powerd.pid .
.It Fl r Ar percent
Specifies the CPU load percent level where adaptive
mode should consider the CPU running and increase performance.
The default is 75% or higher.
.It Fl v
Verbose mode.
Messages about power changes will be printed to stdout and
.Nm
will operate in the foreground.
.El
.Sh SEE ALSO
.Xr acpi 4 ,
.Xr apm 4 ,
.Xr cpufreq 4
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 6.0 .
.Sh AUTHORS
.An -nosplit
.An Colin Percival
first wrote
.Nm estctrl ,
the utility that
.Nm
is based on.
.An Nate Lawson
then updated it for
.Xr cpufreq 4 ,
added features, and wrote this manual page.
.Sh BUGS
The
.Nm
utility should also power down idle disks and other components besides the CPU.
.Pp
If
.Nm
is used with
.Pa power_profile ,
they may override each other.
.Pp
The
.Nm
utility
should probably use the
.Xr devctl 4
interface instead of polling for AC line state.