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.\" Copyright (c) 2005 Nate Lawson
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd November 6, 2005
.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 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 three modes (maximum, minimum, and adaptive) that can be
individually selected while on AC power or batteries.
.Pp
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.
The default mode is
adaptive.
.Pp
The
.Nm
utility recognizes the following 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 idle percent level when
adaptive
mode should begin to degrade performance to save power.
The default is 90% or higher.
.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 500 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 idle percent level where
adaptive
mode should consider the CPU running and increase performance.
The default is 65% or lower.
.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.
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