2f8ad6c087
cycle too much, wasting power if we trigger a jump to full speed too easily. CPU-bound tasks quickly push idle below this level.
129 lines
3.6 KiB
Groff
129 lines
3.6 KiB
Groff
.\" Copyright (c) 2005 Nate Lawson
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 26, 2005
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.Dt POWERD 8
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.Os
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.Sh NAME
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.Nm powerd
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.Nd system power control utility
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.Sh SYNOPSIS
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.Nm
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.Op Fl a mode
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.Op Fl b mode
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.Op Fl i percent
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.Op Fl n mode
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.Op Fl p ival
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.Op Fl r percent
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.Op Fl v
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.Sh DESCRIPTION
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The
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.Nm
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utility monitors the system state and sets various power control options
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accordingly.
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It offers three modes (max, min, and adaptive) that can be
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individually selected while on AC power or batteries.
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.Pp
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Maximum mode chooses the highest performance values.
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Minimum mode selects the lowest performance values to get the most power
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savings.
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Adaptive mode attempts to strike a balance by degrading performance when
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the system appears idle and increasing it when the system is busy.
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It offers a good balance between a small performance loss for greatly
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increased power savings.
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The default mode is
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adaptive.
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.Pp
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The
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.Nm
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utility recognizes the following runtime options:
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.Bl -tag -width -i_percent
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.It Fl a Ar mode
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Selects the
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.Ar mode
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to use while on AC power.
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.It Fl b Ar mode
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Selects the
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.Ar mode
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to use while on battery power.
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.It Fl i Ar percent
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Specifies the CPU idle percent level when
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adaptive
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mode should begin to degrade performance to save power.
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The default is 90% or higher.
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.It Fl n Ar mode
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Selects the
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.Ar mode
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to use normally when the AC line state is unknown.
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.It Fl p Ar ival
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Specifies a different polling interval (in milliseconds) for AC line state
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and system idle levels.
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The default is 500 ms.
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.It Fl r Ar percent
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Specifies the CPU idle percent level where
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adaptive
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mode should consider the CPU running and increase performance.
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The default is 65% or lower.
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.It Fl v
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Verbose mode.
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Messages about power changes will be printed to stdout and
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.Nm
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will operate in the foreground.
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.El
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.Sh SEE ALSO
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.Xr acpi 4 ,
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.Xr apm 4 ,
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.Xr cpufreq 4
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Fx 5.5 .
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.Sh AUTHORS
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.An Colin Percival
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first wrote
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.Pa estctrl ,
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the utility that
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.Nm
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is based on.
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.An Nate Lawson
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then updated it for
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.Xr cpufreq 4 ,
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added features, and wrote this manual page.
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.Sh BUGS
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The
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.Nm
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utility should also power down idle disks and other components besides the CPU.
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.Pp
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If
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.Nm
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is used with power_profile, they may override each other.
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.Pp
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.Nm
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should probably use the
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.Xr devctl 4
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interface instead of polling for AC line state.
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