freebsd-src/usr.sbin/powerd/powerd.8

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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
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\"
.Dd February 25, 2023
.Dt POWERD 8
.Os
.Sh NAME
.Nm powerd
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.Nd "system power control utility"
.Sh SYNOPSIS
.Nm
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.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
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.Op Fl n Ar mode
.Op Fl P Ar pidfile
.Op Fl p Ar ival
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.Op Fl r Ar percent
.Op Fl s Ar source
.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 "hiadaptive"
.It Cm maximum
Choose the highest performance values.
May be abbreviated as
.Cm max .
.It Cm minimum
Choose the lowest performance values to get the most power savings.
May be abbreviated as
.Cm min .
.It Cm 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
.Cm adp .
.It Cm hiadaptive
Like
.Cm 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
.Cm hadp .
.El
.Pp
The default mode is
.Cm adaptive
for battery power and
.Cm hiadaptive
for the rest.
.Pp
.Nm
recognizes these runtime options:
.Bl -tag -width "-r 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
Set of powerd enchancements: 1. Make it more SMP polite. Previous version uses average CPU load that often leads to load underestimation. It make powerd with default configuration unusable on systems with more then 2 CPUs. I propose to use summary load instead of average one. IMO this is the best we can do without specially tuned scheduler. Also as soon as measuring total load on SMP systems is more useful then total idle, I have switched to it. 2. Make powerd's operation independent from number and size of frequency levels. I have added internal frequency counter which translated into real frequencies only on a last stage and only as good as gone. Some systems may have only several power levels, while others - many of them, so adaptation time with previous approach was completely different. 3. As part of previous I have changed adaptive mode to rise frequency on demand up to 2 times and fall on 1/8 per time internal. 4. For desktop (AC-powered) systems I have added one more mode - "hiadaptive". It rises frequency twice faster, drops it 4 times slower, prefers twice lower CPU load and has additional delay before leaving the highest frequency after the period of maximum load. This mode was specially made to improve interactivity of the systems where operation capabilities are more significant then power consumption, but keeping maximum frequency all the time is not needed. 5. I have reduced default polling interval from 1/2 to 1/4 of second. It is not so important for algorithm math now, but gives better system interactivity. Discussed on: mobile@
2008-11-18 13:24:38 +00:00
Specifies the CPU load percent level when adaptive
mode should begin to degrade performance to save power.
Set of powerd enchancements: 1. Make it more SMP polite. Previous version uses average CPU load that often leads to load underestimation. It make powerd with default configuration unusable on systems with more then 2 CPUs. I propose to use summary load instead of average one. IMO this is the best we can do without specially tuned scheduler. Also as soon as measuring total load on SMP systems is more useful then total idle, I have switched to it. 2. Make powerd's operation independent from number and size of frequency levels. I have added internal frequency counter which translated into real frequencies only on a last stage and only as good as gone. Some systems may have only several power levels, while others - many of them, so adaptation time with previous approach was completely different. 3. As part of previous I have changed adaptive mode to rise frequency on demand up to 2 times and fall on 1/8 per time internal. 4. For desktop (AC-powered) systems I have added one more mode - "hiadaptive". It rises frequency twice faster, drops it 4 times slower, prefers twice lower CPU load and has additional delay before leaving the highest frequency after the period of maximum load. This mode was specially made to improve interactivity of the systems where operation capabilities are more significant then power consumption, but keeping maximum frequency all the time is not needed. 5. I have reduced default polling interval from 1/2 to 1/4 of second. It is not so important for algorithm math now, but gives better system interactivity. Discussed on: mobile@
2008-11-18 13:24:38 +00:00
The default is 50% or lower.
.It Fl M Ar freq
Specifies the maximum frequency to throttle up to.
.It Fl m Ar freq
Specifies the minimum frequency to throttle down to.
.It Fl N
Treat "nice" time as idle for the purpose of load calculation;
i.e., do not increase the CPU frequency if the CPU is only busy
with "nice" processes.
.It Fl n Ar mode
Selects the
.Ar mode
to use normally when the AC line state is unknown.
.It Fl P Ar pidfile
Specifies an alternative file in which the process ID should be stored.
.It Fl p Ar ival
Specifies a different polling interval (in milliseconds) for AC line state
and system idle levels.
Set of powerd enchancements: 1. Make it more SMP polite. Previous version uses average CPU load that often leads to load underestimation. It make powerd with default configuration unusable on systems with more then 2 CPUs. I propose to use summary load instead of average one. IMO this is the best we can do without specially tuned scheduler. Also as soon as measuring total load on SMP systems is more useful then total idle, I have switched to it. 2. Make powerd's operation independent from number and size of frequency levels. I have added internal frequency counter which translated into real frequencies only on a last stage and only as good as gone. Some systems may have only several power levels, while others - many of them, so adaptation time with previous approach was completely different. 3. As part of previous I have changed adaptive mode to rise frequency on demand up to 2 times and fall on 1/8 per time internal. 4. For desktop (AC-powered) systems I have added one more mode - "hiadaptive". It rises frequency twice faster, drops it 4 times slower, prefers twice lower CPU load and has additional delay before leaving the highest frequency after the period of maximum load. This mode was specially made to improve interactivity of the systems where operation capabilities are more significant then power consumption, but keeping maximum frequency all the time is not needed. 5. I have reduced default polling interval from 1/2 to 1/4 of second. It is not so important for algorithm math now, but gives better system interactivity. Discussed on: mobile@
2008-11-18 13:24:38 +00:00
The default is 250 ms.
.It Fl r Ar percent
Set of powerd enchancements: 1. Make it more SMP polite. Previous version uses average CPU load that often leads to load underestimation. It make powerd with default configuration unusable on systems with more then 2 CPUs. I propose to use summary load instead of average one. IMO this is the best we can do without specially tuned scheduler. Also as soon as measuring total load on SMP systems is more useful then total idle, I have switched to it. 2. Make powerd's operation independent from number and size of frequency levels. I have added internal frequency counter which translated into real frequencies only on a last stage and only as good as gone. Some systems may have only several power levels, while others - many of them, so adaptation time with previous approach was completely different. 3. As part of previous I have changed adaptive mode to rise frequency on demand up to 2 times and fall on 1/8 per time internal. 4. For desktop (AC-powered) systems I have added one more mode - "hiadaptive". It rises frequency twice faster, drops it 4 times slower, prefers twice lower CPU load and has additional delay before leaving the highest frequency after the period of maximum load. This mode was specially made to improve interactivity of the systems where operation capabilities are more significant then power consumption, but keeping maximum frequency all the time is not needed. 5. I have reduced default polling interval from 1/2 to 1/4 of second. It is not so important for algorithm math now, but gives better system interactivity. Discussed on: mobile@
2008-11-18 13:24:38 +00:00
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 s Ar source
Enforces method for AC line state refresh; by default, it is chosen
automatically.
The set of valid methods is
.Cm sysctl , devd
and
.Cm apm
(i386 only).
.It Fl v
Verbose mode.
Messages about power changes will be printed to stdout and
.Nm
will operate in the foreground.
.El
.Sh FILES
.Bl -tag -width "/var/run/powerd.pid"
.It Pa /var/run/powerd.pid
The default PID file.
.El
.Sh SEE ALSO
.Xr acpi 4 ,
.Xr apm 4 ,
.Xr cpufreq 4 ,
.Xr rc.conf 5
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 6.0 .
.Sh AUTHORS
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.An -nosplit
.An Colin Percival
first wrote
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.Nm estctrl ,
the utility that
.Nm
is based on.
.An Nate Lawson
then updated it for
.Xr cpufreq 4 ,
2005-02-27 15:49:07 +00:00
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
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is used with
.Pa /etc/rc.d/power_profile ,
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they may override each other.
.Pp
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The
.Nm
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utility
should probably use the
.Xr devctl 4
interface instead of polling for AC line state.