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cpuspeed - Unix, Linux Command
NAME
cpuspeed - user-space cpu frequency scaling program, v1.2.1
SYNOPSIS
cpuspeed [Options]
DESCRIPTION
cpuspeed v1.2.1
This program monitors the systems idle percentage and reduces or raises the
CPUs clock speeds and voltages accordingly to minimize power consumption
when idle and maximize performance when needed. This is the default.
The program may also optionally be configured to reduce the CPUs clock
speeds if the temperature gets too high, NOT minimize their speeds if the
computers AC adapter is disconnected or maximize their speeds when the AC
adapter is connected.
By default this program will manage every CPU found in the system.
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Options:
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-d
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Tells the process to daemonize itself (run in background).
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-i <interval>
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Sets the interval between idle percentage tests and possible speed
changes in tenths of a second (default is 20).
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-p <fast up> <threshold>
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Sets the CPU idle percentage thresholds.
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<fast up> is the idle
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percentage below which a CPU will be set to the highest possible
speed. <threshold> is the idle percentage above which a CPUs
speed will be decreased and below which a CPUs speed will be
increased (defaults are 10 and 25).
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-m <minimum speed>
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Sets the minimum speed in KHz below which a CPU will not be set.
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-M <maximum speed>
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Sets the maximum speed in KHz above which a CPU will not be set.
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-t <temp file> <maxtemp>
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Sets the ACPI temperature file and the temperature at which CPUs
will be set to minimum speed.
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-T <interval>
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Sets the interval at which the temperature will be polled in
tenths of a second (default is 10).
(Requires the -t option above.)
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-a <AC file>
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Sets the ACPI AC adapter state file and tells the program to set
the CPUs to minimum speed when the AC adapter is disconnected.
(This is the default but is changeable by the -D option below).
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-A <interval>
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Sets the interval at which the AC adapter state will be polled in
tenths of a second (default is 50).
(Requires the -a option above.)
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-C
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Run at maximum speed when AC adapter is connected.
(Requires the -a option above.)
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-D
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Do NOT force minimum speed when AC adapter is disconnected.
(Requires the -a option above.)
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-r
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Restores previous speed on program exit.
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-s <CPU>
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Manage only a single CPU.
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<CPU> specifies the number of the CPU
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to manage and is in the range 0 to (n-1) where n is the number
of CPUs in the system. Without this option the program creates
copies of itself to manage every CPU in the system.
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To have a CPU stay at the highest clock speed to maximize performance send
the process controlling that CPU the SIGUSR1 signal.
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To have a CPU stay at the lowest clock speed to maximize battery life send
the process controlling that CPU the SIGUSR2 signal.
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To resume having a CPUs clock speed dynamically scaled send the process
controlling that CPU the SIGHUP signal.
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Notes:
Many modern Linux systems support in-kernel cpu frequency scaling. The
cpuspeed daemon only works in conjunction with the userspace frequency
scaling governor. Other governors, such as ondemand and conservative,
rely on the Linux kernel to adjust cpu frequencies on the fly without the
need of any user-space assistance, such as that provided by cpuspeed.
Red Hat and Fedora distributions employ a unified configuration file
for both scenarios, as well as a cpuspeed init script that will configure
either cpuspeed or in-kernel cpu frequency scaling, as appropriate.
FILES
/etc/sysconfig/cpuspeed, configuration file
/etc/init.d/cpuspeed, initialzation script
/usr/sbin/cpuspeed, cpuspeed program
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SEE ALSO
The CPUSpeed web page:
http://carlthompson.net/Software/CPUSpeed
LICENSE
CPUSpeed is released under the GNU General Public License version 2 (or if
you wish any later version). This license allows you to use, copy,
distribute and modify the software with very few restrictions. The full
text of the license may be found here:
http://carlthompson.net/Software/CPUSpeed/License
AUTHOR(S):
Tag | Description |
CPUSpeed daemon, original init script and configuration file:
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Carl Thompson - cet [at] carlthompson.net
(copyright 2002 - 2005)
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Modernized init script, configuration file and man page:
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Dave Jones - davej [at] redhat.com
Michal Jaegermann - michal [at] harddata.com
Jarod Wilson - jwilson [at] redhat.com
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