1CPUSPEED(8)                     Program Options                    CPUSPEED(8)
2
3
4

NAME

6       cpuspeed - user-space cpu frequency scaling program, v1.5.1
7

SYNOPSIS

9       cpuspeed [Options]
10

DESCRIPTION

12       cpuspeed v1.5.1
13
14       This  program  monitors  the  system's  idle  percentage and reduces or
15       raises the CPUs' clock speeds  and  voltages  accordingly  to  minimize
16       power consumption when idle and maximize performance when needed.  This
17       is the default.
18
19       The program may also optionally be configured to reduce the CPUs' clock
20       speeds  if  the temperature gets too high, NOT minimize their speeds if
21       the computer's AC adapter is disconnected or maximize their speeds when
22       the AC adapter is connected.
23
24       By default this program will manage every CPU found in the system.
25
26              Options:
27
28       -d
29
30              Tells the process to daemonize itself (run in background).
31
32       -i <interval>
33
34              Sets  the  interval  between  idle percentage tests and possible
35              speed changes in tenths of a second (default is 20).
36
37       -p <fast up> <threshold>
38
39              Sets the CPU core idle percentage thresholds. <fast up>  is  the
40              idle  percentage below which a CPU core will be set to the high‐
41              est possible speed.  <threshold> is the  idle  percentage  above
42              which a CPU core's speed will be decreased and below which a CPU
43              core's speed will be increased (defaults are 10 and 25).
44
45       -m <minimum speed>
46
47              Sets the minimum speed in KHz below which a CPU core will not be
48              set.
49
50       -M <maximum speed>
51
52              Sets the maximum speed in KHz above which a CPU core will not be
53              set.
54
55       -n
56
57              Do not treat niced programs as idle time.
58
59       -w
60
61              Do not treat time waiting for IO as idle time.
62
63       -t <temp file> <maxtemp>
64
65              Sets the ACPI temperature file and the temperature at which CPUs
66              will be set to minimum speed.
67
68       -T <interval>
69
70              Sets  the  interval  at  which the temperature will be polled in
71              tenths of a second (default is 10).  (Requires the  '-t'  option
72              above.)
73
74       -a <AC file>
75
76              Sets the ACPI AC adapter state file and tells the program to set
77              the CPUs to minimum speed when the AC adapter  is  disconnected.
78              (This  is  the  default  but  is  changeable  by the '-D' option
79              below).
80
81       -A <interval>
82
83              Sets the interval at which the AC adapter state will  be  polled
84              in  tenths   of  a  second  (default is 50).  (Requires the '-a'
85              option above.)
86
87       -C
88
89              Run at maximum speed when AC adapter  is  connected.   (Requires
90              the '-a' option above.)
91
92       -D
93
94              Do  NOT  force  minimum  speed  when AC adapter is disconnected.
95              (Requires the '-a' option above.)
96
97       -r
98
99              Restores previous speed on program exit.
100
101       -S <CPU core 1> [[<CPU core 2>] ...]
102
103              Manage only a single group of CPU cores.  All of  the  specified
104              cores  will  controlled  as  a  single group (locked to the same
105              speed) and are in the range 0 to n-1 where 'n' is the total num‐
106              ber  of CPU cores in the system.  Note that when specifying mul‐
107              tiple cores the list must be enclosed in quotes.   Without  this
108              option the program creates copies of itself to manage every core
109              of every CPU in the system  and  automatically  determines  core
110              groups.  If  you  are  running on an old kernel and get an error
111              message about not being able to  open  an  "affected_cpus"  file
112              then  you  must  run  this  program separately for each group of
113              cores that must be controlled together (which probably means for
114              each physical CPU) and use this option.
115
116   Notes:
117       To  have a CPU core stay at the highest clock speed to maximize perfor‐
118       mance send the process controlling that CPU core the SIGUSR1 signal.
119
120       To have a CPU core stay at the lowest clock speed to  maximize  battery
121       life send the process controlling that CPU core the SIGUSR2 signal.
122
123       To  resume  having a CPU core's clock speed dynamically scaled send the
124       process controlling that CPU core the SIGHUP signal.
125
126       Many modern Linux systems support in-kernel cpu frequency scaling.  The
127       cpuspeed  daemon  only  works  in conjunction with the 'userspace' fre‐
128       quency scaling governor. Other governors, such as 'ondemand' and  'con‐
129       servative',  rely  on the Linux kernel to adjust cpu frequencies on the
130       fly without the need of any user-space assistance, such  as  that  pro‐
131       vided by cpuspeed.
132
133       Red  Hat  and  Fedora distributions employ a unified configuration file
134       for both scenarios, as well as a cpuspeed init script that will config‐
135       ure either cpuspeed or in-kernel cpu frequency scaling, as appropriate.
136

FILES

138       /etc/sysconfig/cpuspeed, configuration file
139       /etc/init.d/cpuspeed, initialzation script
140       /usr/sbin/cpuspeed, cpuspeed program
141

SEE ALSO

143       The CPUSpeed web page:
144          http://carlthompson.net/Software/CPUSpeed
145

LICENSE

147       CPUSpeed is released under the GNU General Public License version 2 (or
148       if you wish any later version). This license allows you to use, copy,
149       distribute and modify the software with very few restrictions. The full
150       text of the license may be found here:
151         http://carlthompson.net/Software/CPUSpeed/License
152

AUTHOR(S):

154       CPUSpeed daemon, original init script and configuration file:
155              Carl Thompson - cet [at] carlthompson.net
156                  (copyright 2002 - 2008)
157
158       Modernized init script, configuration file and man page:
159              Dave Jones - davej [at] redhat.com
160              Michal Jaegermann - michal [at] harddata.com
161              Jarod Wilson - jwilson [at] redhat.com
162
163
164
165cpuspeed v1.5.1                October 08, 2008                    CPUSPEED(8)