How to use cpufrequtils - Revision history

Helge: notes update in examples section

2007-05-02T14:25:17Z

notes update in examples section

Helge: Major update with more useful information

2007-05-02T14:19:40Z

Major update with more useful information

Gvy at 07:31, 3 February 2006

2006-02-03T07:31:14Z

Gvy at 07:29, 3 February 2006

2006-02-03T07:29:47Z

Gvy: bright side

2006-02-02T18:19:25Z

bright side

84.191.139.74 at 09:19, 20 July 2005

2005-07-20T09:19:50Z

84.191.139.74 at 08:35, 20 July 2005

2005-07-20T08:35:50Z

82.67.166.141 at 11:43, 11 April 2005

2005-04-11T11:43:26Z

New page

: This package mainly has 2 programs:
/usr/bin/cpufreq-info
/usr/bin/cpufreq-set

: cpufreq-info gives general device information:
xaiki@gonzo:~$ cpufreq-info
cpufrequtils 0.2: cpufreq-info (C) Dominik Brodowski 2004
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
driver: speedstep-smi
CPUs which need to switch frequency at the same time: 0
hardware limits: 500 MHz - 700 MHz
available frequency steps: 700 MHz, 500 MHz
available cpufreq governors: userspace, performance
current policy: frequency should be within 500 MHz and 700 MHz.
The governor "userspace" may decide which speed to use
within this range.
current CPU frequency is 700 MHz.

: and cpufreq-set allows setting
... Never got it working ...

@@ Line 47: / Line 47: @@
 ===Examples===
-'''IMPORTANT NOTE!'''
+{{NOTE|Use cpufreq-info to see which frequencies and governors are available for your CPU. Examples were made on a Z60m with Intel Pentium M 2.0Ghz.}}
+{{NOTE|''sudo'' is used in these examples to grant root privileges.}}
 Activate the ''conservative'' governor to save a little extra power by letting the CPU stay longer at each frequency step before changing:

@@ Line 1: / Line 1: @@
 {{NOTE|See the [[How_to_make_use_of_Dynamic_Frequency_Scaling|Dynamic Frequency Scaling HOWTO]] on how to avoid using cpu frequency scaling daemons by using the kernel builtin ondemand governor.}}
 This package mainly has 2 programs:
 :{{path|/usr/bin/cpufreq-info}}
 :{{path|/usr/bin/cpufreq-set}}
-cpufreq-info gives general device information:
+Frequency scaling allows you to set the CPU frequency on-the-fly or specify an automatic governor. By lowering the CPU frequency when your computer is idle, you can preserve a lot of battery power and keep the system cool.
-  xaiki@gonzo:~$ cpufreq-info
-  cpufrequtils 0.2: cpufreq-info (C) Dominik Brodowski 2004
+By default most systems use the ''ondemand'' governor. For battery powered environments, the ''conservative'' and ''powersave'' governors are more favorable.
   Report errors and bugs to linux@brodo.de, please.
   analyzing CPU 0:
-    driver: speedstep-smi
+    driver: centrino
     CPUs which need to switch frequency at the same time: 0
-    hardware limits: 500 MHz - 700 MHz
+    hardware limits: 798 MHz - 2.00 GHz
-    available frequency steps: 700 MHz, 500 MHz
+    available frequency steps: 798 MHz, 1.06 GHz, 1.33 GHz, 1.60 GHz, 2.00 GHz
-    available cpufreq governors: userspace, performance
+    available cpufreq governors: userspace, ondemand, conservative, powersave, performance
-    current policy: frequency should be within 500 MHz and 700 MHz.
+    current policy: frequency should be within 798 MHz and 2.00 GHz.
-                    The governor "userspace" may decide which speed to use
+                    The governor "conservative" may decide which speed to use
                     within this range.
-    current CPU frequency is 700 MHz.
+    current CPU frequency is 798 MHz.
-and cpufreq-set allows setting
+Activate the ''conservative'' governor to save a little extra power by letting the CPU stay longer at each frequency step before changing:
-... Never got it working ...
+ user@host:~$ sudo cpufreq-set -g conservative
-I've got (ALT Linux w/2.6.14 on A30p) -- you need to get userspace governor active:
+Set the upper frequency limit to 1.6Ghz:
-# modprobe speedstep-ich cpufreq_userspace
+ user@host:~$ sudo cpufreq-set -u 1.6Ghz
-Then cpufreq-set -f 500000 (or 700000) should do the job.
+Manually set the frequency to a constant 800Mhz (userspace governor):

@@ Line 24: / Line 24: @@
 ... Never got it working ...
-I've got -- you need to get userspace governor active:
+I've got (ALT Linux w/2.6.14 on A30p) -- you need to get userspace governor active:
 # modprobe speedstep-ich cpufreq_userspace
 # echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
 Then cpufreq-set -f 500000 (or 700000) should do the job.

@@ Line 25: / Line 25: @@
 I've got -- you need to get userspace governor active:
-# modprobe cpufreq_userspace
+# modprobe speedstep-ich cpufreq_userspace
 # echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
 Then cpufreq-set -f 500000 (or 700000) should do the job.

← Older revision		Revision as of 18:19, 2 February 2006
Line 23:		Line 23:
	and cpufreq-set allows setting		and cpufreq-set allows setting
	... Never got it working ...		... Never got it working ...
		+
		+	I've got -- you need to get userspace governor active:
		+	# modprobe cpufreq_userspace
		+	# echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
		+
		+	Then cpufreq-set -f 500000 (or 700000) should do the job.