For 3.x kernels
The interface to CPUFreq has changed in the newer kernels. This would include CentOS 6. You can read about the entire interface here in the Red Hat Enterprise Linux (RHEL) documentation titled: Chapter 3. Core Infrastructure and Mechanics.
Specifically the section on CPUFreq Setup. Here are the steps required to set it up.
CPUFreq drivers
$ ls -1 /lib/modules/`uname -r`/kernel/arch/x86/kernel/cpu/cpufreq/
acpi-cpufreq.ko
mperf.ko
p4-clockmod.ko
pcc-cpufreq.ko
powernow-k8.ko
speedstep-lib.ko
load appropriate driver
$ modprobe acpi-cpufreq
install cpupower tool
$ yum install cpupowerutils
view governors
$ cpupower frequency-info --governors
analyzing CPU 0:
ondemand userspace performance
So we currently only have these 3 governors loaded: ondemand, userspace, and performance.
loading governors that are missing
You can get a list of all governors that are available like so.
$ ls -1 /lib/modules/`uname -r`/kernel/drivers/cpufreq/
cpufreq_conservative.ko
cpufreq_ondemand.ko
cpufreq_powersave.ko
cpufreq_stats.ko
freq_table.ko
$ modprobe cpufreq_powersave
confirm modules thus far:
$ lsmod |grep cpuf
cpufreq_powersave 1196 0
cpufreq_ondemand 10544 8
acpi_cpufreq 7763 0
freq_table 4936 2 cpufreq_ondemand,acpi_cpufreq
mperf 1557 1 acpi_cpufreq
confirm which governors are loaded
$ cpupower frequency-info --governors
analyzing CPU 0:
powersave ondemand userspace performance
viewing current policy
$ cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1 2 3 4 5 6 7
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 1.60 GHz - 3.20 GHz
available frequency steps: 3.20 GHz, 3.20 GHz, 3.07 GHz, 2.93 GHz, 2.80 GHz, 2.67 GHz, 2.53 GHz, 2.40 GHz, 2.27 GHz, 2.13 GHz, 2.00 GHz, 1.87 GHz, 1.73 GHz, 1.60 GHz
available cpufreq governors: powersave, ondemand, userspace, performance
current policy: frequency should be within 1.60 GHz and 3.20 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.60 GHz (asserted by call to hardware).
boost state support:
Supported: yes
Active: yes
2500 MHz max turbo 4 active cores
2500 MHz max turbo 3 active cores
2500 MHz max turbo 2 active cores
2600 MHz max turbo 1 active cores
In the above output you can see my current policy is ondemand. To tune the policy and speed you use this command to do so:
$ cpupower frequency-set --governor performance
Setting cpu: 0
Setting cpu: 1
Setting cpu: 2
Setting cpu: 3
Setting cpu: 4
Setting cpu: 5
Setting cpu: 6
Setting cpu: 7
confirm new governor
$ cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1 2 3 4 5 6 7
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 1.60 GHz - 3.20 GHz
available frequency steps: 3.20 GHz, 3.20 GHz, 3.07 GHz, 2.93 GHz, 2.80 GHz, 2.67 GHz, 2.53 GHz, 2.40 GHz, 2.27 GHz, 2.13 GHz, 2.00 GHz, 1.87 GHz, 1.73 GHz, 1.60 GHz
available cpufreq governors: powersave, ondemand, userspace, performance
current policy: frequency should be within 1.60 GHz and 3.20 GHz.
The governor "performance" may decide which speed to use
within this range.
current CPU frequency is 3.20 GHz (asserted by call to hardware).
boost state support:
Supported: yes
Active: yes
2500 MHz max turbo 4 active cores
2500 MHz max turbo 3 active cores
2500 MHz max turbo 2 active cores
2600 MHz max turbo 1 active cores
You can also tune the min/max CPU frequencies within a policy using the cpupower frequency-set --min <freq> --max <freq>. See this page for more details on what you can do with cpupower frequency-set.
doing the above without cpupowerutils
So finally, if you don't have the cpupowerutils package installed, you can interact with it similar to how you did in the previous 2.6 kernels. Mainly you echo values into the sysfs filesystem.
for example
$ echo 360000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
For 2.6 kernels
You can read about the various cpufreq features over on this site.
ignore_nice_load - This parameter takes a value of '0' or '1'. When
set to '0' (its default), all processes are counted towards the 'cpu
utilization' value. When set to '1', the processes that are run with a
'nice' value will not count (and thus be ignored) in the overall usage
calculation. This is useful if you are running a CPU intensive
calculation on your laptop that you do not care how long it takes to
complete as you can 'nice' it and prevent it from taking part in the
deciding process of whether to increase your CPU frequency. To turn
this on do the following.
sudo sh -c "echo 1 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice_load"
I'd put a 0 in this file since this should be the default. If you have any long running niced process, which I highly doubt, you can set it to 1.
Assuming your governor is the intel_pstate (default for Intel Sandy Bridge and Ivy Bridge CPUs as of kernel 3.9). This issue is not specific to Arch, but all distros using the new Intel pstate driver for managing CPU frequency/power management. Arch linux CPU frequency scaling.
Theodore Ts'o wrote his explanation on Google+:
- intel_pstate can be disabled at boot-time with kernel arg
intel_pstate=disable
- The problem with the ondemand governor is that it doesn't know the specific capabilities of the CPU
- Executing some tasks with higher frequency will consume less power than would a lower frequency taking more time e.g. arithmetic stuff, but not true for all tasks e.g. loading something from memory
- The intel_pstate driver knows the details of the how the CPU works and it does a better job than the generic ACPI solution
- intel_pstate offers only two governors,
powersave and performance. Intel claims that the intel_pstate "powersave" is faster than the generic acpi governor with "performance"
To change back to the ACPI driver, reboot and set the kernel arg intel_pstate=disable
Then execute modprobe acpi-cpufreq and you should have the ondemand governor available.
You can make the changes permanent by editing /etc/default/grub and adding
GRUB_CMDLINE_LINUX_DEFAULT="intel_pstate=disable"
And then updating grub.cfg ala grub-mkconfig -o /boot/grub/grub.cfg
Follow the instructions for Arch kernel module loading
and add the acpi-cpufreq module.
Best Answer
This is related to a new driver introduced in Fedora 20 that does not need more than those two governors. See this thread CPU Governors - where is ONDEMAND? for details.
To have the missing governors, you should boot with the kernel parameter
intel_pstate=disable.To do so, in the GRUB boot screen, choose "edit boot commandline" and add this to the line which starts with
kernel. You can also add it permanently to the grub config file.Note that normally you should not need others governors than those proposed by the new driver which does its job perfectly.