CPU Frequency Scaling On Linux With cpupower
CPU frequency scaling enable OS to scale the frequency of the CPU for several purpose, including power saving and for bench-marking purpose. This tutorial shows how to scale the frequency of CPU manually using cpupower .
- This is tutorial is written using Ubuntu, but also tested in Arch, should works well with other linux distro too.
- Most of the commands used below requires root permission.
Installing cpupower
Enter the command below to install the needed tools
$ sudo apt install linux-tools-common linux-tools-generic linux-tools-`uname -r` Steps before configuring the frequency
Changing your CPU driver
Run the command to attain CPU information:
$ cpupower frequency-info | grep driver It will show up something like this:
which indicates that the current driver is called intel_pstate . For more information regarding the driver, please refer to the document at kernel.org. This driver provides 2 choices of CPU governor which are performance and powersave . However, it doesn’t have the governor for us user to make customization to the frequency.
Hence, we have to replace the driver with other alternatives.
First, open the file /etc/default/grub and add the phrase intel_pstate=disable to the line GRUB_CMDLINE_LINUX_DEFAULT . After adding the phrase it should looks like
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash intel_pstate=disable" Upon the next boot, check again the driver in use. If it shows acpi-cpufreq as result then we have successfully replaced the driver. To switch it back simply remove the phrase intel_pstate=disable from the line and run update-grub again.
Changing CPU governor
$ cpupower -c 0 frequency-info The result are shown as below:
analyzing CPU 0: driver: acpi-cpufreq CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 10.0 us hardware limits: 400 MHz - 1.80 GHz available frequency steps: 1.80 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz, 900 MHz, 800 MHz, 700 MHz, 600 MHz, 500 MHz, 400 MHz available cpufreq governors: userspace performance schedutil current policy: frequency should be within 400 MHz and 1.80 GHz. The governor "userspace" may decide which speed to use within this range. current CPU frequency: Unable to call hardware current CPU frequency: 1.40 GHz (asserted by call to kernel) boost state support: Supported: yes Active: yes Within the options at available cpufreq governors , we are going to use the governor userspace which allows us to do modification. If you don’t have userspace in your list then run the command
modprobe cpufreq_userspace To choose userspace as the CPU governor and scale the frequency, run the following commands:
$ sudo cpupower frequency-set -g userspace $ sudo cpupower frequency-set -f 1400MHz The input unit for the frequency can be Hz, MHz and GHz.
Your CPU should now running at your desired speed.
$ grep MHz /proc/cpuinfo cpu MHz : 1400.082 cpu MHz : 1400.100 cpu MHz : 1400.009 cpu MHz : 1400.000 cpu MHz : 1400.026 cpu MHz : 1400.123 cpu MHz : 1400.026 cpu MHz : 1400.002