Setting of CPU Governor under Linux

This article shows how to change and read out the CPU-Governor under Linux. The CPU Governor specifies the frequency range within which a processor core may operate. If you want to have, for example, maximum performance for all CPU cores at the same time, you can achieve this via changing the CPU-Governor. Important: The changing of the CPU Scaling Governor may have a negative influence on the electricity consumption of your server, as the automatic regulation of the CPU (energy saving modes) can be completely deactivated.

Available Scaling Governor

root@pveneo:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
conservative ondemand userspace powersave performance schedutil

Active Scaling Governor

root@pveneo:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
performance

Setting of Scaling Governor

If you want to set a Scaling Governor other than the one currently active, you can do so with an echo command.

echo performance | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor 

Important: With the specification of cpu*, in the above command, the Governor is reset on all available CPU cores.

Verification of CPU frequency

With watch 'cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq', you can observe live whether the CPU frequency changes automatically after setting the Scaling Governor.

Persistent configuration

The change of the above described process is not reboot-proof. With a Cronjob, which is executed when the system starts up, however, you can have the CPU Governor reset automatically. However, a kernel parameter available since kernel 5.9 would be better: cpufreq.default_governor=<WERT>, which is set as follows:

## For legacy systems with Grub that edit Grub files
root@pveneo:~# nano /etc/default/grub

## For Systemd UEFI systems with systemd-Boot that edit cmdline 
root@pveneo:~# nano /etc/kernel/cmdline

## add Kernel parameters (example: Grub)
GRUB_CMDLINE_LINUX_DEFAULT="quiet cpufreq.default_governor=powersave"

## Grub Update
root@pveneo:~# update-grub
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-6.5.13-1-pve
Found initrd image: /boot/initrd.img-6.5.13-1-pve
Found linux image: /boot/vmlinuz-6.5.11-8-pve
Found memtest86+ 64bit EFI image: /boot/memtest86+x64.efi
Adding boot menu entry for UEFI Firmware Settings ...
done

## For systemdboot
proxmox-boot-tool refresh
update-initramfs -u

## restart server 
root@pveneo:~# reboot

## Verify if parameter is active
root@pveneo:~# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-6.5.13-1-pve root=/dev/mapper/pve-root ro quiet cpufreq.default_governor=powersave

You can also validate the function of the kernel parameter by re-reading the Scaling Governor immediately after the reboot.

root@pveneo:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
powersave

Author: Jonas Sterr Jonas Sterr has been working for Thomas-Krenn for several years. Originally employed as a trainee in technical support and then in hosting (formerly Filoo), Mr. Sterr now mainly deals with the topics of storage (SDS / Huawei / Netapp), virtualization (VMware, Proxmox, HyperV) and network (switches, firewalls) in product management at Thomas-Krenn.AG in Freyung.

Translator: Alina Ranzinger Alina has been working at Thomas-Krenn.AG since 2024. After her training as multilingual business assistant, she got her job as assistant of the Product Management and is responsible for the translation of texts and for the organisation of the department.