View source for Set CPU Power Management on Linux

[[Category:General Linux]]
[[Category:Proxmox VE]]
[[Category:Guides & Tutorials]]

== Prerequisites ==

Install `cpupower` if missing:

<syntaxhighlight lang="bash">
sudo apt-get update
sudo apt-get install -y linux-cpupower
</syntaxhighlight>

Verify CPU frequency scaling support:

<syntaxhighlight lang="bash">
ls /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference
</syntaxhighlight>


== Installation ==

Create `/etc/systemd/system/cpu-thermal-control.service`:

<syntaxhighlight lang="ini">
[Unit]
Description=Apply powersave governor, balance_power EPP, and frequency limits
After=multi-user.target

[Service]
Type=oneshot
ExecStart=/bin/sh -c 'cpupower frequency-set -g powersave && echo balance_power > /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference && cpupower frequency-set -u 4GHz'
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target
</syntaxhighlight>

Enable and start the service:

<syntaxhighlight lang="bash">
sudo systemctl daemon-reload
sudo systemctl enable --now cpu-thermal-control.service
</syntaxhighlight>


== Usage & Power Save Mode ==

- The service sets CPU governor to powersave, EPP to balance_power, and caps max frequency.
- To enable more aggressive power saving, modify `ExecStart` to use:

<syntaxhighlight lang="ini">
ExecStart=/bin/sh -c 'cpupower frequency-set -g powersave && echo powersave > /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference && cpupower frequency-set -d 800MHz -u 2GHz'
</syntaxhighlight>

- Reload and restart service after changes:

<syntaxhighlight lang="bash">
sudo systemctl daemon-reload
sudo systemctl restart cpu-thermal-control.service
</syntaxhighlight>

- Check CPU frequency info:

<syntaxhighlight lang="bash">
cpupower frequency-info
</syntaxhighlight>


== For Proxmox Users ==

Proxmox defaults to performance mode causing higher CPU temps. This service:

- Switches to powersave governor,
- Applies balance_power or powersave EPP,
- Caps CPU frequency for cooler, quieter operation.

Ensure kernel supports CPU scaling and adjust frequency caps as needed for your hardware.

Start this service on Proxmox nodes to improve thermal management and power efficiency.


== Troubleshooting ==

Check service logs for errors:

<syntaxhighlight lang="bash">
journalctl -u cpu-thermal-control.service
</syntaxhighlight>

Verify permissions and CPU frequency scaling support.


== Sources ==

* [Linux cpupower Documentation](https://www.kernel.org/doc/html/latest/admin-guide/pm/cpufreq.html)
* [systemd Service Files](https://www.freedesktop.org/software/systemd/man/systemd.service.html)
* [EPP Documentation](https://www.kernel.org/doc/html/latest/admin-guide/pm/energy_perf_bias.html)