throttled

throttled is a Linux daemon that prevents unwanted CPU throttling on some Intel-based systems. It periodically restores package power limits (PL1/PL2) and the temperature target in MSR and MCHBAR registers when firmware or the embedded controller resets them.

It also supports separate AC and battery profiles, undervolting, IccMax, cTDP, HWP hints, and live throttling diagnostics.

Caution

throttled runs as root and writes directly to CPU and chipset registers. Incorrect power, temperature, voltage, or current values can make a system unstable or damage hardware. Review the configuration for your CPU and cooling system before enabling the service.

When to use it

Use throttled when an Intel laptop or small-form-factor system runs below its expected frequency because firmware repeatedly applies overly conservative power or temperature limits. Confirm the problem first with s-tui, turbostat, or:

sudo throttled --monitor

The project started as a workaround for the Lenovo T480, T480s, and X1 Carbon Gen 6, but users have reported success on many Lenovo, Dell, HP, Microsoft, and ASUS systems. Support depends on the CPU, firmware, and kernel rather than the laptop brand. See the community-reported hardware list.

Features

• Restores configurable PL1, PL2, time-window, and temperature limits.
• Uses independent AC and battery profiles and reacts to power-source changes.
• Re-applies settings after suspend and hibernation through system D-Bus.
• Supports configurable CPU, cache, GPU, System Agent, and Analog I/O undervolting where firmware permits it.
• Supports IccMax overrides and experimental cTDP, HWP, and BD PROCHOT controls.
• Reloads /etc/throttled.conf automatically when the file changes.
• Reports thermal, power, current, and cross-domain throttling causes in real time.
• Runs with systemd, OpenRC, or runit.

Installation

Release packages

The latest release provides native packages and Python distributions. Native packages include the daemon, default configuration, and service definition.

System	Package
Debian-family system with python3-dbus-fast	DEB
Fedora-family system	RPM
Alpine edge/testing	APK
Python 3.10+	wheel
Packagers	source archive

Verify downloads with the SHA256SUMS file published with the release.

DEB:

sudo apt install ./throttled_0.12.2_all.deb

On a running systemd host, the DEB enables and starts the service.

Fedora:

sudo dnf install ./throttled-0.12.2-1.noarch.rpm
sudo systemctl enable --now throttled.service

Alpine:

doas apk add --allow-untrusted ./throttled_0.12.2-1_noarch.apk
doas rc-update add throttled default
doas rc-service throttled start

The upstream APK is not repository-signed, which is why local installation requires --allow-untrusted.

The wheel installs the throttled command only. It does not install the privileged service, OS dependencies, or /etc/throttled.conf; end users should prefer a native package or the source installer.

Distribution packages

• Arch Linux: sudo pacman -S throttled
• Alpine edge/testing: doas apk add throttled
• Fedora: Copr package
• Gentoo: sudo emerge -av sys-power/throttled

Distribution packages are maintained independently and can lag behind the latest upstream release.

Install from source

Install Python 3.10 or newer, the Python virtual-environment tooling, git, kmod, pciutils, and UPower using your distribution package manager. Then:

git clone https://github.com/erpalma/throttled.git
cd throttled
sudo ./install.sh

The installer creates an isolated environment in /opt/throttled, preserves an existing /etc/throttled.conf, detects systemd, OpenRC, or runit, and enables the service. Use --init systemd|openrc|runit to override detection, or --no-start to install without enabling or starting it.

Configuration

The configuration file is /etc/throttled.conf. It contains separate [AC] and [BATTERY] profiles for power limits, update intervals, temperature targets, and experimental controls:

[GENERAL]
Enabled: True
Autoreload: True

[AC]
Update_Rate_s: 5
PL1_Tdp_W: 44
PL1_Duration_s: 28
PL2_Tdp_W: 44
PL2_Duration_S: 0.002
Trip_Temp_C: 95

[BATTERY]
Update_Rate_s: 30
PL1_Tdp_W: 29
PL1_Duration_s: 28
PL2_Tdp_W: 44
PL2_Duration_S: 0.002
Trip_Temp_C: 85

These are project defaults, not recommendations for every system. Check your processor limits and cooling capacity before changing them. The service reloads valid configuration changes automatically when Autoreload is enabled.

Undervolting and IccMax

Voltage offsets can be configured independently in [UNDERVOLT.AC] and [UNDERVOLT.BATTERY]. Only zero or negative millivolt values are accepted. Start at zero and test small changes under load; values stable on one CPU can crash another CPU of the same model.

Undervolting is disabled by firmware or microcode on many newer Intel systems. throttled cannot bypass a locked voltage interface.

IccMax values in [ICCMAX.AC] and [ICCMAX.BATTERY] are absolute current limits in amperes, not offsets. Inspect the system defaults with --monitor before enabling them.

Operation and diagnostics

Check the service:

systemctl status throttled.service
journalctl -u throttled.service -b

On OpenRC, use rc-service throttled status; on runit, use sv status throttled.

Monitor throttling causes and register values:

sudo throttled --monitor
sudo throttled --monitor 0.5
sudo throttled --debug

The monitor distinguishes thermal, power, current, and cross-domain limits. --debug reads back written values and prints CPU feature and thermal status information. Both commands run the control loop in the foreground, so stop the service first to avoid running two instances and press Ctrl+C when finished. Run throttled --help for all command-line options.

Requirements and known conflicts

• Linux on a supported Intel CPU.
• Python 3.10 or newer.
• Access to /dev/cpu/*/msr and /dev/mem.
• A kernel with CONFIG_X86_MSR and CONFIG_DEVMEM.
• dbus-fast, a running system D-Bus, UPower, modprobe, and setpci.
• Root privileges; containers, Flatpak, Snap, and AppImage sandboxes are not supported deployment targets.

Secure Boot commonly enables Kernel Lockdown, which can block the MSR and PCI BAR access required by throttled. Check the service log and /sys/kernel/security/lsm before changing security settings. Disabling Secure Boot or Kernel Lockdown reduces system protection and should be an informed, system-specific decision. Hardened kernels can deny /dev/mem access even without Lockdown.

thermald can conflict by applying its own RAPL or temperature policy. Do not disable it blindly: some platforms work better with thermald --adaptive. Compare monitoring output with each setup and keep the policy that behaves correctly on your hardware.

TLP only overlaps with throttled when the experimental HWP_Mode setting is enabled. In that case, disable TLP's CPU_ENERGY_PERF_POLICY_ON_* settings by assigning an empty string, as described in the TLP conflict guide. Avoid running multiple tools that continuously overwrite the same HWP/EPP policy.

Manufacturer utilities can persist quiet or power-saving profiles in firmware, so settings previously selected in another operating system may continue to limit performance after booting Linux.

If firmware does not repeatedly reset the limits, the kernel's intel_rapl interface may be sufficient and avoids a resident daemon. See the static RAPL alternative.

Updating and removal

For a native package, use the distribution package manager and review changes to /etc/throttled.conf after upgrading.

For a source installation:

cd throttled
git pull --ff-only
sudo ./install.sh

To stop and disable the service:

sudo systemctl disable --now throttled.service

OpenRC users can run sudo rc-service throttled stop followed by sudo rc-update del throttled default. Runit users can run sudo sv down throttled and remove the /var/service/throttled link. Remove native packages with the corresponding package manager.

Packaging and development

Build the Python wheel and source archive:

python3 -m pip install build
python3 -m build

Build all native package formats with nFPM:

./scripts/build-packages.sh

Use --packager deb, --packager rpm, or --packager apk to select a format. The lightweight DEB builder only requires dpkg-deb:

./scripts/build-deb.sh

See the packaging guide for the runtime and filesystem contract, dependency mapping, service lifecycle, and downstream packaging notes.

Run the test suite with:

python3 -m unittest discover -s tests

Bug reports and pull requests are welcome in the issue tracker.

Project history

The project was created for a firmware throttling problem seen on the 2018 Lenovo ThinkPad generation. It was originally installed as lenovo_fix and was renamed to throttled in 2021. Current installations use /etc/throttled.conf, the throttled command, and throttled.service.

License

throttled is available under the MIT License.