amd-disable-c6

This is a systemd service to automatically disable the C6 power saving state on AMD Zen (Ryzen / Epyc) processors. The C6 state is known to occasionally freeze Linux distributions running Zen-based processors in deep idle. This systemd service disables the C6 state on boot as a workaround for this bug. Of course, this is only a stop-gap solution until AMD releases a final fix to the underlying issue.

Installation

RPM and DEB repositories for the service are available to be used for apt/dnf/yum/zypper.
Note: On RPM-based distros you will have to enable and start the service after installation using:

$ sudo systemctl enable amd-disable-c6.service
$ sudo systemctl start amd-disable-c6.service

Supported Distributions at the moment:

• RPM: CentOS 7 and 8, Fedora 28, 29, 30 and Rawhide, Mageia 7 and Cauldron, openSUSE Tumbleweed, openSUSE Leap 15 and 15.1, RHEL 7 and 8, SLE 15 and 15.1
• DEB: Debian 9 and 10, Ubuntu 16.04, 18.04, 18.10 and 19.04

How to build and install manually:

$ sudo make install
$ sudo systemctl enable amd-disable-c6.service
$ sudo systemctl start amd-disable-c6.service

Troubleshooting

The most likely reason for the service to fail is the msr module not being present. It should be present on most distros, but some (e.g., Arch, Manjaro) do not have it enabled by default.

To enable the module:

$ sudo modprobe msr #enable until next reboot
$ sudo sh -c "echo msr > /etc/modules-load.d/msr.conf" #auto-enable at boot time