AMDGPU Clocks

Introduction

This is a simple script that can be used to set custom power states for recent AMD GPUs that are driven by amdgpu Linux kernel driver. The script is able to set custom clocks, voltages and some other power states, assuming that Radeon OverDrive is enabled in kernel boot opions. The OverDrive is not enabled by default as of Linux 5.x, it can be enabled by setting 14th bit (0x4000) of a ppfeaturemask amdgpu driver to 1. For example, setting amdgpu.ppfeaturemask=0xfffd7fff or amdgpu.ppfeaturemask=0xffffffff kernel boot option will do the trick. This would enable amdgpu driver sysfs API that allows fine grain control of GPU power states (GPU & VRAM clocks & voltages, depending on the actual hardware). It should work on Polaris, Vega (unfortunately Vega found on AMD APUs does not expose this API), Navi and RDNA cards, and it can be used to easily manage multiple AMD graphics cards.

How does it work

By default, custom power states for a particular GPU can be defined in /etc/default/amdgpu-custom-state.cardX file, which is expected to be created by user, and where X corresponds to a card in /sys/class/drm/cardX. The custom state file have same format as the actual /sys/class/drm/cardX/device/pp_od_clk_voltage, with option to add newlines, comments (lines starting with #) and few additional parameters used to set extra power state parameters. These are FORCE_SCLK & FORCE_MCLK, that can be used to limit GPU and memory power states to a particular subset of states, FORCE_POWER_CAP that can be used to set desired power cap, FORCE_PERF_LEVEL that can be used to force desired power_dpm_force_performance_level for a card (which can be auto, low, high, manual, etc) and FORCE_POWER_PROFILE used for manually setting the profile found in card's pp_power_profile_mode.

Since some Linux kernel versions are known to enumerate the very same card to a different cardX identifier (X randomly toggles between 0 or 1 on reboot), one can alternatively define the custom state using /etc/default/amdgpu-custom-state.pci:xxxx:xx:xx.x file instead, where xx:xx.x corrsponds to intended card's PCI <domain>:<bus>:<dev>.<function> numbers. For example /etc/default/amdgpu-custom-state.pci:0000:03:00.0.

Here is an example how custom power state file may look like for Polaris cards:

$ cat /etc/default/amdgpu-custom-states.card0
# Set custom GPU states 6 & 7:
OD_SCLK:
6:       1000MHz        860mV
7:       1050MHz        890mV
# Set custom memory states 1 & 2:
OD_MCLK:
1:        900MHz        800mV
2:       1600MHz        900mV
# Only allow SCLK states 5, 6 & 7:
FORCE_SCLK: 5 6 7
# Force fixed memory state:
FORCE_MCLK: 2
# Force power limit (in micro watts):
FORCE_POWER_CAP: 90000000
# In order to allow FORCE_SCLK & FORCE_MCLK:
FORCE_PERF_LEVEL: manual

Here is an example how custom power state file may look like for Navi cards:

# For Navi (and Radeon7) we can only set highest SCLK & MCLK, "state 1":
OD_SCLK:
1: 1550MHz
OD_MCLK:
1: 750MHz
# More fine-grain control of clocks and voltages are done with VDDC curve:
OD_VDDC_CURVE:
0: 800MHz @ 800mV
1: 1125MHz @ 820mV
2: 1550MHz @ 850mV
# Force power limit (in micro watts):
FORCE_POWER_CAP: 87000000
FORCE_PERF_LEVEL: manual

Here is an example how custom power state file may look like for RDNA2 cards:

OD_VDDGFX_OFFSET:
-75mV
FORCE_PERF_LEVEL: manual
FORCE_POWER_CAP: 99000000

Installing and manually running the script

Simply place the script in /usr/local/bin/amdgpu-clocks:

sudo ln -s $(pwd)/amdgpu-clocks /usr/local/bin/amdgpu-clocks

and specify custom power states in /etc/default/amdgpu-custom-states.card0:

$ sudo amdgpu-clocks

Detecting the state values at /sys/class/drm/card0/device/pp_od_clk_voltage:
  SCLK state 0: 700Mhz
  SCLK state 1: 2539Mhz
  MCLK state 0: 97Mhz
  MCLK state 1: 1000MHz
  VDD GFX Offset: 0mV
  Maximum clocks & voltages:
    SCLK clock 3150Mhz
    MCLK clock 1200Mhz
  Curent power cap: 130W
Verifying user state values at /etc/default/amdgpu-custom-state.card0:
  VDD GFX Offset: -75mV
  Force performance level to manual
  Force power cap to 99W
Committing custom states to /sys/class/drm/card0/device/pp_od_clk_voltage:
  Done

The script can also be invoked with specific custom state file prefix (can be a directory, case trailing slash is supplied), for example:

$ sudo USER_STATES_PATH=custom-states amdgpu-clocks

This will load and apply custom states from all custom-states.card* files in the current directory. Script can also be used with an additional 'restore' parameter that can be used to restore all states to the initial defaults (states before script was executed for the first time), with exception of pp_power_profile_mode which will be set to 0.

Making the custom power states persist

This can be achieved by placing provided systemd service file in /etc/systemd/system/ directory, and enable it:

$ sudo systemctl enable --now amdgpu-clocks

However, if your system goes to suspend state, the above service will not auto-restart (due to RemainAfterExit parameter). To fix that copy provided file into /usr/lib/systemd/system-sleep

$ cp amdgpu-clocks-resume /usr/lib/systemd/system-sleep/

Of course, one should not forget to place the actual custom power states in /etc/default/amdgpu-custom-state.cardX.