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LinuxGameMode - How to setup Linux performance optimizations via “gamemode”

You may have arrived here because Priority() instructed you to go here if
you want to enable a couple of extra performance optimizations for your
Linux system, to increase graphics and compute performance and further improve
realtime behaviour for demanding experimental paradigms.

The “gamemode” package is an optional Linux package, developed by the gaming
company “Feral Interactive”. It is meant to automatically optimize a Linux
system for high performance in demanding video games. Luckily for us, the same
optimizations that help high-end video games can also help the performance of
demanding psychophysics paradigms, especially for low-latency sound and hardware
input/output and high-performance graphics and visual stimulation.

When your script executes the Priority(n) command with a priority level n > 0,
ie. realtime priority, Psychtoolbox will check if the gamemode package is
installed and properly set up on your Linux system. If so, it will ask the
gamemode package to switch your Linux system into “Game mode”, until Priority(0)
is executed, clear Screen, clear mex, or clear all is executed, or Octave/Matlab
is quit.

Switching to gamemode should disable screen savers and screen lockers and various
power saving features which can impair performance. It will switch the cpu into
high-performance, high power consumption mode (by switching the cpu governor
to “performance” mode) for minimal processing latency and maximum speed. It will
give Psychtoolbox extra priority for any input/output, e.g., disc access or other
hardware access. Optionally, if set in a configuration file, it will enable
additional realtime scheduling optimizations on top of Psychtoolbox optimizations,
and optionally it will tune supported graphics cards for high performance mode,
e.g., all recent NVidia gpu’s with the proprietary driver, and all modern AMD
gpu’s with the amdgpu or amdgpu-pro open-source or hybrid drivers.

The “gamemode” package is not installed by default, but you can get recent
versions for some Ubuntu Linux distributions from the following sources:

For Ubuntu 20.04 LTS and later, as well as Debian 10 “Buster” and later,
gamemode is part of the distributions. It will get automatically installed if
you get Psychtoolbox from NeuroDebian or your distribution, or can be installed
via a simple command from the terminal window: sudo apt install gamemode

You can also download the very latest version of the gamemode package
source code, and compile and install it from its upstream source yourself:

https://github.com/FeralInteractive/gamemode

There you will also find documentation for extended setup of the package, e.g.,
an example .ini configuration file for additional performance tuning of gpu’s:

https://github.com/FeralInteractive/gamemode/blob/master/example/gamemode.ini

If you run PsychLinuxConfiguration it will offer you to install a gamemode.ini
file into your system which is already optimally set up for high-performance
use with Psychtoolbox.

Note that users of a multi-gpu system, e.g., a hybrid-graphics laptop, may need
to edit the /etc/gamemode.ini file manually after installation, as the config
file encodes the card number of the graphics card to optimize. On a dual-gpu
system, the default card number 0 may be wrong and would need to be changed
manually to 1 by you.

Note also that the default settings in the gamemode.ini file are not necessarily
optimal for some Intel integrated gpu’s, due to the shared thermal and power budget
for cpu and gpu. See https://github.com/FeralInteractive/gamemode/pull/179 for
a detailed discussion of the problem. There is a tunable parameter, called…
igpu_power_threshold=0.3
… which can be tweaked between 0.0 and 1.0 tune for your machine and workload,
although 0.3 is probably a reasonable default. See explanations in the .ini file.