>Psychtoolbox

PsychLinuxConfiguration([answers]) – Optimize setup of Linux system.

This script modifies system settings and configuration files
to optimize a Linux system for use with Psychtoolbox.

Currently it modifies files to allow to run Octave or Matlab
as regular non-root user, ie. without need for root login or
the “sudo” command. It does so by changing file permissions
and resource usage limits to allow a regular user application
to switch to realtime scheduling, lock its memory, and to
access special purpose hardware like GPUs, Bits+, Datapixx and
other research equipment.

Realtime optimizations are achieved by extending the
/etc/security/limits.conf file with entries that allow
members of the Unix user group “psychtoolbox” to lock
application memory into physical RAM, eliminating/minimizing
interference from the VM subsystem, and to run with realtime
priorities up to level 50. The group “psychtoolbox” is created
if it does not already exist.

If the target system has a /etc/security/limits.d/ directory,
then a separate rule file is stored to that directory to
achieve the change without messing around with the limits.conf
file.

root-less hardware access is achieved by copying a special
psychtoolbox.rules file into the /etc/udev/rules.d/ directory.
This udev rules file contains rules to auto-detect certain
hardware at bootup or when the hw is hot-plugged and to
reconfigure this hw or access permission for root-less access
by Psychtoolbox, and for optimal performance for the kind
of typical PTB use cases.

The script also creates a /etc/X11/xorg.conf.d/ directory for
xorg.conf configuration files which are writable by members
of the ‘psychtoolbox’ group to allow easy reconfiguration of
the X11 display system for running experiment sessions.

Additionally it configures the gpu’s to allow for display color
depths of more than 8 bpc. Furthermore, it configures a potentially
installed gamemoded daemon to further optimize cpu and graphics
performance for use with Psychtoolbox.

The script calls into the shell via “sudo” to achieve this
setup task, which itself needs admin privileges to modify
system files etc. “sudo” will prompt the user for his admin
password to complete the tasks.

The script also checks if any special configuration is required
to work around Linux specific OpenGL quirks of Matlab R2014b or
later.