we are experiencing timing problems on our Dell XPS13 Laptop (Developer edition) running Ubuntu 18.04.5 LTS
Psychtoolbox does not issue any warnings/errors, and the typical tests run fine (e.g. VBLSyncTest). The only thing I noticed is that if I run the VBLSyncTest for longer times, e.g. 10 minutes, Linux suddenly shows a login screen after some time despite the maximum priority set within the script.
Once we start the actual experimental code (which works perfectly on our stationary Linux machines), there appear to be many lost frames as measured by examining the StimulusOnsetTime returned by the [~, stimulusOnset, missed] = Screen(‘Flip’, ptb.w.id); command, and the trials, that are based on frame loops, take up to 1500 ms longer than expected.
We have configured the x-screens and installed the lowlatency kernel. The last thing to try seems to be installing GameMode, but I just wanted to double-check with experts here that I am not missing something obvious. We never had to use the GameMode before on Linux and always had satisfactory timing with this same code.
Many thanks in advance!
Below is the system information:
ans = 3.0.17 - Flavor: Debian package - psychtoolbox-3 (22.214.171.124.dfsg1-1~nd18.04+1)
Which platform (Mac OS X, Windows XP/Vista/7, Linux, …) AND which MATLAB/Octave version you are using?
Ubuntu 18.04.5 LTS
A minimal code snippet that exhibits the issue you are having, please format the code with the preformatted text tool provided by the forum software, or use markdown fenced code blocks .
Too embarrassing to post, but nothing fancy that wold result in frame losses.
- Warnings and Errors that were printed to the console ( please read them carefully , they may contain advice on how to solve your problem!)
PTB-INFO: This is Psychtoolbox-3 for GNU/Linux X11, under GNU/Octave 64-Bit (Version 3.0.17 - Build date: Jan 22 2021).
PTB-INFO: OS support status: Linux 5.4.0-66-lowlatency Supported.
PTB-INFO: Type ‘PsychtoolboxVersion’ for more detailed version information.
PTB-INFO: Most parts of the Psychtoolbox distribution are licensed to you under terms of the MIT License, with
PTB-INFO: some restrictions. See file ‘License.txt’ in the Psychtoolbox root folder for the exact licensing conditions.
PTB-INFO: For information about paid priority support, community membership and commercial services, please type
PTB-INFO: OpenGL-Renderer is Intel Open Source Technology Center :: Mesa DRI Intel(R) UHD Graphics (CML GT2) :: 3.0 Mesa 20.0.8
PTB-INFO: VBL startline = 2160 , VBL Endline = -1
PTB-INFO: Will try to use OS-Builtin OpenML sync control support for accurate Flip timestamping.
PTB-INFO: Measured monitor refresh interval from VBLsync = 16.668124 ms [59.994753 Hz]. (50 valid samples taken, stddev=0.003058 ms.)
PTB-INFO: Reported monitor refresh interval from operating system = 16.667778 ms [59.995998 Hz].
PTB-INFO: Small deviations between reported values are normal and no reason to worry.
PTB-INFO: Psychtoolbox imaging pipeline starting up for window with requested imagingmode 1027 …
PTB-INFO: Will use 8 bits per color component framebuffer for stimulus drawing.
PTB-INFO: Will use 8 bits per color component framebuffer for stimulus post-processing (if any).
PTB-INFO: Failed to request additional performance tuning from operating system.
PTB-INFO: This is because the optional “FeralInteractive gamemode” package is not installed
PTB-INFO: and set up yet. If you want to have these extra optimizations, then read
PTB-INFO: the setup instructions in “help LinuxGameMode”.
- Hardware setup (GPU etc.) and relevant driver versions.
Intel® Core™ i7-10510U CPU @ 1.80GHz × 8
Intel® UHD Graphics (CML GT2)