QT 5.5 EGLFS performance on Raspberry PI 2

  • Setup : a rpi2 attached to a 1024x1080 monitor via HDMI.
    I have followed the tutorial from here.
    The compilation went fine and after a manual qt5 installation I started to build&test the samples .


    • overall the linuxfb performance is a lot better ( animatedtiles sample runs 2X faster)
    • an extreme example would be the lightning example which runs under 5-6 fps on eglfs and smooth on linuxfb.
    • on eglfs some qtquick samples like dynamicscene perform well.

    I tried the following without any noticeable difference:

    • set various QPA_EGLFS_XXX environment variables.
    • allocated 256 MB RAM to GPU.

    I do have some couple of questions
    Is this expected?
    is display size the problem?

    thank you in advance for any sort of advice/tipp

  • linuxfb is good for QWidgets, eglfs - for QtQuick.

    "animatedtiles" and "Lighting Effect Example" (they are QWidgets) theoretically may perform worse on eglfs than on linuxfb because eglfs works through the GLES 3D acceleration that is useless for simple widgets.

    linuxfb isn't using GLES, so QtQuick doesn't work there. (until complete software rendering is released)

  • Thank you for the answer:)
    In the meanttime I got the Raspebrry Pi 7" Display (800x480) and the Widgest's performance on eglfs seems a lot better. - it looks like the display size ( or the display interface ??) plays a major role.
    Basically I have an QT4 QWidgets app that I want to migrate to Qt5 / Declarative . As a first step , I want to replace the frontend navigation UI with some QML based component.
    The only way to achieve this is on the actual test device is eglfs but it needs to support the QWidgets well enough .
    The app contains some data aquisition&visualization (QWT) part, that is very performance sensitive, and I actually hoped that eglfs would increase performance ....and this is why I was pretty dissapointed with the first tests restults.
    So I am really interesed about the limitations and the bigger overview.

    • Is it possible on EGLFS to embbed a QML scene in a QWidget?

    • Is a better Wayland better platform ( for rpi2 that is) for what I want to achieve?

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