Pi400 performance issues in desktop environments using Manjaro minimal 20.12.1

I tried to setup gnome, and then kde with wayland (after gnome seemed like a lost cause from the performance issues) from a minimal manjaro install. My pi400 itself was setup with the pi4-rc kernel and headers, mesa, and dtoverlay=vc4-kms-v3d-pi4 set in my /boot/config.txt for the v3d renderer. For the desktop environments, I followed the arch wiki article on wayland to make sure I wasn’t overlooking any GUI libraries or environment variables to set for wayland. I also checked the gnome and kde articles to make sure I wasn’t overlooking anything for wayland as well.

In gnome specifically, it actually ran reasonably well, but some applications had visual glitching. glxgears for example looked visually glitched out, with a scrambled mess taking place of the gears, though it did continue with providing performance output (which was actually roughly what I expect when it is properly working), and mpv video playback appearing in the same scrambled manner. Tried to tinker around but couldn’t figure anything out so decided to install plasma-desktop and plasma-wayland-session. I use the manjaro kde pi release 20.10 in wayland so I know the performance on the pi is amazing.

Surprisingly though, kde performed worse than gnome. The plasma UI was incredibly sluggish, but programs like glxgears and firefox worked perfectly fine and speedy, with no visual glitching what so ever. I set desktop compositing to opengl 3.1 since v3d supports it, but no improvement. Completely baffled at this one since the manjaro kde pi image runs great.

I’m wondering what I might be overlooking when it comes to setting up KDE from scratch on the minimal installation to get it running just as well as the manjaro kde pi release. I have a feeling gnome is a lost cause at the moment. Would really appreciate any help on this one! Thanks.

In our plasma edition we turn off Blur and Contrast effects in Plasma Desktop Effects. These have a huge impact on UI performance, so try that. :slight_smile:

We also set QT_QUICK_BACKEND=software in /etc/environment, because the 3d acceleration of the hardware is not quite good enough yet. But that should be present in the minimal images too.

this was it! thank you very much.

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Is hardware acceleration still too slow, with Mesa 20.3.2 on the RPi4?

I haven’t tested it since mesa 20.3 release. I’ll do that. :slight_smile:

what would the value be for hardware acceleration if we wanted to try that?

I just tested it on my Raspberry Py 400 and it seems to work really well. Plasma is smooth and snappy with hardware accelerated desktop enabled. :slight_smile:


what’s the value to set for QT_QUICK_BACKEND for hardware acceleration? I looked up some documentation but really couldn’t find a satisfactory option for raspberry pi

Just remove it. :slight_smile:

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