ubuntu 18 - extremely glitchy normally, works flawless with software rendering

[sona1111]

Hi All. I have own one of the 'duo' USB 3.0 monitors based on displaylink tech. I have ubuntu 18.04 with a number of alternative desktop environments available. When loading the standard ubuntu gnome desktop and installing dis displaylink driver, the monitor works, but it causes a large number of unbearable issues which occur on both the primary laptop screen and the displaylink device. The problem are like:

-the cursor constantly flickers, and will often come to rest in a state of not being displayed at all, so I will need to more the mouse to see it again.
-after moving the cursor I will see a animation of the cursor movement repeated across that part of the screen forever until I switch windows to clear the buffer.
-general stuttering on window switching and dragging.

Many of the other DE's did not work at all. I tried cinnamon DE, which worked but had the same glitchyness as ubuntu gnome.

Then I tried a selection called 'cinnamon (software rendering)'. Interestingly, this version work FLAWLESSLY completely great with all of the previous issues gone. Awesome! But the big issue here is that because it is software rendering, at least one CPU is always 100% busy and FPS is noticeably low in general. Trying to, for example, watch a youtube video causes cinnamon process to spike to 200% and can be laggy. So this way is also not really great, for a different reason!

I am guessing somehow the intel GPU rendering is writing to the buffer and them the displaylink painter is writing on top of that, causing a race condition, or something similar, between software and hardware rendering. But I am not an expert in these matters.

Is there any solution to this to use the standard rendering in cinnamon (or ubuntu gnome), while also fixing the glitchy behavior?

Thanks for reading.

Hardware: Thinkpad T70
Relevant $ lspci:

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 05)
00:02.0 VGA compatible controller: Intel Corporation Device 591b (rev 04)
00:08.0 System peripheral: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th Gen Core Processor Gaussian Mixture Model
00:16.0 Communication controller: Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1 (rev 31)

[KatarzynaCzaja]

Hello,

Thank you for reaching out to us!

Please follow the steps below and let me know if the issue has gone away:

Disable PageFlip for modesetting
It is preferred to keep using "modesetting" driver, but disabling page flipping is necessary.
To do this, as a root user create a file 20-displaylink.conf under:

/usr/share/X11/xorg.conf.d/

with the following content:

Section "Device"
  Identifier "DisplayLink"
  Driver "modesetting"
  Option "PageFlip" "false"
EndSection

A reboot is required for the setting to be effective.

Best regards,
Katarzyna

[sona1111]

Hi KatarzynaKowalczyk,

Thanks for the reply! I have tested this method on Cinnamon with HW rendering and I am pleased to say that the results seem to be much improved! Thank you very much for the resolve!

(there are still some flashing when hovering past some parts of windows, but it is miles better than it was)