Bug 449398

Summary:	Non-Qt/KDE apps stutter / have rendering issues under Wayland
Product:	[Plasma] kwin	Reporter:	Viorel-Cătălin Răpițeanu <rapiteanu.catalin>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	major	CC:	kde, miranda
Priority:	NOR
Version First Reported In:	master
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	The video playback rendering is not sequential.

Description Viorel-Cătălin Răpițeanu 2022-01-31 00:27:30 UTC

SUMMARY
When using Wayland with the Nvidia proprietary driver, all non-Qt/KDE apps stutter to a point that makes them unusable. This is extremely visible when the application does some playback (like playing a video in Firefox) or typing something in a box (like the Matrix chat Element).
It seems that instead of rendering the next frame, for a split second the previous frame is being rendered and only then the correct frame is being drawn. For example, if you have in a text box the word "hell", when you type the last "o", sometimes, the word drawn will be "hel" and only a bit afterwards you will see the full "hello" word.

STEPS TO REPRODUCE
1. Start a Wayland session with the Nvidia proprietary driver.
2. Start any type of non-Qt/KDE application (like Element chat).
3. Type a message.

OBSERVED RESULT
The rendered frames are not sequential.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Plasma master (Wayland session)
KDE Plasma Version: 5.23.90 master
KDE Frameworks Version: 5.91 master
Qt Version: 5.15.2
Video Driver: nvidia 495.46, egl-wayland 2:1.1.9-master, xorg-xwayland master 21.1.2.901.r270

Comment 1 Viorel-Cătălin Răpițeanu 2022-01-31 00:29:51 UTC

Created attachment 146091 [details]
The video playback rendering is not sequential.

The video used in the clip: https://www.youtube.com/watch?v=cWmURg_rM2o&t=7s

Note: The same video plays correctly under X11.

Comment 2 miranda 2022-05-27 18:04:12 UTC

I'll throw my hat in the ring and mention this is still a problem in the 5.25 beta. Scrolling in Firefox in a wayland session is an easy reproduction step. Confirmed on two separate machines (GTX 970 and GTX 2080 Super, multi-monitor respectively), same exact behavior.

plasmashell: 5.24.90
KDE Frameworks: 5.94.0
Qt: 5.15.4
Nvidia: 515.43.04
xwayland: 22.1.2

Comment 3 miranda 2022-05-27 18:21:46 UTC

Note by "still a problem in" I don't necessarily mean "still a problem with". This may very well be upstream. :)

Comment 4 David Edmundson 2023-03-24 00:07:39 UTC

Problems with xwayland and Nvidia are known.