Bug 441288

Summary:	Weird stuttering
Product:	[Plasma] kwin	Reporter:	d3coder <admin>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	aleixpol, nate
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description d3coder 2021-08-21 11:21:35 UTC

SUMMARY
I have weird stuttering on force lowest latency on wayland.
This does not happen on X11
This does not happen when i have Show FPS effect enabled


STEPS TO REPRODUCE
1. Start Wayland session
2. Select force lowest latency
3. Move settings window
4. Go to effects and enable Show FPS effect
5. Try to move settings window again

OBSERVED RESULT
Weird stuttering (dropped frames?)
No stuttering after Show FPS effect enabled

EXPECTED RESULT
No stuttering

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.22.4
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.2
Kernel Version: 5.13.12-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-4790K CPU @ 4.00GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 4600

ADDITIONAL INFORMATION
I have 2 monitors
Happens with 5.22.4 too

Built from master today:
kdecoration-git 5.22.80_r268.g1dabf57-1
kwayland-git 5.86.0_r1106.g41bed39-1
kwayland-server-git v5.21.90.r46.g671d70dc-1
kwin-git 5.22.80_r19807.g17b161213-1
plasma-wayland-protocols-git r1028.8d33090-1

Comment 1 d3coder 2021-11-23 20:21:54 UTC

I did more research. 

1. Start Firefox wayland (MOZ_ENABLE_WAYLAND=1 firefox-developer-edition)
2. Open this page: https://webglsamples.org/aquarium/aquarium.html
3. It shows 30 FPS
4. Enable "Show FPS" effect
5. This page now shows 60 FPS
6. Disable effect
7. It drops back to 30 FPS

Operating System: Arch Linux
KDE Plasma Version: 5.23.3
KDE Frameworks Version: 5.88.0
Qt Version: 5.15.2
Kernel Version: 5.15.4-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-4790K CPU @ 4.00GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 4600

Comment 2 Aleix Pol 2022-07-28 14:55:09 UTC

I cannot reproduce at all, I'd say it might be that it got fixed as it all has changed a lot over time.

Note having higher fps when the effect is on, could just mean that firefox doesn't request issuing frames that often.