Bug 436813

Summary:	"Present Windows" animation laggy on Wayland
Product:	[Plasma] kwin	Reporter:	smit <smit17xp>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	aleixpol, nate, smit17xp
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description smit 2021-05-09 06:58:38 UTC

SUMMARY

On wayland "Present Windows" animation is laggy. Its not that bad but noticeable compared to how smooth it is on xorg. I tried setting all Latency options in Compositor settings but still no change. other animations like wobbly windows seems to work fine.

On x11 session, running GPU heavy task in background and bunch of windows open, its still smooth compared to Wayland.

This problem did not occur when I tested 5.21.0. But I'm now on 5.21.5 and did not checked wayland in between so cant say which version this bug affects from.

STEPS TO REPRODUCE
1. Log into Wayland session.
2. Open more than 10 windows
3. toggle "Present Windows"

OBSERVED RESULT

laggy Animation

EXPECTED RESULT

smooth animation as x11

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: (available in About System)
KDE Plasma Version: 5.21.5
KDE Frameworks Version: 5.81.5
Qt Version: 5.15.2+kde+r192-1

ADDITIONAL INFORMATION

CPU: Intel i7-8565U (8) @ 4.600GHz
iGPU: Intel UHD Graphics 620
dGPU: Radeon 520 Mobile (muxless, uses iGPU to render)

tested on both GPUs by setting DRI_PRIME before `startplasma-wayland` command and getting same result

Comment 1 Nate Graham 2021-05-10 23:00:01 UTC

Cannot reproduce FWIW.

Comment 2 Vlad Zahorodnii 2021-05-11 07:24:03 UTC

On Wayland, we don't do triple buffering. This does make a difference with less powerful GPUs such as integrated Intel GPUs.

Comment 3 smit 2021-05-11 12:48:23 UTC

(In reply to smit from comment #0)
> This problem did not occur when I tested 5.21.0. But I'm now on 5.21.5 and
> did not checked wayland in between so cant say which version this bug
> affects from.

Sorry. This is not correct. I was using linu-zen(https://liquorix.net). I switched to vanilla linux-lts recently and that's when I noticed this issue. I'm again now on linux-zen and I can't notice stuttering/laggyness. Its still there if I closely look for it but its not that noticeable and it's completely gone (becomes smooth as x11) if I set Latency to the "Prefer smoother animations". So I can't say this started from 5.21.0.

Comment 4 Aleix Pol 2021-09-27 23:51:52 UTC

If changing kernels fixes the issue, then it clearly is an issue with the graphics driver you end up using.

There might be things we could do from KWin on it but it's rather limited as we are as good as the graphics drivers are anyway.

If you find any ideas why this could be report it and if we get to reproduce it maybe we have a chance at addressing it.