Bug 485424

Summary: Fullscreen games have a choppy visual framerate ~ last good commit a4be9859b72b9aaa8b6a9a9b4bdb413ea987ab2d
Product: [Plasma] kwin Reporter: Kyle Devir <kyle.devir>
Component: generalAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: kyle.devir, robert.wolniak, xaver.hugl
Priority: NOR    
Version First Reported In: git master   
Target Milestone: ---   
Platform: Compiled Sources   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Kyle Devir 2024-04-12 09:34:58 UTC 
SUMMARY
Fullscreen games have a consistent choppy visual framerate, irrespective of the actual framerate. Displayed framerate returns to what is expected when the game is windowed instead. Fullscreen games run in Gamescope via virtual terminal have an expected visual framerate.

That is, despite having tens of FPS, the game visually runs as if it has 5 FPS per second.

The last time games ran fullscreen at the visually expected framerate was on my Git build on the 30th of March.

Tested Dragon's Dogma: Dark Arisen and Monster Hunter World. Consistent results.

STEPS TO REPRODUCE
1. Run any game at fullscreen ~ enabled Steam FPS counter.
2. Change the game to windowed mode.
3. Observe the differences in visual smoothness.

OBSERVED RESULT
Choppy visual framerate that doesn't match the framerate number.

EXPECTED RESULT
Smooth visuals as expected of the observed framerate.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.0.80
KDE Frameworks Version: 6.1.0
Qt Version: 6.7.0
Kernel Version: 6.9.0-rc3-1-custom-bcachefs-git-g3b2de7f7d7ef (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor
Memory: 15.5 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7B85
System Version: 1.0

ADDITIONAL INFORMATION
Comment 1 Kyle Devir 2024-04-12 10:18:35 UTC 
Sigh, and now I can't reproduce it... :|

Well, let's see if anything happens in future.
Comment 2 Kyle Devir 2024-04-26 05:00:35 UTC 
Sigh, it's come back again, and I'm not even sure where to start with bisecting, as bisecting didn't yield anything for me last time. It just spontaneously started working again, and I didn't know why.

And now the same stuttering is back... :|

If there is any other way I can debug this, I'd be happy.
Comment 3 Kyle Devir 2024-04-26 05:19:43 UTC 
Actually... seems like Adaptive Sync might be the issue. If I turn it off, then the game presents normally...
Comment 4 Robert Wolniak 2024-04-26 17:54:26 UTC 
I have the same issue on openSUSE Tumbleweed and disabling adaptive sync also seemed to have fixed the issue.

RX 6600 and Wayland session. I am also happy to debug it if necessary!
Comment 5 Zamundaaa 2024-04-26 18:23:49 UTC 
This sounds a bit like bug 485730. What KWin version / commit are you on? On git master, running RDR2 with adaptive sync, there's no stutter
Comment 6 Robert Wolniak 2024-04-26 18:28:17 UTC 
(In reply to Zamundaaa from comment #5)
> This sounds a bit like bug 485730. What KWin version / commit are you on? On
> git master, running RDR2 with adaptive sync, there's no stutter

Thank you for your reply. From what I can see, it is indeed 6.0.4.

For now I downgraded to 6.0.3 and I don't have such issues.
Comment 7 Kyle Devir 2024-04-27 05:26:44 UTC 
(In reply to Zamundaaa from comment #5)
> This sounds a bit like bug 485730. What KWin version / commit are you on? On
> git master, running RDR2 with adaptive sync, there's no stutter

Currently, 48197a4f5be12cb0aadad0cd3b090890a59fca60

I'll rebuild with current master, and see if I can reproduce
Comment 9 Kyle Devir 2024-04-27 13:48:56 UTC 
Seems to be fixed in KWin master. Will close. :)