Bug 370179

Summary:	UnrealEngine 4 Editor popups cause the ui to lag with kwin_x11
Product:	[Plasma] kwin	Reporter:	salamanderrake <salamanderrake>
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal
Priority:	NOR
Version First Reported In:	5.8.0
Target Milestone:	---
Platform:	Neon
OS:	Linux
URL:	https://www.youtube.com/watch?v=0IBzBzFLO6I
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description salamanderrake 2016-10-06 06:38:47 UTC

Using UE4Editor( UnrealEngine 4 Editor) with the pop-ups smearing and sever lag in the node(blueprints) editor window.

Reproducible: Always

Steps to Reproduce:
1. Build Editor
2. Run Editor
3. Hover over items to get pop up, and drag variables from the left pane onto the blueprint region and watch it lag.

Actual Results:  
Pop-ups and dragged objects cause sever lag in the UI.

Expected Results:  
Pop-ups come and go with no issue, no UI lag in the editor.

Comment 1 Martin Flöser 2016-10-06 06:41:44 UTC

Please provide output of:
qdbus org.kde.KWin /KWin supportInformation

when the problem is visible.

Comment 2 salamanderrake 2016-10-06 06:46:44 UTC

Perf:
https://dl.dropboxusercontent.com/u/71062164/UnrealEngine/Perf.tar.xz

xtrace:
https://dl.dropboxusercontent.com/u/71062164/UnrealEngine/xtrace-logs.tar.xz

Comment 3 Christoph Feck 2016-10-07 02:19:41 UTC

If you can provide the information in requested in comment #1, please add it.

Comment 4 salamanderrake 2016-10-07 02:28:45 UTC

This is before UE4Editor starts:
https://gist.github.com/salamanderrake/319407e000873a944dea19ddaede5e24

This is after UE4Editor starts:
https://gist.github.com/salamanderrake/e841f3ddcf8a0e0b5e0fe8daa52acd6b

The problem is that UE4Editor is shutting off the compositor for the window manager when it gets better performance with the compositor enabled. Its a game engine with an editor built on top of it, so the wm or the internal code causes it to shut off the wm composite manager. I may just close this as its not an issue on your end.

Comment 5 Martin Flöser 2016-10-07 05:44:42 UTC

As the problem is with pure non-composited setup it's not a bug in our system. In case you have intel hardware consider switching to the modesettings xorg module. Otherwise consider creating a window specific rule to disallow this window to block compositing.

Comment 6 salamanderrake 2016-10-07 14:50:41 UTC

How do I create a window specific rule?

Comment 7 salamanderrake 2016-10-07 15:04:49 UTC

Nevermind I found the option.