Bug 380978

Summary:	Plasma desktop not rendering in 144FPS
Product:	[Plasma] kwin	Reporter:	Martin <spleefer90>
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	taocrismon
Priority:	NOR
Version First Reported In:	5.10.1
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	qdbus org.kde.KWin /KWin supportInformation xrandr -q pacman -Q (list of all installed packages)

Description Martin 2017-06-08 16:44:52 UTC

Created attachment 105990 [details]
qdbus org.kde.KWin /KWin supportInformation

Discussed here too - https://www.reddit.com/r/kde/comments/6fznb3/plasma_desktop_not_rendering_in_144fps/

I have 2 monitors, both are 1920x1080, one of them is 144Hz, one 60Hz.

In Plasma, both monitors are rendering in 60Hz.
When I launch a game like Dota 2 and move windows around on top of the game, they're rendered in 144Hz.

I worked around this by adding 

[Compositing]
MaxFPS=144.0

To kwinrc.

Comment 1 Martin 2017-06-08 16:45:20 UTC

Created attachment 105991 [details]
xrandr -q

Comment 2 Martin 2017-06-08 16:45:49 UTC

Created attachment 105992 [details]
pacman -Q  (list of all installed packages)

Comment 3 Martin Flöser 2017-06-17 12:21:58 UTC

A system with two different refresh rates cannot be properly supported on X11. The compositor uses one window and that gets rendered to both screens. It is quite likely that the X server restricts the refresh rate to the least common denominator, which would make sense.

As there is a workaround by forcing the FPS, this looks fine to me.