Bug 452657

Summary:	[kwin_wayland] 100% cpu usage after user switching
Product:	[Plasma] kwin	Reporter:	c56w1t63
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	buddha, c56w1t63, nate, notmart, smirky
Priority:	NOR
Version First Reported In:	5.24.4
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	gdb backtrace

Description c56w1t63 2022-04-15 12:14:44 UTC

SUMMARY
After user switching kwin_wayland on 100% cpu usage

STEPS TO REPRODUCE
1. kwin_wayland session in user A
2. switch to user B

OBSERVED RESULT
Often 1 cpu core is on 100% from process of user A:
/usr/bin/kwin_wayland --wayland-fd 5 --socket wayland-0 --xwayland-fd 6 --xwayland-fd 7 --xwayland-display :1 --xwayland-xauthority /run/user/1001/xauth_zJPcnB --xwayland

If I switch back to user A the cpu usage is back to normal, but sometimes kwin_wayland from user B is up to 100% again and vice verca.

EXPECTED RESULT
Normal cpu usage

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.93.0
Qt Version: 5.15.3
Kernel Version: 5.17.3
Graphics Platform: Wayland

ADDITIONAL INFORMATION

Comment 1 Marco Martin 2022-04-19 13:59:49 UTC

can you on the active session do gdb attach (the pid of the *other* running kwin, not the one which is rendering on the screen at the moment)

at that point you can do ctrl+c and then bt to obtain a backtrace to see where it was at that moment

Comment 2 Marco Martin 2022-04-19 14:05:50 UTC


*** This bug has been marked as a duplicate of bug 452726 ***

Comment 3 c56w1t63 2022-04-19 14:54:08 UTC

Created attachment 148244 [details]
gdb backtrace

sudo gdb -pid 3332 -batch -ex "set logging file kwin_wayland.gdb" -ex "set logging on" -ex "continue" -ex "thread apply all backtrace" -ex "quit"

Comment 4 c56w1t63 2022-05-01 14:28:32 UTC

Any ideas? Because I can't work with multi user logged in as the cpu and fan usage is really high then.