Bug 485067

Summary: [Nvidia] High cpu usage of kscreenlocker_greet and plasmashell processes after switching users
Product: [Plasma] plasmashell Reporter: Vadym Krevs <vkrevs>
Component: Screen lockingAssignee: Plasma Bugs List <plasma-bugs-null>
Status: REPORTED ---    
Severity: normal CC: Geir.Horn, kdedev, MeSat, nate
Priority: NOR    
Version First Reported In: 6.2.4   
Target Milestone: 1.0   
Platform: openSUSE   
OS: Linux   
See Also: https://bugs.kde.org/show_bug.cgi?id=347772
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: qdbus-qt5 org.kde.KWin /KWin supportInformation
perf report for the plasmashell process with high CPU usage
qdbus-qt5 org.kde.KWin /KWin supportInformation
qdbus6 org.kde.KWin /KWin supportInformation

Description Vadym Krevs 2024-04-05 07:12:20 UTC
Created attachment 168172 [details]
qdbus-qt5 org.kde.KWin /KWin supportInformation

SUMMARY
High cpu usage of  kscreenlocker_greet and plasmashell  processes after switching users.

Originally reported via https://bugs.kde.org/show_bug.cgi?id=347772#c75, created a new issue as requested by Nate in https://bugs.kde.org/show_bug.cgi?id=347772#c77.

Reproducible: Always. 
Started to happen after replacing the old AMD video card with the NVIDIA video card.

Steps to reproduce:
1. Login as user1
2.  Switch user to user2
3. Observe kscreenlocker_greet and plasmashell processes running as user1 begin to consume 100% CPU.
4. Log off user2 and log back in as user1.
5. High CPU usage disappears.

The workaround from https://bugs.kde.org/show_bug.cgi?id=347772#c22 does not help.
Output of "qdbus-qt5 org.kde.KWin /KWin supportInformation" is attached.


SOFTWARE/OS VERSIONS
Operating System: openSUSE Leap 15.5
KDE Plasma Version: 5.27.11
KDE Frameworks Version: 5.115.0
Qt Version: 5.15.12
Kernel Version: 5.14.21-150500.55.52-default (64-bit)
Graphics Platform: X11
Graphics Processor: NVIDIA GeForce RTX 4060 Ti/PCIe/SSE2
Nvidia drivers: nvidia-video-G06-550.67-lp155.20.1.x86_64)
Comment 1 Vadym Krevs 2024-04-05 07:13:01 UTC
Output of the following is attached.
perf record -p $(pidof plasmashell) -e cpu-cycles --call-graph fp
perf report > perf.report
Comment 2 Vadym Krevs 2024-04-05 07:13:33 UTC
Created attachment 168173 [details]
perf report for the plasmashell process with high CPU usage
Comment 3 TraceyC 2025-01-14 01:22:00 UTC
*** Bug 486788 has been marked as a duplicate of this bug. ***
Comment 4 Nate Graham 2025-05-09 17:33:55 UTC
Thank you for the bug report! I'm so sorry we weren't able to get to it yet, especially given the debugging you've already done.

However I can't reproduce this on my system running git master. Can you check and see if it's still an issue in Plasma 6.3.5 or later? Thanks a lot!
Comment 5 Vadym Krevs 2025-05-10 10:56:13 UTC
Still an issue on:
Operating System: openSUSE Leap 15.6
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.0
Kernel Version: 6.4.0-150600.23.47-default (64-bit)
Graphics Platform: X11
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 125.7 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 4060 Ti
Manufacturer: ASUS

Outputs of  "qdbus-qt5 org.kde.KWin /KWin supportInformation" and "qdbus6 org.kde.KWin /KWin supportInformation"  are attached.
Comment 6 Vadym Krevs 2025-05-10 10:56:47 UTC
Created attachment 181131 [details]
qdbus-qt5 org.kde.KWin /KWin supportInformation
Comment 7 Vadym Krevs 2025-05-10 10:57:11 UTC
Created attachment 181132 [details]
qdbus6 org.kde.KWin /KWin supportInformation
Comment 8 Robin Laing 2025-12-12 07:43:41 UTC
Had similar issues.  Changed from sddm to gdm and problem lessened.  Changed video card with more vram have not had an issue since.  I did read an article about sddm not working well with Wayland and I had used gdm before.  

Can now have at least three sessions running with no issues.  

Check amount of vram that is being used.  I am finding that over 1Gig of Vram is required for each session.  Looking at a remote machine that is in power saving mode, vram is about 1.6Gig for a single session.  Kscreenlocker is using 286MiB of that session.
Comment 9 Vadym Krevs 2025-12-12 08:56:08 UTC
(In reply to Robin Laing from comment #8)
> Had similar issues.  Changed from sddm to gdm and problem lessened.  Changed
> video card with more vram have not had an issue since.  I did read an
> article about sddm not working well with Wayland and I had used gdm before.  
> 
> Can now have at least three sessions running with no issues.  
> 
> Check amount of vram that is being used.  I am finding that over 1Gig of
> Vram is required for each session.  Looking at a remote machine that is in
> power saving mode, vram is about 1.6Gig for a single session.  Kscreenlocker
> is using 286MiB of that session.

I'd expect 16gb of vram on my 4060 ti should have been sufficient ...