Bug 428830

Summary: App responds very slowly to any input on Wayland
Product: [Applications] plasma-systemmonitor Reporter: Matej Mrenica <matejm98mthw>
Component: generalAssignee: KSysGuard Developers <ksysguard-bugs>
Status: RESOLVED FIXED    
Severity: normal CC: ahiemstra, eric1, fabian, matejm98mthw, plasma-bugs
Priority: NOR    
Version: unspecified   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed In: Plasma 5.21
Sentry Crash Report:

Description Matej Mrenica 2020-11-08 10:26:52 UTC 
SUMMARY
For example, just hover over something in the left panel and wait for the highlight to activate, it takes multiple seconds (~7). Also the entire app refreshes at ~1 fps or less, doesn't maximize, and stops responding (greys out) often.

Plasma 5.20.2, Qt 5.15.1, KF 5.75, Wayland only
Comment 1 Eric Armbruster 2020-11-08 10:51:14 UTC 
I can confirm this on Wayland as well.

Operating System: Arch Linux
KDE Plasma Version: 5.20.2
KDE Frameworks Version: 5.75.0
Qt Version: 5.15.1
Kernel Version: 5.9.6-arch1-1
Comment 2 Arjen Hiemstra 2020-11-08 13:39:55 UTC 
What kind of GPU are you running on? We do nothing special that should slow things down on Wayland, but the charts are all rendered by the GPU which might cause slowdowns in some cases.

Also, have you checked whether the same happens on X?
Comment 3 Matej Mrenica 2020-11-08 18:07:44 UTC 
I have a AMD Vega 8 GPU inside a Ryzen 5 3550H. This issue is not present in X.org session, only in Wayland.
Comment 4 Matej Mrenica 2020-11-08 18:16:12 UTC 
I also tested this on a different laptop with Manjaro and I got the same behavior.
The other system has a Intel Haswell GPU, so it's not something like this: https://bugs.kde.org/show_bug.cgi?id=424398
Comment 5 Arjen Hiemstra 2020-11-08 21:58:02 UTC 
Alright thank you, I am also running on a Vega 8. Thanks for verifying that it is only on Wayland, will need to investigate what's going on there.
Comment 6 Fabian Vogt 2020-11-09 12:43:16 UTC 
The BusyIndicator is the main cause for excessive CPU use and slowness here. Making that invisible improves it significantly, but it's still not responsive enough. I can't narrow it down to any other specific component after that though, it seems to be spread out over the entire tree. e.g. making the the pie charts invisible helps a bit, hiding the process table helps a bit, etc.
Comment 7 Matej Mrenica 2021-01-26 12:32:35 UTC 
Does anyone still have this issue? I don't since 5.21 Beta.
Comment 8 Eric Armbruster 2021-01-26 13:35:15 UTC 
Can confirm. The issue is no longer present on Wayland (Plasma 5.21 Beta).
Comment 9 Arjen Hiemstra 2021-01-26 13:41:52 UTC 
Great. Then I'm closing this.