Bug 498941 - High iGPU utilisation of plasmashell/kwin_wayland while panel hidden
Summary: High iGPU utilisation of plasmashell/kwin_wayland while panel hidden
Status: REOPENED
Alias: None
Product: plasmashell
Classification: Plasma
Component: Panel (show other bugs)
Version: 6.3.0
Platform: Arch Linux Linux
: NOR normal
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-01-20 22:52 UTC by Deinorius
Modified: 2025-03-03 20:40 UTC (History)
3 users (show)

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Description Deinorius 2025-01-20 22:52:00 UTC
SUMMARY
I have a ThinkPad T490 with a Core i5 8365U, which is important, as I guess, a way more powerful Desktop system won't see any substantial utilisation over the usual with a performant graphics card, as the 2018/2019 Intel iGPU is weak.
I have been getting this symptom for months irregularly (probably since Plasma 6?), but right now it's especially annoying, and I found out, how I could reproduce it better.

STEPS TO REPRODUCE
Caution: This doesn't happen all the time, only at specific times I can't be sure of.
1. System panel is set to hidden, where you can get it up with the mouse. Floating panel or not doesn't seem to matter, as this bug isn't there, when the panel is generally shown.
2. Switch between apps with Alt-Tab or to yakuake with F12 without the panel popping up.

OBSERVED RESULT
High iGPU utilisation (60-80 %) while doing nothing and opened programs. When I move the mouse to the system panel to bring it up, utilisation goes down to normal level.
If I'm correct, I could recognise this more often after a system update and cold restart (no soft reboot). After another reboot it went away, and I didn't think about it any longer, until it came back and because I'm on a laptop I can hear this.

EXPECTED RESULT
No high utilisation out of the blue.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:  Arch linux-zen 6.12.10
KDE Plasma Version: 6.2.5 @ wayland
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1

ADDITIONAL INFORMATION
Right now I couldn't reproduce this with another user account on the same laptop and OS, but I accidentally rebooted the system, so I can't say, if the reboot did help or the new user. Back to my normal account, it went away as usual.

Is there a way to check, what calls contribute to this? Is dmesg an option, of which I didn't think earlier ...
Comment 1 Nate Graham 2025-01-21 20:56:17 UTC
Do you by any chance use multiple virtual desktops?

Is it consistent that the high GPU utilization is seen only while the panel is hidden?
Comment 2 Deinorius 2025-01-21 21:55:59 UTC
Virtual Desktop is active, even though apps haven't been outside the first one.

It is consistent, that the behaviour only happens, when panel is hidden. I changed it to different options, and it was gone. I set it to hidden again and the high utilisation came back. At least at that session, after rebooting it went away.

It is inconsistent, when it happens at all. That's why I have to check, if it comes back after a system update with triggering mkinitcpio.
Comment 3 Nate Graham 2025-01-22 00:34:11 UTC
I had a feeling. It might be a variant of Bug 487895.

What's on your panel?
Comment 4 Deinorius 2025-01-22 00:50:32 UTC
I see, but in my case it's GPU utilisation in wayland.

Panel contains mostly the usual suspects: launcher button - apps - space - Application Title Bar - Arch Update Checker - system tray

I found one reason for this to happen. The panel still has to be hidden, and after I'm did some work in Google Docs in Firefox I download/save the document as PDF, Firefox opens that file and GPU utilisation stays up, until I move the cursor to the panel and bringing it up. Utilisation goes down. Virtual Desktop was deactivated this time.
Comment 5 Nate Graham 2025-01-22 22:08:58 UTC
Thanks. It definitely sounds to me like it's the same Qt issue that Bug 487895 describes, but let's be sure. Vlad, do you agree with my assessment?
Comment 6 Deinorius 2025-01-23 00:33:30 UTC
I read the other thread to the end and tried out a few things.

1. Now, my laptop is hooked to a Dockingstation via USB-C, and I'm using both displays (monitor and laptop display). I don't experience this bug with this setup. Saving a Google doc as PDF doesn't trigger it.
Panel is only on main monitor, auto-hidden, on the laptop display there is none.
2. I removed Application Title Bar and added CatWalk to the panel. Added a Virtual Desktop and switched via shortcut between those two and btop open on both desktops. No GPU utilisation above the expected at all.

I might be mistaken, but I can't seem to remember to have experienced this behaviour while being docked.
Comment 7 Bug Janitor Service 2025-02-07 03:47:06 UTC Comment hidden (spam)
Comment 8 Bug Janitor Service 2025-02-22 03:46:53 UTC Comment hidden (spam)
Comment 9 Deinorius 2025-03-03 20:40:43 UTC
Back again to report the bug is still present. Right now (after Standby) it is really aggressive.
I thought it to get triggered after some specific iGPU workload. It doesn't matter which; Firefox, firefoxpwa, Dolphin, When I changed the folder in Dolphin, iGPU started to get hot for example.

But then, I just did nothing at all. I brought up the panel to normalise iGPU, counted the seconds, and it went off again. Duration was different every time. 20 s, 30 s, 14 s ... It's awful now.

I should go away again, after updating or just rebooting, but I would prefer to keep it this way, so I can help you find the problem. Is there some way to make this visible? Nothing in dmesg gives me a hint, in my opinion.