Bug 492711

Summary:	switching virtual desktops gets kwin stuck at high CPU usage
Product:	[Plasma] kwin	Reporter:	hinsch.martin
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	nate
Priority:	NOR
Version First Reported In:	6.0.5
Target Milestone:	---
Platform:	Manjaro
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description hinsch.martin 2024-09-06 11:44:24 UTC

SUMMARY

When switching virtual desktops CPU usage of kwin_x11, Xorg and plasmashell increases to about 10%, 6% and 4%, respectively. It stays there until the taskbar is activated after which each of the percentages immediately drops down to below 0.5. 


STEPS TO REPRODUCE
1. Switch virtual desktop using a keyboard shortcut.
2. Activate panel or taskbar.

OBSERVED RESULT

Persistent high CPU usage until panel is triggered.

EXPECTED RESULT

Short spike in CPU usage while switching desktops.


SOFTWARE/OS VERSIONS
(available in the Info Center app, or by running `kinfo` in a terminal window)
KDE Plasma Version:  6.0.5
KDE Frameworks Version:  6.5.0
Qt Version:  6.7.2

ADDITIONAL INFORMATION

Comment 1 Nate Graham 2024-09-16 19:18:25 UTC

Do you have an auto-hide panel?

Does it also happen in Plasma 6.1.4 or later?

Comment 2 hinsch.martin 2024-09-16 19:27:07 UTC

(In reply to Nate Graham from comment #1)
> Do you have an auto-hide panel?

Yes.

> 
> Does it also happen in Plasma 6.1.4 or later?

I don't know, I'm on Manjaro stable, so 6.0.5 is the latest version for me.

Comment 3 Nate Graham 2024-09-17 16:49:49 UTC

Darn. That's a shame. If you make your panel always visible, does the issue go away?

Comment 4 hinsch.martin 2024-09-17 18:06:12 UTC

(In reply to Nate Graham from comment #3)
> Darn. That's a shame. If you make your panel always visible, does the issue
> go away?

It does indeed. Interestingly it also goes away if I set it to 'dodge windows', even if I switch onto a desktop with a full screen window (and thus hidden panel). Which, incidentally, solves the problem for me.

Comment 5 Nate Graham 2024-09-17 22:28:58 UTC

And I'm guessing you have your Digital Clock to show seconds, right? If so, this is Bug 487895. Even if it's not, it might be that issue anyway, and showing seconds is either unrelated, or an example of the issue caused by of having something updating on the panel while it's hidden.

Comment 6 hinsch.martin 2024-09-18 10:02:41 UTC

(In reply to Nate Graham from comment #5)
> And I'm guessing you have your Digital Clock to show seconds, right? If so,
> this is Bug 487895. Even if it's not, it might be that issue anyway, and
> showing seconds is either unrelated, or an example of the issue caused by of
> having something updating on the panel while it's hidden.

No, it's set to minutes and I don't have anything non-standard in the panel otherwise either (as far as I can tell), i.e. launcher, desktops, task manager, system tray, clock and show desktop button. But I guess task manager and desktops both will update while switching between desktops.

Comment 7 hinsch.martin 2024-09-18 10:08:07 UTC

(In reply to hinsch.martin from comment #6)
> (In reply to Nate Graham from comment #5)
> > And I'm guessing you have your Digital Clock to show seconds, right? If so,
> > this is Bug 487895. Even if it's not, it might be that issue anyway, and
> > showing seconds is either unrelated, or an example of the issue caused by of
> > having something updating on the panel while it's hidden.
> 
> No, it's set to minutes and I don't have anything non-standard in the panel
> otherwise either (as far as I can tell), i.e. launcher, desktops, task
> manager, system tray, clock and show desktop button. But I guess task
> manager and desktops both will update while switching between desktops.

But I've read Bug 487895 and it does sound as if it's the same thing.

Comment 8 Nate Graham 2024-09-18 12:19:27 UTC

Yeah, agreed. Thanks a lot!

*** This bug has been marked as a duplicate of bug 487895 ***