Bug 320210 - kwin cpu usage whilst switching between virtual desktops which have several windows open
Summary: kwin cpu usage whilst switching between virtual desktops which have several w...
Status: RESOLVED DUPLICATE of bug 313016
Alias: None
Product: kwin
Classification: Plasma
Component: general (show other bugs)
Version: 4.10.2
Platform: Fedora RPMs Linux
: NOR major
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-05-24 11:16 UTC by pauloedgarcastro
Modified: 2013-05-24 13:48 UTC (History)
0 users

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
Output of "qdbus org.kde.kwin /KWin supportInformation" (2.29 KB, text/plain)
2013-05-24 12:13 UTC, pauloedgarcastro
Details

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Description pauloedgarcastro 2013-05-24 11:16:16 UTC
Hi all.

I have many ( > 20 ) different windows open in each one of the 8 virtual desktops I have set up.

Lately, or at least since the upgrade to Fedora 17, I think I've noticed that switching between virtual desktops, specially if I'm switching to one which has many windows open, seems to be a very expensive process.
Sometimes it can take up to 5 secs until I can get something to be written in the default focus window.

It's almost like kwin is enumerating all the windows in this new desktop that it switched to ( hich makes some sense ), but doing it at a very high cpu cost.

The kwin,X processes seem to use a lot of CPU whilst the process of switching is happening.

If we couple this with some extra load coming from some other process say Firefox, or some heavy IO operation for instance, then the system becomes almost unusable from the perspective of someone who's frequently changing from virtual desktop to another.

This didn't used to be the case some months ago...

I'm on Fedora17.
kde-workspace-4.10.2-4.fc17.x86_64
kernel-3.8.8-100.fc17.x86_64


Reproducible: Always

Steps to Reproduce:
1. Login to the system, open many ( > 20 )  windows ( Konsole, emacs, okular, firefox ) in different desktops
2. Switch from one virtual Desktop to another 
3. Evaluate how long it takes to be able to write something in the default window
Actual Results:  
General slowness all across the UI

Expected Results:  
I would have expected the system to be able to cope

Whilst this slowness is happening there's no swap space being used.
Comment 1 Martin Flöser 2013-05-24 11:38:38 UTC
please provide output of:
qdbus org.kde.kwin /KWin supportInformation
Comment 2 pauloedgarcastro 2013-05-24 12:13:06 UTC
Created attachment 80055 [details]
Output of "qdbus org.kde.kwin /KWin supportInformation"

Adding the output of 
qdbus org.kde.kwin /KWin supportInformation
as requested.
Comment 3 Martin Flöser 2013-05-24 12:28:44 UTC
Please try enabling desktop effects, this should fix the problem.
Comment 4 Thomas Lübking 2013-05-24 12:33:18 UTC
Also: what decoration do you use?
(we should have that in the support info ;-)
Comment 5 Martin Flöser 2013-05-24 12:59:12 UTC
> (we should have that in the support info ;-)
it's on my TODO list, maybe I should once pick that todo
Comment 6 pauloedgarcastro 2013-05-24 13:30:59 UTC
Turning on the desktop effects does seem to improve the situation massively.
I always had those off as I associated them with extra CPU being diverted into the window manager to do all the fancy animations...
It never really occurred to me that enabling them would speed up the general user experience.

As for the decoration, if I understand correctly, I am using Plastik.

( 30 mins later ) 
So far so good, and assuming this will hold at the next reboot which I'm sure it will as far as I'm concerned this is fixed.
Many thanks.
Comment 7 Thomas Lübking 2013-05-24 13:48:39 UTC
(In reply to comment #6)

> As for the decoration, if I understand correctly, I am using Plastik.
Don't use Aurorae themes (this nowadays also includes Plastik) with the native graphicssystem or without compositing.

*** This bug has been marked as a duplicate of bug 313016 ***