Bug 183680 - sudden slowdown when opening more than 10 windows
Summary: sudden slowdown when opening more than 10 windows
Status: RESOLVED FIXED
Alias: None
Product: kwin
Classification: Plasma
Component: general (show other bugs)
Version: git master
Platform: Fedora RPMs Unspecified
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
: 253903 (view as bug list)
Depends on:
Blocks:
 
Reported: 2009-02-08 13:53 UTC by Mark van Rossum
Modified: 2011-12-22 10:25 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In: 4.8.0


Attachments
kcachegrind view (355.86 KB, image/png)
2010-10-11 11:29 UTC, Jaime Torres
Details

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Description Mark van Rossum 2009-02-08 13:53:59 UTC
Version:            (using KDE 4.2.0)
Installed from:    Fedora RPMs

I use nedit as my default editor.
I notice a sudden slowdown when I open more than say 10 windows, with
commands such as "nedit *"
The first windows are drawn up quickly, the last ones take almost a second each.


Open 9 windows:
   time nedit *.cc 
1.6 sec

Open 17 windows
   time nedit *.hh *.cc
7.2 sec

Note,
1) the files opened are all small (<15k).

2) the slowdown does not seem to come from the task manager (same times without it)

3) Nedit is a motif application, I have not exhaustively tested but I do not see this slowdown with for instance gnuplot.

4) In gnome the speeds are fine.
Comment 1 Mark van Rossum 2009-03-03 15:15:34 UTC
This bug is intermittent.
I wish I could narrow it down a bit...
Comment 2 Mark van Rossum 2009-03-19 01:28:39 UTC
Seems to have disappeared in 4.2.1.
Comment 3 Mark van Rossum 2009-12-22 12:48:20 UTC
Reopening, because this bug is back in 4.3.4.

It took 39sec to open 17 windows !
Comment 4 Jaime Torres 2009-12-29 19:04:56 UTC
I think this is not a plasma issue, but a kwin issue.
The tests I've done:

kwrite 20 small files from the same machine:
kwin decoration (aurorae and keramik)
with plasma-desktop and with kwin, the last kwrite window took almost 1 second.
with plasma-desktop and with icewm, all the kwrite window took the same time.
without plasma-desktop and with kwin, the last kwrite window took almost 1 second.

nedit 20 small files from a remote idle machine (ssh -X):
kwin decoration (aurorae)
without plasma-desktop and with icewm, 42 real seconds/31 user cpu seconds to show them all.
with plasma-desktop and with icewm, 43 real seconds/31 user cpu seconds.
without plasma-desktop and with kwin, 47 real seconds/31 user cpu seconds.
with plasma-desktop and with kwin, 50 real seconds/32 user cpu seconds.
kwin decoration (keramik)
with plasma-desktop and with kwin, 43 real seconds/32 user cpu seconds.
Comment 5 Michael Leupold 2010-10-10 14:19:58 UTC
I can confirm this on trunk r1184315 using an NVIDIA GeForce 8600 GTS and the 256.35 driver. It happens regardless of desktop effects enabled or disabled.
Comment 6 Thomas Lübking 2010-10-10 21:01:40 UTC
from comment #4 it seems to be related to the decoration. 

@mark/michael:
can you confirm that it's related to the decroation?


and erhemm:
from the numbers the difference is apparently not in the user but only in the real time, thus kernel/driver related and aurorae actually uses libplasma to render the decoration ;-)
Comment 7 Michael Leupold 2010-10-10 21:51:23 UTC
After retrying I think it might actually be more related to the application painting itself as it also happens with the Modern System decoration. However with nedit I see a short delay but even after 40 files I'd say it still opens fast enough (almost unnoticeable and not the 1s delay mentioned by the reporter) - thus the main delay seems to be related to Oxygen style using up CPU instead of a bug in KWin. I tried with 41 windows.
Comment 8 Thomas Lübking 2010-10-10 22:22:31 UTC
The nvidia driver has a performance issue with it's pixmap cache (being used to allocate 32bit pixmaps) becoming flooded.
Since many oxygen windows will allocate many 32bit pixmaps the cache (might) slow(s) down notably. This would explain the overhead on the system time (any why aurorae is somehow slower than keramik)

Notice that while i can confirm this for the css nvidia driver, it does not mean that other drivers do not expose similar issues...
Comment 9 Mark van Rossum 2010-10-10 22:39:08 UTC
Sorry, I can't help any further.

I suspect it is the combination Nvidia + KDE, both have been upgraded many times since I reported this bug.

I'm now using gnome (+some kde applications) all the time, which works great.
Comment 10 Jaime Torres 2010-10-11 11:29:22 UTC
Created attachment 52410 [details]
kcachegrind view

What I see in this kcachegrind view, created only opening 94 small .h files with kwrite and then closing them all, is:

KWin::Workspace::createClient uses 9.21 %cpu, called 105 times.

I hope it is usefull.
The cachegrind is 1.1Mib after compression. more than accepted by bko.
Comment 11 Martin Flöser 2011-01-22 09:33:24 UTC
what's the state with more recent version of KDE (4.6) and more recent versions of the NVIDIA blob?
Comment 12 Martin Flöser 2011-12-22 10:25:09 UTC
With 4.8 we have significant performance improvements. The number of open windows should no longer influence the performance at all. Because of that I consider this bug report as fixed.

In case you still experience slowdown with 4.8 I would like to ask you to open a new bug report with current information as the bug is rather old.
Comment 13 Martin Flöser 2011-12-22 10:25:43 UTC
*** Bug 253903 has been marked as a duplicate of this bug. ***