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List: kde-panel-devel
Subject: Review Request: Fixing massive memory consumption in KWin using the
From: "Philipp Knechtges" <philipp-dev () knechtges ! com>
Date: 2011-05-18 20:53:20
Message-ID: 20110518205320.27292.32822 () vidsolbach ! de
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This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/101385/
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Review request for kwin and Plasma.
Summary
-------
The intention of this patch is to lower the heap fragmentation in KWin when using the \
raster backend.
One can illustrate the issue with the following testcase: If one currently uses the \
raster backend and switches back to non-compositing mode one gets easily a similar \
memory usage like the following:
Situation: 14 windows, QtCurve
KWin started with compositing: 40 MB
KWin switched to non-compositing : more than 70 MB
The first guess might be, that this is due to a memleak because of not properly \
released pixmaps. But calling malloc_stats() sheds some more light on the subject \
(non-compositing mode):
Arena 0:
system bytes = 72232960
in use bytes = 8180512
Arena 1:
system bytes = 135168
in use bytes = 4784
Total (incl. mmap):
system bytes = 73080832
in use bytes = 8898000
max mmap regions = 13
max mmap bytes = 36343808
In other words, the glibc has allocated more than 70 MB memory although KWin uses \
only less than 10 MB. The problem is that glibc only resizes the heap if the heap has \
more than 128 KB of free space at the end, but many decoration pixmaps are smaller. \
Using mallopt to tune the threshold to 20 KB (i'm open for other suggestions?) fixes \
the issue. After the patch:
KWin in compositing mode: 19 MB
KWin switched to non-compositing: 13 MB
Arena 0:
system bytes = 12374016
in use bytes = 6894544
Arena 1:
system bytes = 135168
in use bytes = 4784
Total (incl. mmap):
system bytes = 13750272
in use bytes = 8140416
max mmap regions = 67
max mmap bytes = 99463168
Are there some negative effects?
The only negative effect i am aware of is, that Glibc free() is calling the sbrk \
syscall more often. But this should not be a bottleneck.
Diffs
-----
kwin/composite.cpp 9edb99d
kwin/main.cpp f767f54
Diff: http://git.reviewboard.kde.org/r/101385/diff
Testing
-------
Tested using a standard Fedora 14.
Would be nice to know, whether other OSes have similar issues?
Martin Gräßlin had some concerns about the portability?
Thanks,
Philipp
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This is an automatically generated e-mail. To reply, visit:
<a href="http://git.reviewboard.kde.org/r/101385/">http://git.reviewboard.kde.org/r/101385/</a>
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<div>Review request for kwin and Plasma.</div>
<div>By Philipp Knechtges.</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">The intention of this patch is to lower the heap fragmentation in KWin \
when using the raster backend.
One can illustrate the issue with the following testcase: If one currently uses the \
raster backend and switches back to non-compositing mode one gets easily a similar \
memory usage like the following:
Situation: 14 windows, QtCurve
KWin started with compositing: 40 MB
KWin switched to non-compositing : more than 70 MB
The first guess might be, that this is due to a memleak because of not properly \
released pixmaps. But calling malloc_stats() sheds some more light on the subject \
(non-compositing mode):
Arena 0:
system bytes = 72232960
in use bytes = 8180512
Arena 1:
system bytes = 135168
in use bytes = 4784
Total (incl. mmap):
system bytes = 73080832
in use bytes = 8898000
max mmap regions = 13
max mmap bytes = 36343808
In other words, the glibc has allocated more than 70 MB memory although KWin uses \
only less than 10 MB. The problem is that glibc only resizes the heap if the heap has \
more than 128 KB of free space at the end, but many decoration pixmaps are smaller. \
Using mallopt to tune the threshold to 20 KB (i'm open for other suggestions?) \
fixes the issue. After the patch:
KWin in compositing mode: 19 MB
KWin switched to non-compositing: 13 MB
Arena 0:
system bytes = 12374016
in use bytes = 6894544
Arena 1:
system bytes = 135168
in use bytes = 4784
Total (incl. mmap):
system bytes = 13750272
in use bytes = 8140416
max mmap regions = 67
max mmap bytes = 99463168
Are there some negative effects?
The only negative effect i am aware of is, that Glibc free() is calling the sbrk \
syscall more often. But this should not be a bottleneck.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">Tested using a standard Fedora 14. Would be nice to know, whether other \
OSes have similar issues? Martin Gräßlin had some concerns about the \
portability?</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>kwin/composite.cpp <span style="color: grey">(9edb99d)</span></li>
<li>kwin/main.cpp <span style="color: grey">(f767f54)</span></li>
</ul>
<p><a href="http://git.reviewboard.kde.org/r/101385/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
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