Development/Tutorials/Debugging/Shared Memory Usage in KDE - Revision history

Rakuco: /* Example program */ Add some syntax highlighting

2011-11-05T02:01:21Z

‎Example program: Add some syntax highlighting

Tstaerk: /* find out its symbols */

2011-10-16T10:01:26Z

‎find out its symbols

Tstaerk: /* disassemble it */

2011-10-16T09:58:07Z

‎disassemble it

Tstaerk at 09:57, 16 October 2011

2011-10-16T09:57:05Z

Tstaerk at 09:56, 16 October 2011

2011-10-16T09:56:38Z

Tstaerk at 09:38, 16 October 2011

2011-10-16T09:38:26Z

Tstaerk at 08:55, 16 October 2011

2011-10-16T08:55:59Z

Tstaerk: don't be negative... "most people don't understand UNIX memory management" - why do you say this?

2011-10-16T08:41:43Z

don't be negative... "most people don't understand UNIX memory management" - why do you say this?

Tstaerk at 08:38, 16 October 2011

2011-10-16T08:38:54Z

Icwiener: Fix syntax highlighting.

2011-06-27T15:37:50Z

Fix syntax highlighting.

@@ Line 61: / Line 61: @@
 </syntaxhighlight>
 '''CMakeLists.txt'''
-<pre>
+<syntaxhighlight lang="cmake">
 project (tutorial1)
 find_package(KDE4 REQUIRED)
@@ Line 70: / Line 70: @@
 target_link_libraries(tutorial1 ${KDE4_KDEUI_LIBS})
 install(TARGETS tutorial1  ${INSTALL_TARGETS_DEFAULT_ARGS})
-</pre>
+</syntaxhighlight>
 Compile and link this program:
-<pre>
 cmake . && make -j4
-</pre>
+</syntaxhighlight>
 Run it:
-<pre>
+<syntaxhighlight lang="bash">
 ./tutorial1 &
 [3] 22733
-</pre>
+</syntaxhighlight>
 In this case the program gets the process ID 22733. We look at its memory consumption:
 <pre>

@@ Line 201: / Line 201: @@
 00000000004005b4 T main
 </pre>
 = See also =
 * http://www-archive.mozilla.org/projects/footprint/footprint-guide.html

@@ Line 160: / Line 160: @@
   [...]
 You see this is the main function in real [http://www.staerk.de/thorsten/Tutorials/Assembler_Tutorial assembler code].
 = See also =
 * http://www-archive.mozilla.org/projects/footprint/footprint-guide.html

@@ Line 1: / Line 1: @@
 This article helps understanding UNIX memory management. In UNIX a process uses basically three kinds of memory segments: '''shared memory segments''', '''code segments''' and '''data segments'''.
 '''Shared memory''' is used by shared libraries. This memory is shared
 by all processes which use a certain library. Unfortunately there is no

@@ Line 130: / Line 130: @@
   VmLib:      2912 kB
 You see - not using libraries save place in memory, but as libraries are shared, it does not make sense to deny using libraries that are in memory anyway.
 = See also =
 * http://www-archive.mozilla.org/projects/footprint/footprint-guide.html

@@ Line 34: / Line 34: @@
   cat /proc/<pid-of-process>/status.
-== Example program ==
+= Example program =
 To demonstrate this, let's write a memory leaking program:
@@ Line 97: / Line 97: @@
 </pre>
 So we see the heap is counted to <tt>VmData</tt> and contained in <tt>VmRSS</tt>.
 = See also =
 * http://www-archive.mozilla.org/projects/footprint/footprint-guide.html

← Older revision		Revision as of 08:55, 16 October 2011
Line 97:		Line 97:
	</pre>		</pre>
	So we see the heap is counted to <tt>VmData</tt> and contained in <tt>VmRSS</tt>.		So we see the heap is counted to <tt>VmData</tt> and contained in <tt>VmRSS</tt>.
		+
		+	= See also =
		+	* http://www-archive.mozilla.org/projects/footprint/footprint-guide.html

← Older revision		Revision as of 08:41, 16 October 2011
Line 1:		Line 1:
−	~~It is unfortunate that a lot of people don't understand the~~ UNIX memory ~~model. Unfortunately this is helped by tools like ps which are not able to provide accurate information about memory usage~~. In UNIX a process uses basically three kinds of memory segments: '''shared memory segments''', '''code segments''' and '''data segments'''.	+	This article helps understanding UNIX memory management. In UNIX a process uses basically three kinds of memory segments: '''shared memory segments''', '''code segments''' and '''data segments'''.

	'''Shared memory''' is used by shared libraries. This memory is shared		'''Shared memory''' is used by shared libraries. This memory is shared

@@ Line 38: / Line 38: @@
 '''main.cpp'''
-<code cppqt>
+<syntaxhighlight lang="cpp-qt">
 #include <KAboutData>
 #include <KApplication>
@@ Line 58: / Line 58: @@
      return 0;
+}
-</code>
+</syntaxhighlight>
 '''CMakeLists.txt'''
-<code>
+<pre>
 project (tutorial1)
 find_package(KDE4 REQUIRED)
@@ Line 69: / Line 69: @@
 target_link_libraries(tutorial1 ${KDE4_KDEUI_LIBS})
 install(TARGETS tutorial1  ${INSTALL_TARGETS_DEFAULT_ARGS})
-</code>
+</pre>
 Compile and linkthis program:
- cmake . && make -j4
+<pre>
 Run it:
- ./tutorial1 &
+<pre>
- [3] 22733
+./tutorial1 &
 In this case the program gets the process ID 22733. We look at its memory consumption:
- cat /proc/22733/status
+<pre>
- VmRSS:     19772 kB
+cat /proc/22733/status
- VmData:     5776 kB
+VmRSS:     19772 kB
- VmStk:        84 kB
+VmData:     5776 kB
- VmExe:         8 kB
+VmStk:        84 kB
- VmLib:     26804 kB
+VmExe:         8 kB
 If we change the "100000" in the program code to "1", we get a different picture:
- VmRSS:     16624 kB
+<pre>
- VmData:     2652 kB
+VmRSS:     16624 kB
- VmStk:        84 kB
+VmData:     2652 kB
- VmExe:         8 kB
+VmStk:        84 kB
- VmLib:     26804 kB
+VmExe:         8 kB
-So we see the heap is counted to "VmData" and contained in VmRSS.
+VmLib:     26804 kB
 == Further Information ==
 More information about this topic can be found in the article about [http://ktown.kde.org/~seli/memory/analysis.html memory usage analysis].