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  1. <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>DHCP Performance Guide</title><link rel="stylesheet" type="text/css" href="bind10-guide.css"><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"><meta name="description" content="BIND 10 is a framework that features Domain Name System (DNS) suite and Dynamic Host Configuration Protocol (DHCP) servers with development managed by Internet Systems Consortium (ISC). This document describes various aspects of DHCP performance, measurements and tuning. It covers BIND 10 DHCP (codename Kea), existing ISC DHCP4 software, perfdhcp (a DHCP performance measurement tool) and other related topics."></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" title="DHCP Performance Guide"><div class="titlepage"><div><div><h1 class="title"><a name="idp61888"></a>DHCP Performance Guide</h1></div><div><div class="author"><h3 class="author"><span class="firstname">Tomasz</span> <span class="surname">Mrugalski</span></h3></div></div><div><p class="releaseinfo">This is a companion document for BIND 10 version
    2. 

  2.     20120405.</p></div><div><p class="copyright">Copyright © 2012 Internet Systems Consortium, Inc. ("ISC")</p></div><div><div class="abstract" title="Abstract"><p class="title"><b>Abstract</b></p><p>BIND 10 is a framework that features Domain Name System
    3. 

  3.       (DNS) suite and Dynamic Host Configuration Protocol (DHCP)
    4. 

  4.       servers with development managed by Internet Systems Consortium (ISC).
    5. 

  5.       This document describes various aspects of DHCP performance,
    6. 

  6.       measurements and tuning. It covers BIND 10 DHCP (codename Kea),
    7. 

  7.       existing ISC DHCP4 software, perfdhcp (a DHCP performance
    8. 

  8.       measurement tool) and other related topics.</p></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="preface"><a href="#idp68352">Preface</a></span></dt><dd><dl><dt><span class="section"><a href="#acknowledgements">1. Acknowledgements</a></span></dt></dl></dd><dt><span class="chapter"><a href="#intro">1. Introduction</a></span></dt><dt><span class="chapter"><a href="#dhcp4">2. ISC DHCP 4.x</a></span></dt><dt><span class="chapter"><a href="#kea">3. Kea</a></span></dt><dd><dl><dt><span class="section"><a href="#idp76720">3.1. Backend performance evaluation</a></span></dt><dt><span class="section"><a href="#mysql-backend">3.2. MySQL backend</a></span></dt><dd><dl><dt><span class="section"><a href="#idp100032">3.2.1. MySQL tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#sqlite-ubench">3.3. SQLite-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#sqlite-tweaks">3.3.1. SQLite tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#memfile-ubench">3.4. memfile-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#memfile-tweaks">3.4.1. memfile tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#idp121008">3.5. Performance measurements</a></span></dt></dl></dd><dt><span class="chapter"><a href="#perfdhcp">4. perfdhcp</a></span></dt></dl></div><div class="list-of-tables"><p><b>List of Tables</b></p><dl><dt>3.1. <a href="#idp124112">Synchronous results:</a></dt><dt>3.2. <a href="#idp144992">Asynchronous results:</a></dt><dt>3.3. <a href="#idp165040">Estimated performance</a></dt></dl></div><div class="preface" title="Preface"><div class="titlepage"><div><div><h2 class="title"><a name="idp68352"></a>Preface</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#acknowledgements">1. Acknowledgements</a></span></dt></dl></div><div class="section" title="1. Acknowledgements"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="acknowledgements"></a>1. Acknowledgements</h2></div></div></div><p>ISC would like to acknowledge generous support for
    9. 

  9.       BIND 10 development of DHCPv4 and DHCPv6 components provided
    10. 

  10.       by <a class="ulink" href="http://www.comcast.com/" target="_top">Comcast</a>.</p></div></div><div class="chapter" title="Chapter 1. Introduction"><div class="titlepage"><div><div><h2 class="title"><a name="intro"></a>Chapter 1. Introduction</h2></div></div></div><p>
    11. 

  11.       This document is in its early stages of development. It is
    12. 

  12.       expected to grow significantly in a near future. It will
    13. 

  13.       cover topics like database backend perfomance measurements,
    14. 

  14.       pros an cons of various optimization techniques and
    15. 

  15.       tools.
    16. 

  16.     </p></div><div class="chapter" title="Chapter 2. ISC DHCP 4.x"><div class="titlepage"><div><div><h2 class="title"><a name="dhcp4"></a>Chapter 2. ISC DHCP 4.x</h2></div></div></div><p>
    17. 

  17.       TODO: Write something about ISC DHCP4 here.
    18. 

  18.     </p></div><div class="chapter" title="Chapter 3. Kea"><div class="titlepage"><div><div><h2 class="title"><a name="kea"></a>Chapter 3. Kea</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#idp76720">3.1. Backend performance evaluation</a></span></dt><dt><span class="section"><a href="#mysql-backend">3.2. MySQL backend</a></span></dt><dd><dl><dt><span class="section"><a href="#idp100032">3.2.1. MySQL tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#sqlite-ubench">3.3. SQLite-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#sqlite-tweaks">3.3.1. SQLite tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#memfile-ubench">3.4. memfile-ubench</a></span></dt><dd><dl><dt><span class="section"><a href="#memfile-tweaks">3.4.1. memfile tweaks</a></span></dt></dl></dd><dt><span class="section"><a href="#idp121008">3.5. Performance measurements</a></span></dt></dl></div><p>
    19. 

  19. 

  20.     </p><div class="section" title="3.1. Backend performance evaluation"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp76720"></a>3.1. Backend performance evaluation</h2></div></div></div><p>
    21. 

  21.         Kea will support several different database backends, using
    22. 

  22.         both popular databases (like MySQL or SQLite) and
    23. 

  23.         custom-developed solutions (like in-memory database).  BIND 10
    24. 

  24.         source code features set of performance microbenchmarks.
    25. 

  25.         These are small tools written in C/C++ that simulate expected
    26. 

  26.         DHCP server behaviour and evaluate the performance of
    27. 

  27.         considered databases. As implemented benchmarks are not really
    28. 

  28.         simulating DHCP operation, but rather use set of primitives
    29. 

  29.         that can be used by a real server, they are called
    30. 

  30.         micro-benchmarks.
    31. 

  31.       </p><p>Although there are many operations and data types that
    32. 

  32.       server could store in a database, the most frequently used data
    33. 

  33.       type is lease information. Although lease information for IPv4
    34. 

  34.       and IPv6 differs slightly, it is expected that the performance
    35. 

  35.       differences will be minimal between IPv4 and IPv6 lease operations.
    36. 

  36.       Therefore each test uses lease4 table for performance measurements.
    37. 

  37.       </p><p>
    38. 

  38.         Those benchmarks are stored in tests/tools/dhcp-ubench
    39. 

  39.         directory. This directory contains simplified prototypes for
    40. 

  40.         various DB back-ends that are planned or considered as a
    41. 

  41.         backend engine for BIND10 DHCP.  Athough trivial now, they are
    42. 

  42.         expected to evolve into useful tools that will allow users to
    43. 

  43.         measure performance in their specific environment.
    44. 

  44.       </p><p>
    45. 

  45.       Currently the following benchmarks are implemented:
    46. 

  46.       </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>in memory+flat file</p></li><li class="listitem"><p>SQLite</p></li><li class="listitem"><p>MySQL</p></li></ul></div><p>
    47. 

  47.     </p><p>
    48. 

  48.       As they require additional (sometimes heavy) dependencies, they are not
    49. 

  49.       built by default. Actually, their build system is completely separated.
    50. 

  50.       It will be eventually merged with the main BIND10 makefile system, but
    51. 

  51.       that is a low priority for now.
    52. 

  52.     </p><p>
    53. 

  53.       All benchmarks will follow the same pattern:
    54. 

  54.       </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>prepare operation (connect to a database, create a file etc.)</p></li><li class="listitem"><p>Measure timestamp 0</p></li><li class="listitem"><p>Commit new lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 1</p></li><li class="listitem"><p>Search for random lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 2</p></li><li class="listitem"><p>Update existing lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 3</p></li><li class="listitem"><p>Delete existing lease4 (repeated X times)</p></li><li class="listitem"><p>Measure timestamp 4</p></li><li class="listitem"><p>Print out statistics, based on X and measured timestamps.</p></li></ol></div><p>
    55. 

  55. 

  56.       Although this approach does not attempt to simulate actual DHCP server
    57. 

  57.       operation that has mix of all steps intervening, it answers the
    58. 

  58.       questions about basic database strenghts and weak points. In particular
    59. 

  59.       it can show what is the impact of specific DB optimizations, like
    60. 

  60.       changing engine, optimizing for writes/reads etc.
    61. 

  61.     </p><p>
    62. 

  62.       The framework attempts to do the same amount of operations for every
    63. 

  63.       backend thus allowing fair complarison between them.
    64. 

  64.     </p></div><div class="section" title="3.2. MySQL backend"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="mysql-backend"></a>3.2. MySQL backend</h2></div></div></div><p>MySQL backend requires MySQL client development libraries. It uses
    65. 

  65.       mysql_config tool (that works similar to pkg-config) to discover required
    66. 

  66.       compilation and linking options. To install required packages on Ubuntu,
    67. 

  67.       use the following command:
    68. 

  68. 

  69.       </p><pre class="screen">$ <strong class="userinput"><code>sudo apt-get install mysql-client mysql-server libmysqlclient-dev</code></strong></pre><p>
    70. 

  70. 

  71.       Make sure that MySQL server is running. Make sure that you have your setup
    72. 

  72.       configured so there is a user that is able to modify used database.</p><p>Before running tests, you need to initialize your database. You can
    73. 

  73.       use mysql.schema script for that purpose. WARNING: It will drop existing
    74. 

  74.       Kea database. Do not run this on your production server. Assuming your
    75. 

  75.       MySQL user is kea, you can initialize your test database by:
    76. 

  76. 

  77.       </p><pre class="screen">$ <strong class="userinput"><code>mysql -u kea -p &lt; mysql.schema</code></strong></pre><p>
    78. 

  78.       </p><p>After database is initialized, you are ready to run the test:
    79. 

  79.       </p><pre class="screen">$ <strong class="userinput"><code>./mysql_ubench</code></strong></pre><p>
    80. 

  80. 

  81.       or
    82. 

  82. 

  83.       </p><pre class="screen">$ <strong class="userinput"><code>./mysql_ubench &gt; results-&gt;mysql.txt</code></strong></pre><p>
    84. 

  84. 

  85.       Redirecting output to a file is important, because for each operation
    86. 

  86.       there is a single character printed to show progress. If you have a slow
    87. 

  87.       terminal, this may considerably affect test perfromance. On the other hand,
    88. 

  88.       printing something after each operation is required, as poor DB setting
    89. 

  89.       may slow down operations to around 20 per second. Observant user is expected
    90. 

  90.       to note that initial dots are printed too slowly and abort the test.</p><p>Currently all default parameters are hardcoded. Default values can be
    91. 

  91.       overwritten using command line switches. Although all benchmarks take
    92. 

  92.       the same list of parameters, some of them are specific to a given backend
    93. 

  93.       type. To get a list of supported parameters, run your benchmark with -h option:
    94. 

  94. 

  95.       </p><pre class="screen">$ <strong class="userinput"><code>./mysql_ubench -h</code></strong>
    96. 

  96. This is a benchmark designed to measure expected performance
    97. 

  97. of several backends. This particular version identifies itself
    98. 

  98. as following:
    99. 

  99. MySQL client version is 5.5.24
    100. 

  100. 

  101. Possible command-line parameters:
    102. 

  102.  -h - help (you are reading this)
    103. 

  103.  -m hostname - specifies MySQL server to connect (MySQL backend only)
    104. 

  104.  -u username - specifies MySQL user name (MySQL backend only)
    105. 

  105.  -p password - specifies MySQL passwod (MySQL backend only)
    106. 

  106.  -f name - database or filename (MySQL, SQLite and memfile)
    107. 

  107.  -n integer - number of test repetitions (MySQL, SQLite and memfile)
    108. 

  108.  -s yes|no - synchronous/asynchronous operation (MySQL, SQLite and memfile)
    109. 

  109.  -v yes|no - verbose mode (MySQL, SQLite and memfile)
    110. 

  110. </pre><p>
    111. 

  111. 

  112.       </p><div class="section" title="3.2.1. MySQL tweaks"><div class="titlepage"><div><div><h3 class="title"><a name="idp100032"></a>3.2.1. MySQL tweaks</h3></div></div></div><p>One parameter that has huge impact on performance is a a backend engine.
    113. 

  113.         You can get a list of engines of your MySQL implementation by using
    114. 

  114. 

  115.         </p><pre class="screen">&gt; <strong class="userinput"><code>show engines;</code></strong></pre><p>
    116. 

  116. 

  117.         in your mysql client. Two notable engines are MyISAM and InnoDB. mysql_ubench will
    118. 

  118.         use MyISAM for synchronous mode and InnoDB for asynchronous.</p></div></div><div class="section" title="3.3. SQLite-ubench"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sqlite-ubench"></a>3.3. SQLite-ubench</h2></div></div></div><p>SQLite backend requires both sqlite3 development and run-time package. Their
    119. 

  119.       names may vary from system to system, but on Ubuntu 12.04 they are called
    120. 

  120.       sqlite3 libsqlite3-dev. To install them, use the following command:
    121. 

  121. 

  122.       </p><pre class="screen">&gt; <strong class="userinput"><code>sudo apt-get install sqlite3 libsqlite3-dev</code></strong></pre><p>
    123. 

  123. 

  124.       Before running the test the database has to be created. Use the following command for that:
    125. 

  125.       </p><pre class="screen">&gt; <strong class="userinput"><code>cat sqlite.schema | sqlite3 sqlite.db</code></strong></pre><p>
    126. 

  126. 

  127.       A new database called sqlite.db will be created. That is the default name used
    128. 

  128.       by sqlite_ubench test. If you prefer other name, make sure you update
    129. 

  129.       sqlite_ubench.cc accordingly.</p><p>Once the database is created, you can run tests:
    130. 

  130.       </p><pre class="screen">&gt; <strong class="userinput"><code>./sqlite_ubench</code></strong></pre><p>
    131. 

  131.       or
    132. 

  132.       </p><pre class="screen">&gt; <strong class="userinput"><code>./sqlite_ubench &gt; results-sqlite.txt</code></strong></pre><p>
    133. 

  133.       </p><div class="section" title="3.3.1. SQLite tweaks"><div class="titlepage"><div><div><h3 class="title"><a name="sqlite-tweaks"></a>3.3.1. SQLite tweaks</h3></div></div></div><p>To modify default sqlite_ubench parameters, command line
    134. 

  134.         switches can be used. Currently supported parameters are
    135. 

  135.         (default values specified in brackets):
    136. 

  136.         </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>-f filename - name of the database file ("sqlite.db")</p></li><li class="listitem"><p>-n num - number of iterations (100)</p></li><li class="listitem"><p>-s yes|no - should the operations be performend in synchronous (yes)
    137. 

  137.           or asynchronous (no) manner (yes)</p></li><li class="listitem"><p>-v yes|no - verbose mode. Should the test print out progress? (yes)</p></li></ol></div><p>
    138. 

  138.         </p><p>SQLite can run in asynchronous or synchronous mode. This
    139. 

  139.         mode can be controlled by using sync parameter. It is set
    140. 

  140.         using (PRAGMA synchronous = ON or OFF).</p><p>Another tweakable feature is journal mode. It can be
    141. 

  141.         turned to several modes of operation. Its value can be
    142. 

  142.         modified in SQLite_uBenchmark::connect().  See
    143. 

  143.         http://www.sqlite.org/pragma.html#pragma_journal_mode for
    144. 

  144.         detailed explanantion.</p></div></div><div class="section" title="3.4. memfile-ubench"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="memfile-ubench"></a>3.4. memfile-ubench</h2></div></div></div><p>Memfile backend is custom developed prototype backend that
    145. 

  145.       somewhat mimics operation of ISC DHCP4. It uses in-memory
    146. 

  146.       storage using standard C++ and boost mechanisms (std::map and
    147. 

  147.       boost::shared_ptr&lt;&gt;). All database changes are also
    148. 

  148.       written to a lease file. That file is strictly write-only. This
    149. 

  149.       approach takes advantage of the fact that simple append is faster
    150. 

  150.       than edition with potential whole file relocation.</p><div class="section" title="3.4.1. memfile tweaks"><div class="titlepage"><div><div><h3 class="title"><a name="memfile-tweaks"></a>3.4.1. memfile tweaks</h3></div></div></div><p>To modify default memfile_ubench parameters, command line
    151. 

  151.         switches can be used. Currently supported parameters are
    152. 

  152.         (default values specified in brackets):
    153. 

  153.         </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>-f filename - name of the database file ("dhcpd.leases")</p></li><li class="listitem"><p>-n num - number of iterations (100)</p></li><li class="listitem"><p>-s yes|no - should the operations be performend in synchronous (yes)
    154. 

  154.           or asynchronous (no) manner (yes)</p></li><li class="listitem"><p>-v yes|no - verbose mode. Should the test print out progress? (yes)</p></li></ol></div><p>
    155. 

  155.         </p><p>memfile can run in asynchronous or synchronous mode. This
    156. 

  156.         mode can be controlled by using sync parameter. It uses
    157. 

  157.         fflush() and fsync() in synchronous mode to make sure that
    158. 

  158.         data is not buffered and physically stored on disk.</p></div></div><div class="section" title="3.5. Performance measurements"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp121008"></a>3.5. Performance measurements</h2></div></div></div><p>This section contains sample results for backend performance measurements,
    159. 

  159.       taken using microbenchmarks. Tests were conducted on reasonably powerful machine:
    160. 

  160.       </p><pre class="screen">
    161. 

  161. CPU: Quad-core Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz (8 logical cores)
    162. 

  162. HDD: 1,5TB Seagate Barracuda ST31500341AS 7200rpm (used only one of them), ext4 partition
    163. 

  163. OS: Ubuntu 12.04, running kernel 3.2.0-26-generic SMP x86_64
    164. 

  164. compiler: g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
    165. 

  165. MySQL version: 5.5.24
    166. 

  166. SQLite version: 3.7.9sourceid version is 2011-11-01 00:52:41 c7c6050ef060877ebe77b41d959e9df13f8c9b5e</pre><p>
    167. 

  167.       </p><p>Benchmarks were run in two series: synchronous and
    168. 

  168.       asynchronous. As those modes offer radically different
    169. 

  169.       performances, synchronous mode was conducted for 1000 (one
    170. 

  170.       thousand) repetitions and asynchronous mode was conducted for
    171. 

  171.       100000 (hundred thousand) repetitions.</p><div class="table"><a name="idp124112"></a><p class="title"><b>Table 3.1. Synchronous results:</b></p><div class="table-contents"><table summary="Synchronous results:" border="1"><colgroup><col align="center" class="Backend"><col align="center" class="Num"><col align="center" class="Create"><col align="center" class="Search"><col align="center" class="Update"><col align="center" class="Delete"></colgroup><thead><tr><th align="center">Backend</th><th align="center">Operations</th><th align="center">Create</th><th align="center">Search</th><th align="center">Update</th><th align="center">Delete</th><th align="center">Average</th></tr></thead><tbody><tr><td align="center">MySQL</td><td align="center">1000</td><td align="center">31.603978s</td><td align="center"> 0.116612s</td><td align="center">27.964191s</td><td align="center">27.695209s</td><td align="center">21.844998s</td></tr><tr><td align="center">SQLite</td><td align="center">1000</td><td align="center">61.421356s</td><td align="center"> 0.033283s</td><td align="center">59.476638s</td><td align="center">56.034150s</td><td align="center">44.241357s</td></tr><tr><td align="center">memfile</td><td align="center">1000</td><td align="center">41.711886s</td><td align="center"> 0.000724s</td><td align="center">42.267578s</td><td align="center">42.169679s</td><td align="center">31.537467s</td></tr></tbody></table></div></div><br class="table-break"><p>Following parameters were measured for asynchronous mode.
    172. 

  172.       MySQL and SQLite were run with 100 thousand repetitions. Memfile
    173. 

  173.       was run for 1 million repetitions due to much larger performance.</p><div class="table"><a name="idp144992"></a><p class="title"><b>Table 3.2. Asynchronous results:</b></p><div class="table-contents"><table summary="Asynchronous results:" border="1"><colgroup><col align="center" class="Backend"><col align="center" class="Num"><col align="center" class="Create"><col align="center" class="Search"><col align="center" class="Update"><col align="center" class="Delete"></colgroup><thead><tr><th align="center">Backend</th><th align="center">Operations</th><th align="center">Create [s]</th><th align="center">Search [s]</th><th align="center">Update [s]</th><th align="center">Delete [s]</th><th align="center">Average [s]</th></tr></thead><tbody><tr><td align="center">MySQL</td><td align="center">100000</td><td align="center">10.584842s</td><td align="center">10.386402s</td><td align="center">10.062384s</td><td align="center"> 8.890197s</td><td align="center"> 9.980956s</td></tr><tr><td align="center">SQLite</td><td align="center">100000</td><td align="center"> 3.710356s</td><td align="center"> 3.159129s</td><td align="center"> 2.865354s</td><td align="center"> 2.439406s</td><td align="center"> 3.043561s</td></tr><tr><td align="center">memfile</td><td align="center">1000000 (sic!)</td><td align="center"> 6.084131s</td><td align="center"> 0.862667s</td><td align="center"> 6.018585s</td><td align="center"> 5.146704s</td><td align="center"> 4.528022s</td></tr></tbody></table></div></div><br class="table-break"><p>Estimated performance:</p><div class="table"><a name="idp165040"></a><p class="title"><b>Table 3.3. Estimated performance</b></p><div class="table-contents"><table summary="Estimated performance" border="1"><colgroup><col align="center" class="Backend"><col align="center" class="Create"><col align="center" class="Search"><col align="center" class="Update"><col align="center" class="Delete"><col align="center" class="Average"></colgroup><thead><tr><th align="center">Backend</th><th align="center">Create [oper/s]</th><th align="center">Search [oper/s]</th><th align="center">Update [oper/s]</th><th align="center">Delete [oper/s]</th><th align="center">Average [oper/s]</th></tr></thead><tbody><tr><td align="center">MySQL (async)</td><td align="center">9447.47</td><td align="center">9627.97</td><td align="center">9938.00</td><td align="center">11248.34</td><td align="center">10065.45</td></tr><tr><td align="center">SQLite (async)</td><td align="center">26951.59</td><td align="center">31654.29</td><td align="center">34899.70</td><td align="center">40993.59</td><td align="center">33624.79</td></tr><tr><td align="center">memfile (async)</td><td align="center">164362.01</td><td align="center">1159195.84</td><td align="center">166152.01</td><td align="center">194299.11</td><td align="center">421002.24</td></tr><tr><td align="center">MySQL (sync)</td><td align="center">31.64</td><td align="center">8575.45</td><td align="center">35.76</td><td align="center">36.11</td><td align="center">2169.74</td></tr><tr><td align="center">SQLite (sync)</td><td align="center">16.28</td><td align="center">20045.37</td><td align="center">16.81</td><td align="center">17.85</td><td align="center">7524.08</td></tr><tr><td align="center">memfile (sync)</td><td align="center">23.97</td><td align="center">1381215.47</td><td align="center">23.66</td><td align="center">23.71</td><td align="center">345321.70</td></tr></tbody></table></div></div><br class="table-break"></div></div><div class="chapter" title="Chapter 4. perfdhcp"><div class="titlepage"><div><div><h2 class="title"><a name="perfdhcp"></a>Chapter 4. perfdhcp</h2></div></div></div><p>
    174. 

  174.       TODO: Write something about perfdhcp here.
    175. 

  175.     </p></div></div></body></html>
    176.