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<title>Comparing the performance of a sequence of several generators</title>
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<div class="titlepage"><div><div><h5 class="title">
<a name="spirit.karma.performance_measurements.numeric_performance.format_performance"></a><a class="link" href="format_performance.html" title="Comparing the performance of a sequence of several generators">Comparing
the performance of a sequence of several generators</a>
</h5></div></div></div>
<p>
These performance measurements are centered around formatting of a sequence
of different items, including 2 <code class="computeroutput"><span class="keyword">double</span></code>
floating point numbers using different libraries and methods. The overall
execution times for those examples are compared below. We compare using
<code class="computeroutput"><span class="identifier">sprintf</span></code>, C++ iostreams,
<a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>, and
<span class="emphasis"><em>Spirit.Karma</em></span>.
</p>
<p>
For the full source code of the performance test please see here: <a href="../../../../../../optimization/karma/format_performance.cpp" target="_top">format_performance.cpp</a>.
All the measurements have been done by doing <code class="computeroutput"><span class="number">1e6</span></code>
iterations for each formatting type (NUMITERATIONS is set to <code class="computeroutput"><span class="number">1e6</span></code>).
</p>
<p>
Code used to measure the performance for sprintf:
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">char</span> <span class="identifier">buffer</span><span class="special">[</span><span class="number">256</span><span class="special">];</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">NUMITERATIONS</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
<span class="identifier">sprintf</span><span class="special">(</span><span class="identifier">buffer</span><span class="special">,</span> <span class="string">"[%-14.3f%-14.3f]"</span><span class="special">,</span> <span class="number">12345.12345</span><span class="special">,</span> <span class="number">12345.12345</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
</p>
<p>
Code used to measure the performance for standard iostreams:
</p>
<p>
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span> <span class="identifier">strm</span><span class="special">;</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">NUMITERATIONS</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
<span class="identifier">strm</span><span class="special">.</span><span class="identifier">str</span><span class="special">(</span><span class="string">""</span><span class="special">);</span>
<span class="identifier">strm</span> <span class="special">&lt;&lt;</span> <span class="char">'['</span>
<span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setiosflags</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios</span><span class="special">::</span><span class="identifier">fixed</span><span class="special">)</span>
<span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">left</span>
<span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setprecision</span><span class="special">(</span><span class="number">3</span><span class="special">)</span>
<span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setw</span><span class="special">(</span><span class="number">14</span><span class="special">)</span>
<span class="special">&lt;&lt;</span> <span class="number">12345.12345</span>
<span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setw</span><span class="special">(</span><span class="number">14</span><span class="special">)</span>
<span class="special">&lt;&lt;</span> <span class="number">12345.12345</span>
<span class="special">&lt;&lt;</span> <span class="char">']'</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
</p>
<p>
Code used to measure the performance for <a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>:
</p>
<p>
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">generated</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">format</span> <span class="identifier">outformat</span><span class="special">(</span><span class="string">"[%-14.3f%-14.3f]"</span><span class="special">);</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">NUMITERATIONS</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
<span class="identifier">generated</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">str</span><span class="special">(</span><span class="identifier">outformat</span> <span class="special">%</span> <span class="number">12345.12345</span> <span class="special">%</span> <span class="number">12345.12345</span><span class="special">);</span>
</pre>
<p>
</p>
<p>
The following code shows the common definitions used by all <span class="emphasis"><em>Spirit.Karma</em></span>
performance measurements as listed below:
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">double3_policy</span> <span class="special">:</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">real_policies</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span>
<span class="special">{</span>
<span class="comment">// we want to generate up to 3 fractional digits
</span> <span class="keyword">static</span> <span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">precision</span><span class="special">(</span><span class="identifier">T</span><span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="number">3</span><span class="special">;</span> <span class="special">}</span>
<span class="special">};</span>
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">real_generator</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">,</span> <span class="identifier">double3_policy</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="special">&gt;</span>
<span class="identifier">double3_type</span><span class="special">;</span>
<span class="identifier">double3_type</span> <span class="keyword">const</span> <span class="identifier">double3</span> <span class="special">=</span> <span class="identifier">double3_type</span><span class="special">();</span>
</pre>
<p>
</p>
<p>
Code used to measure the performance for <span class="emphasis"><em>Spirit.Karma</em></span>
using a plain character buffer:
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">char</span> <span class="identifier">buffer</span><span class="special">[</span><span class="number">256</span><span class="special">];</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">NUMITERATIONS</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
<span class="keyword">char</span> <span class="special">*</span><span class="identifier">p</span> <span class="special">=</span> <span class="identifier">buffer</span><span class="special">;</span>
<span class="identifier">generate</span><span class="special">(</span><span class="identifier">p</span>
<span class="special">,</span> <span class="char">'['</span> <span class="special">&lt;&lt;</span> <span class="identifier">left_align</span><span class="special">(</span><span class="number">14</span><span class="special">)[</span><span class="identifier">double3</span><span class="special">]</span> <span class="special">&lt;&lt;</span> <span class="identifier">left_align</span><span class="special">(</span><span class="number">14</span><span class="special">)[</span><span class="identifier">double3</span><span class="special">]</span> <span class="special">&lt;&lt;</span> <span class="char">']'</span>
<span class="special">,</span> <span class="number">12345.12345</span><span class="special">,</span> <span class="number">12345.12345</span><span class="special">);</span>
<span class="special">*</span><span class="identifier">p</span> <span class="special">=</span> <span class="char">'\0'</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
</p>
<p>
The following table shows the overall performance results collected while
using different compilers. All times are in seconds measured for <code class="computeroutput"><span class="number">1e6</span></code> iterations (platform: Windows7, Intel
Core Duo(tm) Processor, 2.8GHz, 4GByte RAM). For a more readable comparison
of the results see this <a class="link" href="format_performance.html#spirit.karma.format_performance" title="Figure&#160;5.&#160;Performance comparison for a sequence of several items">figure</a>.
</p>
<div class="table">
<a name="id1114684"></a><p class="title"><b>Table&#160;7.&#160;Performance comparison for a sequence of several items (all times
in [s], `1e6` iterations)</b></p>
<div class="table-contents"><table class="table" summary="Performance comparison for a sequence of several items (all times
in [s], `1e6` iterations)">
<colgroup>
<col>
<col>
<col>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Library
</p>
</th>
<th>
<p>
gcc 4.4.0 (32 bit)
</p>
</th>
<th>
<p>
VC++ 10 (32 bit)
</p>
</th>
<th>
<p>
Intel 11.1 (32 bit)
</p>
</th>
<th>
<p>
gcc 4.4.0 (64 bit)
</p>
</th>
<th>
<p>
VC++ 10 (64 bit)
</p>
</th>
<th>
<p>
Intel 11.1 (64 bit)
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
sprintf
</p>
</td>
<td>
<p>
1.725
</p>
</td>
<td>
<p>
1.892
</p>
</td>
<td>
<p>
1.903
</p>
</td>
<td>
<p>
1.469
</p>
</td>
<td>
<p>
1.608
</p>
</td>
<td>
<p>
1.493
</p>
</td>
</tr>
<tr>
<td>
<p>
iostreams
</p>
</td>
<td>
<p>
4.827
</p>
</td>
<td>
<p>
5.287
</p>
</td>
<td>
<p>
4.444
</p>
</td>
<td>
<p>
3.112
</p>
</td>
<td>
<p>
3.319
</p>
</td>
<td>
<p>
2.877
</p>
</td>
</tr>
<tr>
<td>
<p>
<a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>
</p>
</td>
<td>
<p>
5.881
</p>
</td>
<td>
<p>
7.089
</p>
</td>
<td>
<p>
5.801
</p>
</td>
<td>
<p>
5.455
</p>
</td>
<td>
<p>
5.254
</p>
</td>
<td>
<p>
4.164
</p>
</td>
</tr>
<tr>
<td>
<p>
<span class="emphasis"><em>Spirit.Karma</em></span>
</p>
</td>
<td>
<p>
1.942
</p>
</td>
<td>
<p>
1.242
</p>
</td>
<td>
<p>
0.999
</p>
</td>
<td>
<p>
1.334
</p>
</td>
<td>
<p>
0.758
</p>
</td>
<td>
<p>
0.686
</p>
</td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><p>
</p>
<div class="figure">
<a name="spirit.karma.format_performance"></a><p class="title"><b>Figure&#160;5.&#160;Performance comparison for a sequence
of several items</b></p>
<div class="figure-contents"><span class="inlinemediaobject"><img src="../../../.././images/format_performance.png" alt="Performance comparison for a sequence of several items"></span></div>
</div>
<p><br class="figure-break">
</p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2001-2010 Joel de Guzman, Hartmut Kaiser<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
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