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<div class="titlepage"><div><div><h5 class="title">
<a name="spirit.karma.performance_measurements.numeric_performance.int_performance"></a><a class="link" href="int_performance.html" title="Comparing the performance of a single int_ generator">
Comparing the performance of a single int_ generator</a>
</h5></div></div></div>
<p>
These performance measurements are centered around default formatting
of a single <code class="computeroutput"><span class="keyword">int</span></code> integer
number 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/int_generator.cpp" target="_top">int_generator.cpp</a>.
All the measurements have been done by executing <code class="computeroutput"><span class="number">1e7</span></code>
iterations for each formatting type (NUMITERATIONS is set to <code class="computeroutput"><span class="number">1e7</span></code> in the code shown below).
</p>
<p>
Code used to measure the performance for <code class="computeroutput"><span class="identifier">ltoa</span></code>:
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">char</span> <span class="identifier">buffer</span><span class="special">[</span><span class="number">65</span><span class="special">];</span> <span class="comment">// we don't expect more than 64 bytes to be generated here
</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"><</span> <span class="identifier">MAX_ITERATION</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">ltoa</span><span class="special">(</span><span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">],</span> <span class="identifier">buffer</span><span class="special">,</span> <span class="number">10</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
</p>
<p>
Code used to measure the performance for standard C++ iostreams:
</p>
<p>
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span> <span class="identifier">str</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"><</span> <span class="identifier">MAX_ITERATION</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">str</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">str</span> <span class="special"><<</span> <span class="identifier">v</span><span class="special">[</span><span class="identifier">i</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">str</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">format</span> <span class="identifier">int_format</span><span class="special">(</span><span class="string">"%d"</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"><</span> <span class="identifier">MAX_ITERATION</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">str</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">int_format</span> <span class="special">%</span> <span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">]);</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">65</span><span class="special">];</span> <span class="comment">// we don't expect more than 64 bytes to be generated here
</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"><</span> <span class="identifier">MAX_ITERATION</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">ptr</span> <span class="special">=</span> <span class="identifier">buffer</span><span class="special">;</span>
<span class="identifier">karma</span><span class="special">::</span><span class="identifier">generate</span><span class="special">(</span><span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">int_</span><span class="special">,</span> <span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">]);</span>
<span class="special">*</span><span class="identifier">ptr</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">1e7</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="int_performance.html#spirit.karma.int_performance" title="Figure 3. Performance comparison for a single int">figure</a>.
</p>
<div class="table">
<a name="id1154500"></a><p class="title"><b>Table 5. Performance comparison for a single int (all times in [s], `1e7`
iterations)</b></p>
<div class="table-contents"><table class="table" summary="Performance comparison for a single int (all times in [s], `1e7`
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>
ltoa
</p>
</td>
<td>
<p>
1.542
</p>
</td>
<td>
<p>
0.895
</p>
</td>
<td>
<p>
0.884
</p>
</td>
<td>
<p>
1.163
</p>
</td>
<td>
<p>
1.099
</p>
</td>
<td>
<p>
0.906
</p>
</td>
</tr>
<tr>
<td>
<p>
iostreams
</p>
</td>
<td>
<p>
6.548
</p>
</td>
<td>
<p>
13.727
</p>
</td>
<td>
<p>
11.898
</p>
</td>
<td>
<p>
3.464
</p>
</td>
<td>
<p>
8.316
</p>
</td>
<td>
<p>
8.115
</p>
</td>
</tr>
<tr>
<td>
<p>
<a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>
</p>
</td>
<td>
<p>
16.998
</p>
</td>
<td>
<p>
21.813
</p>
</td>
<td>
<p>
20.477
</p>
</td>
<td>
<p>
17.464
</p>
</td>
<td>
<p>
14.662
</p>
</td>
<td>
<p>
13.646
</p>
</td>
</tr>
<tr>
<td>
<p>
<span class="emphasis"><em>Spirit.Karma</em></span> int_
</p>
</td>
<td>
<p>
1.421
</p>
</td>
<td>
<p>
0.744
</p>
</td>
<td>
<p>
0.697
</p>
</td>
<td>
<p>
1.072
</p>
</td>
<td>
<p>
0.953
</p>
</td>
<td>
<p>
0.606
</p>
</td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><p>
</p>
<div class="figure">
<a name="spirit.karma.int_performance"></a><p class="title"><b>Figure 3. Performance comparison for a single int</b></p>
<div class="figure-contents"><span class="inlinemediaobject"><img src="../../../.././images/int_performance.png" alt="Performance comparison for a single int"></span></div>
</div>
<p><br class="figure-break">
</p>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 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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