File: //usr/share/doc/python-docs-2.4.3/html/lib/node451.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python Documentation Index' />
<link rel="first" href="lib.html" title='Python Library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="profile-instant.html" />
<link rel="prev" href="node450.html" />
<link rel="parent" href="profile.html" />
<link rel="next" href="profile-instant.html" />
<meta name='aesop' content='information' />
<title>10.2 How Is This Profiler Different From The Old Profiler?</title>
</head>
<body>
<DIV CLASS="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="10.1 Introduction to the"
href="node450.html"><img src='../icons/previous.png'
border='0' height='32' alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="10. The Python Profiler"
href="profile.html"><img src='../icons/up.png'
border='0' height='32' alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="10.3 Instant Users Manual"
href="profile-instant.html"><img src='../icons/next.png'
border='0' height='32' alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
href="contents.html"><img src='../icons/contents.png'
border='0' height='32' alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
border='0' height='32' alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
href="genindex.html"><img src='../icons/index.png'
border='0' height='32' alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="node450.html">10.1 Introduction to the</A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="profile.html">10. The Python Profiler</A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="profile-instant.html">10.3 Instant Users Manual</A>
</div>
<hr /></div>
</DIV>
<!--End of Navigation Panel-->
<H1><A NAME="SECTION0012200000000000000000">
10.2 How Is This Profiler Different From The Old Profiler?</A>
</H1>
<A NAME="Profiler_Changes"></A>
<P>
(This section is of historical importance only; the old profiler
discussed here was last seen in Python 1.1.)
<P>
The big changes from old profiling module are that you get more
information, and you pay less CPU time. It's not a trade-off, it's a
trade-up.
<P>
To be specific:
<P>
<DL>
<DT><STRONG>Bugs removed:</STRONG></DT>
<DD>Local stack frame is no longer molested, execution time is now charged
to correct functions.
<P>
</DD>
<DT><STRONG>Accuracy increased:</STRONG></DT>
<DD>Profiler execution time is no longer charged to user's code,
calibration for platform is supported, file reads are not done <em>by</em>
profiler <em>during</em> profiling (and charged to user's code!).
<P>
</DD>
<DT><STRONG>Speed increased:</STRONG></DT>
<DD>Overhead CPU cost was reduced by more than a factor of two (perhaps a
factor of five), lightweight profiler module is all that must be
loaded, and the report generating module (<tt class="module">pstats</tt>) is not needed
during profiling.
<P>
</DD>
<DT><STRONG>Recursive functions support:</STRONG></DT>
<DD>Cumulative times in recursive functions are correctly calculated;
recursive entries are counted.
<P>
</DD>
<DT><STRONG>Large growth in report generating UI:</STRONG></DT>
<DD>Distinct profiles runs can be added together forming a comprehensive
report; functions that import statistics take arbitrary lists of
files; sorting criteria is now based on keywords (instead of 4 integer
options); reports shows what functions were profiled as well as what
profile file was referenced; output format has been improved.
<P>
</DD>
</DL>
<P>
<DIV CLASS="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="10.1 Introduction to the"
href="node450.html"><img src='../icons/previous.png'
border='0' height='32' alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="10. The Python Profiler"
href="profile.html"><img src='../icons/up.png'
border='0' height='32' alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="10.3 Instant Users Manual"
href="profile-instant.html"><img src='../icons/next.png'
border='0' height='32' alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
href="contents.html"><img src='../icons/contents.png'
border='0' height='32' alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
border='0' height='32' alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
href="genindex.html"><img src='../icons/index.png'
border='0' height='32' alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="node450.html">10.1 Introduction to the</A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="profile.html">10. The Python Profiler</A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="profile-instant.html">10.3 Instant Users Manual</A>
</div>
</div>
<hr />
<span class="release-info">Release 2.4.3, documentation updated on 29 March 2006.</span>
</DIV>
<!--End of Navigation Panel-->
<ADDRESS>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</ADDRESS>
</BODY>
</HTML>