You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
121 lines
4.4 KiB
HTML
121 lines
4.4 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- This file documents the gprof profiler of the GNU system.
|
|
|
|
Copyright (C) 1988-2019 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3
|
|
or any later version published by the Free Software Foundation;
|
|
with no Invariant Sections, with no Front-Cover Texts, and with no
|
|
Back-Cover Texts. A copy of the license is included in the
|
|
section entitled "GNU Free Documentation License".
|
|
-->
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>How do I? (GNU gprof)</title>
|
|
|
|
<meta name="description" content="How do I? (GNU gprof)">
|
|
<meta name="keywords" content="How do I? (GNU gprof)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="index.html#Top" rel="up" title="Top">
|
|
<link href="Incompatibilities.html#Incompatibilities" rel="next" title="Incompatibilities">
|
|
<link href="Assumptions.html#Assumptions" rel="prev" title="Assumptions">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<a name="How-do-I_003f"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Incompatibilities.html#Incompatibilities" accesskey="n" rel="next">Incompatibilities</a>, Previous: <a href="Inaccuracy.html#Inaccuracy" accesskey="p" rel="prev">Inaccuracy</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="Answers-to-Common-Questions"></a>
|
|
<h2 class="chapter">7 Answers to Common Questions</h2>
|
|
|
|
<dl compact="compact">
|
|
<dt>How can I get more exact information about hot spots in my program?</dt>
|
|
<dd>
|
|
<p>Looking at the per-line call counts only tells part of the story.
|
|
Because <code>gprof</code> can only report call times and counts by function,
|
|
the best way to get finer-grained information on where the program
|
|
is spending its time is to re-factor large functions into sequences
|
|
of calls to smaller ones. Beware however that this can introduce
|
|
artificial hot spots since compiling with ‘<samp>-pg</samp>’ adds a significant
|
|
overhead to function calls. An alternative solution is to use a
|
|
non-intrusive profiler, e.g. oprofile.
|
|
</p>
|
|
</dd>
|
|
<dt>How do I find which lines in my program were executed the most times?</dt>
|
|
<dd>
|
|
<p>Use the <code>gcov</code> program.
|
|
</p>
|
|
</dd>
|
|
<dt>How do I find which lines in my program called a particular function?</dt>
|
|
<dd>
|
|
<p>Use ‘<samp>gprof -l</samp>’ and lookup the function in the call graph.
|
|
The callers will be broken down by function and line number.
|
|
</p>
|
|
</dd>
|
|
<dt>How do I analyze a program that runs for less than a second?</dt>
|
|
<dd>
|
|
<p>Try using a shell script like this one:
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">for i in `seq 1 100`; do
|
|
fastprog
|
|
mv gmon.out gmon.out.$i
|
|
done
|
|
|
|
gprof -s fastprog gmon.out.*
|
|
|
|
gprof fastprog gmon.sum
|
|
</pre></div>
|
|
|
|
<p>If your program is completely deterministic, all the call counts
|
|
will be simple multiples of 100 (i.e., a function called once in
|
|
each run will appear with a call count of 100).
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|