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.
175 lines
7.4 KiB
HTML
175 lines
7.4 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>Line-by-line (GNU gprof)</title>
|
|
|
|
<meta name="description" content="Line-by-line (GNU gprof)">
|
|
<meta name="keywords" content="Line-by-line (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="Output.html#Output" rel="up" title="Output">
|
|
<link href="Annotated-Source.html#Annotated-Source" rel="next" title="Annotated Source">
|
|
<link href="Cycles.html#Cycles" rel="prev" title="Cycles">
|
|
<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="Line_002dby_002dline"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Annotated-Source.html#Annotated-Source" accesskey="n" rel="next">Annotated Source</a>, Previous: <a href="Call-Graph.html#Call-Graph" accesskey="p" rel="prev">Call Graph</a>, Up: <a href="Output.html#Output" accesskey="u" rel="up">Output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="Line_002dby_002dline-Profiling"></a>
|
|
<h3 class="section">5.3 Line-by-line Profiling</h3>
|
|
|
|
<p><code>gprof</code>’s ‘<samp>-l</samp>’ option causes the program to perform
|
|
<em>line-by-line</em> profiling. In this mode, histogram
|
|
samples are assigned not to functions, but to individual
|
|
lines of source code. This only works with programs compiled with
|
|
older versions of the <code>gcc</code> compiler. Newer versions of <code>gcc</code>
|
|
use a different program - <code>gcov</code> - to display line-by-line
|
|
profiling information.
|
|
</p>
|
|
<p>With the older versions of <code>gcc</code> the program usually has to be
|
|
compiled with a ‘<samp>-g</samp>’ option, in addition to ‘<samp>-pg</samp>’, in order
|
|
to generate debugging symbols for tracking source code lines.
|
|
Note, in much older versions of <code>gcc</code> the program had to be
|
|
compiled with the ‘<samp>-a</samp>’ command-line option as well.
|
|
</p>
|
|
<p>The flat profile is the most useful output table
|
|
in line-by-line mode.
|
|
The call graph isn’t as useful as normal, since
|
|
the current version of <code>gprof</code> does not propagate
|
|
call graph arcs from source code lines to the enclosing function.
|
|
The call graph does, however, show each line of code
|
|
that called each function, along with a count.
|
|
</p>
|
|
<p>Here is a section of <code>gprof</code>’s output, without line-by-line profiling.
|
|
Note that <code>ct_init</code> accounted for four histogram hits, and
|
|
13327 calls to <code>init_block</code>.
|
|
</p>
|
|
<div class="smallexample">
|
|
<pre class="smallexample">Flat profile:
|
|
|
|
Each sample counts as 0.01 seconds.
|
|
% cumulative self self total
|
|
time seconds seconds calls us/call us/call name
|
|
30.77 0.13 0.04 6335 6.31 6.31 ct_init
|
|
|
|
|
|
Call graph (explanation follows)
|
|
|
|
|
|
granularity: each sample hit covers 4 byte(s) for 7.69% of 0.13 seconds
|
|
|
|
index % time self children called name
|
|
|
|
0.00 0.00 1/13496 name_too_long
|
|
0.00 0.00 40/13496 deflate
|
|
0.00 0.00 128/13496 deflate_fast
|
|
0.00 0.00 13327/13496 ct_init
|
|
[7] 0.0 0.00 0.00 13496 init_block
|
|
|
|
</pre></div>
|
|
|
|
<p>Now let’s look at some of <code>gprof</code>’s output from the same program run,
|
|
this time with line-by-line profiling enabled. Note that <code>ct_init</code>’s
|
|
four histogram hits are broken down into four lines of source code—one hit
|
|
occurred on each of lines 349, 351, 382 and 385. In the call graph,
|
|
note how
|
|
<code>ct_init</code>’s 13327 calls to <code>init_block</code> are broken down
|
|
into one call from line 396, 3071 calls from line 384, 3730 calls
|
|
from line 385, and 6525 calls from 387.
|
|
</p>
|
|
<div class="smallexample">
|
|
<pre class="smallexample">Flat profile:
|
|
|
|
Each sample counts as 0.01 seconds.
|
|
% cumulative self
|
|
time seconds seconds calls name
|
|
7.69 0.10 0.01 ct_init (trees.c:349)
|
|
7.69 0.11 0.01 ct_init (trees.c:351)
|
|
7.69 0.12 0.01 ct_init (trees.c:382)
|
|
7.69 0.13 0.01 ct_init (trees.c:385)
|
|
|
|
|
|
Call graph (explanation follows)
|
|
|
|
|
|
granularity: each sample hit covers 4 byte(s) for 7.69% of 0.13 seconds
|
|
|
|
% time self children called name
|
|
|
|
0.00 0.00 1/13496 name_too_long (gzip.c:1440)
|
|
0.00 0.00 1/13496 deflate (deflate.c:763)
|
|
0.00 0.00 1/13496 ct_init (trees.c:396)
|
|
0.00 0.00 2/13496 deflate (deflate.c:727)
|
|
0.00 0.00 4/13496 deflate (deflate.c:686)
|
|
0.00 0.00 5/13496 deflate (deflate.c:675)
|
|
0.00 0.00 12/13496 deflate (deflate.c:679)
|
|
0.00 0.00 16/13496 deflate (deflate.c:730)
|
|
0.00 0.00 128/13496 deflate_fast (deflate.c:654)
|
|
0.00 0.00 3071/13496 ct_init (trees.c:384)
|
|
0.00 0.00 3730/13496 ct_init (trees.c:385)
|
|
0.00 0.00 6525/13496 ct_init (trees.c:387)
|
|
[6] 0.0 0.00 0.00 13496 init_block (trees.c:408)
|
|
|
|
</pre></div>
|
|
|
|
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Annotated-Source.html#Annotated-Source" accesskey="n" rel="next">Annotated Source</a>, Previous: <a href="Call-Graph.html#Call-Graph" accesskey="p" rel="prev">Call Graph</a>, Up: <a href="Output.html#Output" accesskey="u" rel="up">Output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|