1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- This file documents the gprof profiler of the GNU system. 4 5Copyright (C) 1988-2021 Free Software Foundation, Inc. 6 7Permission is granted to copy, distribute and/or modify this document 8under the terms of the GNU Free Documentation License, Version 1.3 9or any later version published by the Free Software Foundation; 10with no Invariant Sections, with no Front-Cover Texts, and with no 11Back-Cover Texts. A copy of the license is included in the 12section entitled "GNU Free Documentation License". 13 --> 14<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> 15<head> 16<title>GNU gprof: Flat Profile</title> 17 18<meta name="description" content="GNU gprof: Flat Profile"> 19<meta name="keywords" content="GNU gprof: Flat Profile"> 20<meta name="resource-type" content="document"> 21<meta name="distribution" content="global"> 22<meta name="Generator" content="makeinfo"> 23<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 24<link href="index.html#Top" rel="start" title="Top"> 25<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 26<link href="Output.html#Output" rel="up" title="Output"> 27<link href="Call-Graph.html#Call-Graph" rel="next" title="Call Graph"> 28<link href="Output.html#Output" rel="previous" title="Output"> 29<style type="text/css"> 30<!-- 31a.summary-letter {text-decoration: none} 32blockquote.smallquotation {font-size: smaller} 33div.display {margin-left: 3.2em} 34div.example {margin-left: 3.2em} 35div.indentedblock {margin-left: 3.2em} 36div.lisp {margin-left: 3.2em} 37div.smalldisplay {margin-left: 3.2em} 38div.smallexample {margin-left: 3.2em} 39div.smallindentedblock {margin-left: 3.2em; font-size: smaller} 40div.smalllisp {margin-left: 3.2em} 41kbd {font-style:oblique} 42pre.display {font-family: inherit} 43pre.format {font-family: inherit} 44pre.menu-comment {font-family: serif} 45pre.menu-preformatted {font-family: serif} 46pre.smalldisplay {font-family: inherit; font-size: smaller} 47pre.smallexample {font-size: smaller} 48pre.smallformat {font-family: inherit; font-size: smaller} 49pre.smalllisp {font-size: smaller} 50span.nocodebreak {white-space:nowrap} 51span.nolinebreak {white-space:nowrap} 52span.roman {font-family:serif; font-weight:normal} 53span.sansserif {font-family:sans-serif; font-weight:normal} 54ul.no-bullet {list-style: none} 55--> 56</style> 57 58 59</head> 60 61<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> 62<a name="Flat-Profile"></a> 63<div class="header"> 64<p> 65Next: <a href="Call-Graph.html#Call-Graph" accesskey="n" rel="next">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> 66</div> 67<hr> 68<a name="The-Flat-Profile"></a> 69<h3 class="section">5.1 The Flat Profile</h3> 70<a name="index-flat-profile"></a> 71 72<p>The <em>flat profile</em> shows the total amount of time your program 73spent executing each function. Unless the ‘<samp>-z</samp>’ option is given, 74functions with no apparent time spent in them, and no apparent calls 75to them, are not mentioned. Note that if a function was not compiled 76for profiling, and didn’t run long enough to show up on the program 77counter histogram, it will be indistinguishable from a function that 78was never called. 79</p> 80<p>This is part of a flat profile for a small program: 81</p> 82<div class="smallexample"> 83<pre class="smallexample">Flat profile: 84 85Each sample counts as 0.01 seconds. 86 % cumulative self self total 87 time seconds seconds calls ms/call ms/call name 88 33.34 0.02 0.02 7208 0.00 0.00 open 89 16.67 0.03 0.01 244 0.04 0.12 offtime 90 16.67 0.04 0.01 8 1.25 1.25 memccpy 91 16.67 0.05 0.01 7 1.43 1.43 write 92 16.67 0.06 0.01 mcount 93 0.00 0.06 0.00 236 0.00 0.00 tzset 94 0.00 0.06 0.00 192 0.00 0.00 tolower 95 0.00 0.06 0.00 47 0.00 0.00 strlen 96 0.00 0.06 0.00 45 0.00 0.00 strchr 97 0.00 0.06 0.00 1 0.00 50.00 main 98 0.00 0.06 0.00 1 0.00 0.00 memcpy 99 0.00 0.06 0.00 1 0.00 10.11 print 100 0.00 0.06 0.00 1 0.00 0.00 profil 101 0.00 0.06 0.00 1 0.00 50.00 report 102… 103</pre></div> 104 105<p>The functions are sorted first by decreasing run-time spent in them, 106then by decreasing number of calls, then alphabetically by name. The 107functions ‘<samp>mcount</samp>’ and ‘<samp>profil</samp>’ are part of the profiling 108apparatus and appear in every flat profile; their time gives a measure of 109the amount of overhead due to profiling. 110</p> 111<p>Just before the column headers, a statement appears indicating 112how much time each sample counted as. 113This <em>sampling period</em> estimates the margin of error in each of the time 114figures. A time figure that is not much larger than this is not 115reliable. In this example, each sample counted as 0.01 seconds, 116suggesting a 100 Hz sampling rate. 117The program’s total execution time was 0.06 118seconds, as indicated by the ‘<samp>cumulative seconds</samp>’ field. Since 119each sample counted for 0.01 seconds, this means only six samples 120were taken during the run. Two of the samples occurred while the 121program was in the ‘<samp>open</samp>’ function, as indicated by the 122‘<samp>self seconds</samp>’ field. Each of the other four samples 123occurred one each in ‘<samp>offtime</samp>’, ‘<samp>memccpy</samp>’, ‘<samp>write</samp>’, 124and ‘<samp>mcount</samp>’. 125Since only six samples were taken, none of these values can 126be regarded as particularly reliable. 127In another run, 128the ‘<samp>self seconds</samp>’ field for 129‘<samp>mcount</samp>’ might well be ‘<samp>0.00</samp>’ or ‘<samp>0.02</samp>’. 130See <a href="Sampling-Error.html#Sampling-Error">Statistical Sampling Error</a>, 131for a complete discussion. 132</p> 133<p>The remaining functions in the listing (those whose 134‘<samp>self seconds</samp>’ field is ‘<samp>0.00</samp>’) didn’t appear 135in the histogram samples at all. However, the call graph 136indicated that they were called, so therefore they are listed, 137sorted in decreasing order by the ‘<samp>calls</samp>’ field. 138Clearly some time was spent executing these functions, 139but the paucity of histogram samples prevents any 140determination of how much time each took. 141</p> 142<p>Here is what the fields in each line mean: 143</p> 144<dl compact="compact"> 145<dt><code>% time</code></dt> 146<dd><p>This is the percentage of the total execution time your program spent 147in this function. These should all add up to 100%. 148</p> 149</dd> 150<dt><code>cumulative seconds</code></dt> 151<dd><p>This is the cumulative total number of seconds the computer spent 152executing this functions, plus the time spent in all the functions 153above this one in this table. 154</p> 155</dd> 156<dt><code>self seconds</code></dt> 157<dd><p>This is the number of seconds accounted for by this function alone. 158The flat profile listing is sorted first by this number. 159</p> 160</dd> 161<dt><code>calls</code></dt> 162<dd><p>This is the total number of times the function was called. If the 163function was never called, or the number of times it was called cannot 164be determined (probably because the function was not compiled with 165profiling enabled), the <em>calls</em> field is blank. 166</p> 167</dd> 168<dt><code>self ms/call</code></dt> 169<dd><p>This represents the average number of milliseconds spent in this 170function per call, if this function is profiled. Otherwise, this field 171is blank for this function. 172</p> 173</dd> 174<dt><code>total ms/call</code></dt> 175<dd><p>This represents the average number of milliseconds spent in this 176function and its descendants per call, if this function is profiled. 177Otherwise, this field is blank for this function. 178This is the only field in the flat profile that uses call graph analysis. 179</p> 180</dd> 181<dt><code>name</code></dt> 182<dd><p>This is the name of the function. The flat profile is sorted by this 183field alphabetically after the <em>self seconds</em> and <em>calls</em> 184fields are sorted. 185</p></dd> 186</dl> 187 188<hr> 189<div class="header"> 190<p> 191Next: <a href="Call-Graph.html#Call-Graph" accesskey="n" rel="next">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> 192</div> 193 194 195 196</body> 197</html> 198