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| <title>GNU gprof: Call Graph</title> |
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| <a name="Call-Graph"></a> |
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| Next: <a href="Line_002dby_002dline.html#Line_002dby_002dline" accesskey="n" rel="next">Line-by-line</a>, Previous: <a href="Flat-Profile.html#Flat-Profile" accesskey="p" rel="prev">Flat Profile</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> |
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| <a name="The-Call-Graph"></a> |
| <h3 class="section">5.2 The Call Graph</h3> |
| <a name="index-call-graph"></a> |
| |
| <p>The <em>call graph</em> shows how much time was spent in each function |
| and its children. From this information, you can find functions that, |
| while they themselves may not have used much time, called other |
| functions that did use unusual amounts of time. |
| </p> |
| <p>Here is a sample call from a small program. This call came from the |
| same <code>gprof</code> run as the flat profile example in the previous |
| section. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">granularity: each sample hit covers 2 byte(s) for 20.00% of 0.05 seconds |
| |
| index % time self children called name |
| <spontaneous> |
| [1] 100.0 0.00 0.05 start [1] |
| 0.00 0.05 1/1 main [2] |
| 0.00 0.00 1/2 on_exit [28] |
| 0.00 0.00 1/1 exit [59] |
| ----------------------------------------------- |
| 0.00 0.05 1/1 start [1] |
| [2] 100.0 0.00 0.05 1 main [2] |
| 0.00 0.05 1/1 report [3] |
| ----------------------------------------------- |
| 0.00 0.05 1/1 main [2] |
| [3] 100.0 0.00 0.05 1 report [3] |
| 0.00 0.03 8/8 timelocal [6] |
| 0.00 0.01 1/1 print [9] |
| 0.00 0.01 9/9 fgets [12] |
| 0.00 0.00 12/34 strncmp <cycle 1> [40] |
| 0.00 0.00 8/8 lookup [20] |
| 0.00 0.00 1/1 fopen [21] |
| 0.00 0.00 8/8 chewtime [24] |
| 0.00 0.00 8/16 skipspace [44] |
| ----------------------------------------------- |
| [4] 59.8 0.01 0.02 8+472 <cycle 2 as a whole> [4] |
| 0.01 0.02 244+260 offtime <cycle 2> [7] |
| 0.00 0.00 236+1 tzset <cycle 2> [26] |
| ----------------------------------------------- |
| </pre></div> |
| |
| <p>The lines full of dashes divide this table into <em>entries</em>, one for each |
| function. Each entry has one or more lines. |
| </p> |
| <p>In each entry, the primary line is the one that starts with an index number |
| in square brackets. The end of this line says which function the entry is |
| for. The preceding lines in the entry describe the callers of this |
| function and the following lines describe its subroutines (also called |
| <em>children</em> when we speak of the call graph). |
| </p> |
| <p>The entries are sorted by time spent in the function and its subroutines. |
| </p> |
| <p>The internal profiling function <code>mcount</code> (see <a href="Flat-Profile.html#Flat-Profile">The |
| Flat Profile</a>) is never mentioned in the call graph. |
| </p> |
| <table class="menu" border="0" cellspacing="0"> |
| <tr><td align="left" valign="top">• <a href="Primary.html#Primary" accesskey="1">Primary</a>:</td><td> </td><td align="left" valign="top">Details of the primary line’s contents. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Callers.html#Callers" accesskey="2">Callers</a>:</td><td> </td><td align="left" valign="top">Details of caller-lines’ contents. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Subroutines.html#Subroutines" accesskey="3">Subroutines</a>:</td><td> </td><td align="left" valign="top">Details of subroutine-lines’ contents. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Cycles.html#Cycles" accesskey="4">Cycles</a>:</td><td> </td><td align="left" valign="top">When there are cycles of recursion, |
| such as <code>a</code> calls <code>b</code> calls <code>a</code>… |
| </td></tr> |
| </table> |
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