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<h2 class="chapter">7 Answers to Common Questions</h2>
<dl>
<dt>How can I get more exact information about hot spots in my program?<dd>
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><span class="samp">-pg</span></samp>’ adds a significant
overhead to function calls. An alternative solution is to use a
non-intrusive profiler, e.g. oprofile.
<br><dt>How do I find which lines in my program were executed the most times?<dd>
Use the <code>gcov</code> program.
<br><dt>How do I find which lines in my program called a particular function?<dd>
Use ‘<samp><span class="samp">gprof -l</span></samp>’ and lookup the function in the call graph.
The callers will be broken down by function and line number.
<br><dt>How do I analyze a program that runs for less than a second?<dd>
Try using a shell script like this one:
<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>
<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).
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