{{lastupdated_at}} by {{lastupdated_by}}

h1. How to use valgrind?

Valgrid is a very useful tool for finding bottle necks in the execution of code and to identify where actually the type is spent.

h2. Running an executable with valgrind

<pre>
valgrind --tool=callgrind --dump-instr=yes --collect-jumps=yes gsrvy (args)
</pre>

h2. Running an executable on a specific code zone

Mark the code zone using some macros
<pre><code>
#include <valgrind/callgrind.h>

int main()
{
  foo1();
  CALLGRIND_START_INSTRUMENTATION;
  CALLGRIND_TOGGLE_COLLECT;
  bar1();
  CALLGRIND_TOGGLE_COLLECT;
  CALLGRIND_STOP_INSTRUMENTATION;
  foo2();
  foo3();
}
</code></pre>
and run valgrind as follows
<pre>
valgrind --tool=callgrind --dump-instr=yes --collect-jumps=yes --collect-atstart=no --instr-atstart=no gsrvy (args)
</pre>

h2. Advanced usage

If the @callgrind.out.*@ file is empty call
<pre>
callgrind_control -d [hint [PID/Name]]
</pre>where hint is an arbitrary string you can optionally specify to later be able to distinguish profile dumps.

Check whether instrumentation is turned on using
<pre>
callgrind_control -b
</pre>

You can also decide to switch instrumentation on using
<pre>
callgrind_control -i on
</pre>(and switching off again by specifying "off" instead of "on").

h2. Result visualisation

Use the @kcachegrind@ GUI to visualise the results.