Profiling with gcc and gprof

The GNU gprof profiler, gprof, allows you to profile your code. To use it, you need to perform the following steps:

1. Build the application with settings for generating profiling information
2. Generate profiling information by running the built application
3. View the generated profiling information with gprof

In order to build the application with settings for generating profiling information, we add the -pg flag. So, for example, we could use

$ gcc -pg *.cpp -o app

or

$ gcc -O2 -pg *.cpp -o app

and so forth.

Once the application, say app, is built, execute it as usual:

$ ./app

This should produce a file called gmon.out.

To see the profiling results, now run

$ gprof app gmon.out

(note that we provide both the application as well as the generated output).

Of course, you can also pipe or redirect:

$ gprof app gmon.out | less

and so forth.

The result of the last command should be a table, whose rows are the functions, and whose columns indicate the number of calls, total time spent, self time spent (that is, time spent in the function excluding calls to children).