I need to profile a program to see whether any changes need to be made regarding performance. I suspect there is a need, but measuring first is the way to go. This is not that program, but it illustrates the problem I'm having:

#include <stdio.h> int main (int argc, char** argv) { FILE* fp = fopen ("trivial.c", "r"); if (fp) { char line[80]; while (fgets (line, 80, fp)) printf (line); fclose (fp); } return 0; } 

Here's what I did with it:

% gcc trivial.c -pg -o trivial % ./trivial ... % gprof trivial gmon.out 

Granted, this is a trivial program, but I would have thought it would make some kind of blip on the profiling radar. It didn't:

 called/total parents index %time self descendents called+self name index called/total children 0.00 0.00 1/1 __start [1704] [105] 0.0 0.00 0.00 1 _main [105] ----------------------------------------------- % cumulative self self total time seconds seconds calls ms/call ms/call name 0.0 0.00 0.00 1 0.00 0.00 _main [105] Index by function name [105] _main 

Can anyone guide me here? I would like the output to reflect that it called fgets and printf at least 14 times, and it did hit the disk after all - there should be some measured time, surely.

When I run the same command on the real program, I get more functions listed, but even then it is not a complete list - just a sample.

Perhaps gprof is not the right tool to use. What is?

This is on OS X Leopard.