gprof profiler does not print the time summary

Question

I created a simple program:

#include <unistd.h>

void ssleep(unsigned int s)
{
  usleep(1000000*s);
}

int main(int, char**)
{
  ssleep(1);
}

After these commands:

sch@sch-K52F:~/test$ g++ -pedantic -Wall main.cpp -pg
sch@sch-K52F:~/test$ ./a.out 
sch@sch-K52F:~/test$ gprof -b a.out > profile

I get a profile without time summary:

  %   cumulative   self              self     total           
 time   seconds   seconds    calls  Ts/call  Ts/call  name    
  0.00      0.00     0.00        1     0.00     0.00  ssleep(unsigned int)

The same situation with any other code. Am I missing something?

My system:

sch@sch-K52F:~/test$ uname -a
Linux sch-K52F 3.2.0-45-generic-pae #70-Ubuntu SMP Wed May 29 20:31:05 UTC 2013 i686 i686 i386 GNU/Linux
sch@sch-K52F:~/test$ gprof -v
GNU gprof (GNU Binutils for Ubuntu) 2.22
Based on BSD gprof, copyright 1983 Regents of the University of California.
This program is free software.  This program has absolutely no warranty.

thank you

---

edit 1)

other example:

 time   seconds   seconds    calls  Ts/call  Ts/call  name
  0.00      0.00     0.00     1482     0.00     0.00  std::_Iter_base<unsigned char*, false>::_S_base(unsigned char*)
  0.00      0.00     0.00     1482     0.00     0.00  std::_Niter_base<unsigned char*>::iterator_type std::__niter_base<unsigned char*>(unsigned char*)
  0.00      0.00     0.00     1247     0.00     0.00  std::_Vector_base<unsigned char, std::allocator<unsigned char> >::_M_get_Tp_allocator()
  0.00      0.00     0.00      988     0.00     0.00  __gnu_cxx::__normal_iterator<unsigned char*, std::vector<unsigned char, std::allocator<unsigned char> > >::base() const
  0.00      0.00     0.00      988     0.00     0.00  std::move_iterator<unsigned char*>::base() const
  0.00      0.00     0.00      988     0.00     0.00  std::vector<unsigned char, std::allocator<unsigned char> >::size() const
  0.00      0.00     0.00      988     0.00     0.00  std::_Iter_base<std::move_iterator<unsigned char*>, true>::_S_base(std::move_iterator<unsigned char*>)
  0.00      0.00     0.00      988     0.00     0.00  std::move_iterator<unsigned char*>::move_iterator(unsigned char*)
  0.00      0.00     0.00      988     0.00     0.00  std::_Miter_base<std::move_iterator<unsigned char*> >::iterator_type std::__miter_base<std::move_iterator<unsigned char*> >(std::move_iterator<unsigned char*>)
  0.00      0.00     0.00      988     0.00     0.00  std::move_iterator<unsigned char*> std::make_move_iterator<unsigned char*>(unsigned char* const&)
  0.00      0.00     0.00      741     0.00     0.00  __gnu_cxx::new_allocator<unsigned char>::max_size() const
  0.00      0.00     0.00      555     0.00     0.00  operator new(unsigned int, void*)
  0.00      0.00     0.00      541     0.00     0.00  void std::_Destroy_aux<true>::__destroy<unsigned char*>(unsigned char*, unsigned char*)
  0.00      0.00     0.00      541     0.00     0.00  std::_Vector_base<unsigned char, std::allocator<unsigned char> >::_M_deallocate(unsigned char*, unsigned int)
  0.00      0.00     0.00      541     0.00     0.00  void std::_Destroy<unsigned char*>(unsigned char*, unsigned char*)

I always get zero time, for any code, any function ;/

Answer 1

This is because sleep() does not count as part of your process execution time, but as sleep. ie your process is put to sleep by the kernel for the requested duration and does not use any CPU cycles. Try with some loop that does real computations. Also, gprof does not seem to take be able to time system calls and other things. It also has other issues . Gprof is meant to compare the performance gain in successive refactoring of your own code, not as an all purpose benchmarking tool.