gprof (GNU Profiler)

Overview

gprof is the GNU Profiler that can be used, in combination with compiler flags, to determine where time has been spent during program execution.

Restrictions on use

None

Set up procedure

None

Running the application

Your application needs compiling with -p -g (Intel) or -pg (GNU). When such applications are run they create, or append, to gmon.out. gprof uses the information in this file to give various program profiles. A basic (abridged) example is

ifort -O0 -p -g primes_skel.f90 chkPrime.f90 -o prime_profile.exe
time ./prime_profile.exe > primes.txt

  real	0m2.688s
  user	0m2.654s
  sys	0m0.023s


gprof prime_profile.exe gmon.out 

  Flat profile:

  Each sample counts as 0.01 seconds.
    %   cumulative   self              self     total           
   time   seconds   seconds    calls   s/call   s/call  name    
   69.73      1.56     1.56  1000000     0.00     0.00  chkprime_
   24.66      2.11     0.55                             sqrtf.A
    2.69      2.17     0.06                             cvtas__nan_x
    1.35      2.20     0.03                             sqrtf.L
    0.90      2.22     0.02                             sqrtf
    0.67      2.23     0.02        1     0.02     1.57  MAIN__

This illustrates that nearly 70% of the time was spent in the chkprime() function.

See the man gprof for options available.

Note that production codes should be run under the batch system, not on the login node

More Information