Excluding a function from gprof results

Question

I want to exclude some functions from the output generated by gprof. In other words, I do not want them to be included when calculating percentage time spent by each function during execution. I read at one place -E option can be used.

However I'm using gprof -E function_to_be_exluded my_program_name, but nothing happens. The manual says it is depreciated and you should use symspecs instead. However, I have wasted half an hour trying to figure out how to achieve it with symspecs, but no luck. Anyone can kindly help me in this.

Answer 1

Exactly, gprof -e -E are deprecated and superseded by usage of newer relevant options that have argument - symspecs. So try using:

gprof --no-time=symspec 

The -n option causes "gprof", in its call graph analysis, not to propagate times for
symbols matching symspec.

e.g.

gprof --no-time=name_of_function_you_dont_want_to_profile.

Use this along with your other gprof options (-E -e definitely ruled out)

Answer 2

According to the man:

• for display flat profile and exclude function from it you need use -P option:

  gprof main gmon.out -Pfunction_name
  

• for display call graph and exclude function from it you need use -Q option:

  gprof main gmon.out -Qfunction_name
  

This options can be repeated and used in the same time:

gprof main gmon.out -Pfunction_name -Qfunction_name -Qother_function_name

If you need exclude function from one report but not exclude any function from other you need use -p or -q options.

Example:

Create program:

#include <stdio.h>
#include <stdlib.h>

void func_a () {printf ("%s ",__FUNCTION__);}
void func_b () {printf ("%s ",__FUNCTION__);}
void func_c () {printf ("%s ",__FUNCTION__);}

int main ()
{
    func_a ();
    func_b ();
    func_c ();
    return EXIT_SUCCESS;
}

Compile it: gcc main.c -pg -o main

And launch:

$ ./main
func_a func_b func_c

Generate profile reports:

• If you need print only flat profile you need call:

  $ gprof main gmon.out -b -p  
    %   cumulative   self              self     total             
   time   seconds   seconds    calls  Ts/call  Ts/call  name      
    0.00      0.00     0.00        1     0.00     0.00  func_a  
    0.00      0.00     0.00        1     0.00     0.00  func_b  
    0.00      0.00     0.00        1     0.00     0.00  func_c
  

• If you need print flat profile excluding functions func_a and func_c and full call graph you need call:

  $ gprof main gmon.out -b -Pfunc_a -Pfunc_c -q
    %   cumulative   self              self     total           
   time   seconds   seconds    calls  Ts/call  Ts/call  name    
    0.00      0.00     0.00        1     0.00     0.00  func_b
  
  index % time    self  children    called     name
                  0.00    0.00       1/1           main [9]
  [1]      0.0    0.00    0.00       1         func_a [1]
  -----------------------------------------------
                  0.00    0.00       1/1           main [9]
  [2]      0.0    0.00    0.00       1         func_b [2]
  -----------------------------------------------
                  0.00    0.00       1/1           main [9]
  [3]      0.0    0.00    0.00       1         func_c [3]
  -----------------------------------------------
  

• If you need print flat profile excluding functions func_a and func_c and call graph excluding func_b you need call:

  $ gprof main gmon.out -b -Pfunc_a -Pfunc_c -Qfunc_b
    %   cumulative   self              self     total           
   time   seconds   seconds    calls  Ts/call  Ts/call  name    
    0.00      0.00     0.00        1     0.00     0.00  func_b
  
  index % time    self  children    called     name
                  0.00    0.00       1/1           main [9]
  [1]      0.0    0.00    0.00       1         func_a [1]
  -----------------------------------------------
                  0.00    0.00       1/1           main [9]  
  [3]      0.0    0.00    0.00       1         func_c [3]
  -----------------------------------------------
  

Answer 3

Unless I've misunderstood what you're asking...

gprof a.out --no-time=function_name

works for me.