Re: [boost] [signal] performance

From: Arno Wilhelm (arno.wilhelm_at_[hidden])
Date: 2005-12-21 04:54:44

Hello,

Have modified your example a bit and tried it out on my linux machine (fedora core 3) and the performance seems to be even worse.
I use boost 1.32 (1.32.0-5.fc3) and gcc-Version 3.4.4 20050721 (Red Hat 3.4.4-2) on a Intel Pentium 4 CPU 3.00GHz with 2048 kb cache.

# When I compile it with optimization I typically get these values:

 > g++ -O3 -o signal_test main.cc -lboost_signals
 > ./signal_test

Iterations: 10000000

SIGNALS:           sec.: 56 / usec.: 295077
BOOST::FUNCTION:   sec.:  0 / usec.: 176564
FUNCTION POINTER:  sec.:  0 / usec.: 41502

# Without optimization it looks like this:

 > g++ -o signal_test main.cc -lboost_signals

./signal_test

Iterations: 10000000

SIGNALS:           sec.: 70 / usec.: 26187
BOOST::FUNCTION:   sec.:  0 / usec.: 244619
FUNCTION POINTER:  sec.:  0 / usec.: 53574

And I always thought signals ought to be fast :-).

Here is the code I used for the test:

------------------------------- snip -------------------------------
#include <boost/function.hpp>
#include <boost/signals.hpp>
#include <iostream>
#include <sys/time.h>

using namespace std;

void do_nothing()
{
}

int main()
{
     unsigned int counter = 0;
     const unsigned int MAX_ITERATION = 10000000;
     struct timeval t_start;
     struct timeval t_end;

     boost::function<void (void)> f = do_nothing;
     void (*pf)(void) = &do_nothing;
     boost::signal<void (void)> s;
     s.connect(&do_nothing);

     cerr << "\nIterations: " << MAX_ITERATION << endl << endl;
     cerr << "SIGNALS:          ";
     gettimeofday( &t_start, 0 );
     for( counter = 0; counter < MAX_ITERATION; ++counter )
         {
         s();
         }
     gettimeofday( &t_end, 0 );
     cerr << "sec.: " << ( t_end.tv_sec - t_start.tv_sec ) << " / usec.: " << ( t_end.tv_usec - t_start.tv_usec ) << endl;

     cerr << "BOOST::FUNCTION:  ";
     gettimeofday( &t_start, 0 );
     for( counter = 0; counter < MAX_ITERATION; ++counter )
         {
         f();
         }
     gettimeofday( &t_end, 0 );
     cerr << "sec.: " << ( t_end.tv_sec - t_start.tv_sec ) << " / usec.: " << ( t_end.tv_usec - t_start.tv_usec ) << endl;

     cerr << "FUNCTION POINTER: ";
     gettimeofday( &t_start, 0 );
     for( counter = 0; counter < MAX_ITERATION; ++counter )
         {
         pf();
         }
     gettimeofday( &t_end, 0 );
     cerr << "sec.: " << ( t_end.tv_sec - t_start.tv_sec ) << " / usec.: " << ( t_end.tv_usec - t_start.tv_usec ) << endl;

     return 0;
}
------------------------------- snip -------------------------------

regards,

Arno