Re: [boost] "Small buffer optimization" for boost::function?

From: Alex Besogonov (cyberax_at_[hidden])
Date: 2005-12-28 04:15:26

Vladimir Prus wrote:
>> I don't have any problem with boost::function speed of invocations
>> (though FastDelegate is two times faster).
> I see. Still, would be nice to see specific numbers.
I've attached a test program (you need FastDelegate from 
http://www.codeproject.com/cpp/FastDelegate.asp to compile it).

Results:
=========================
C:\temp\delegates>gcc -O3 -funroll-loops -fomit-frame-pointer test.cpp 
-Ic:/tools/boost -lstdc++
C:\temp\delegates>a.exe
Time elapsed for FastDelegate: 1.191000 (sec)
Time elapsed for simple bind: 0.010000 (sec)
Time elapsed for bind+function: 33.118000 (sec)
Time elapsed for pure function invocation: 3.705000 (sec)
=========================
(GCC 4.1.0 was used)

You can see that boost::function + boost::bind is an order of magnitude 
slower than FastDelegate. Even a mere invocation of a boost::function is 
slower than complete bind+invoke for FastDelegate.

-- 
With respect,
             Alex Besogonov (cyberax_at_[hidden])

#include <stdio.h>
#include "FastDelegate.h"
#include <boost/timer.hpp>
#include <boost/bind.hpp>
#include <boost/function.hpp>

class Test
{
public:
        void func(int param)
        {
                int i=0;
                i=param+1;
        }
};

using namespace fastdelegate;

int main(void)
{
    typedef FastDelegate1<int> IntMyDelegate;
    Test test;

    boost::timer t;
    for(int f=0;f<100000000;f++)
    {
                IntMyDelegate newdeleg;
            newdeleg = MakeDelegate(&test, &Test::func);
            newdeleg(f);
        }
        printf("Time elapsed for FastDelegate: %f (sec)\n",t.elapsed());

    boost::timer t2;
    for(int f=0;f<100000000;f++)
    {
                boost::bind(&Test::func,&test,_1)(f);
        }
        printf("Time elapsed for simple bind: %f (sec)\n",t2.elapsed());

    boost::timer t3;
    for(int f=0;f<100000000;f++)
    {
                boost::function<void(int)> func=boost::bind(&Test::func,&test,_1);
                func(f);
        }
        printf("Time elapsed for bind+function: %f (sec)\n",t3.elapsed());

    boost::timer t4;
    boost::function<void(int)> func=boost::bind(&Test::func,&test,_1);
    for(int f=0;f<100000000;f++)
    {		
                func(f);
        }
        printf("Time elapsed for pure function invocation: %f (sec)\n",t4.elapsed());
    
        return 0;
}