[Boost-users] [pool] Speed of pool_allocator<>

From: Klaus Nowikow (nowikow_at_[hidden])
Date: 2004-07-01 06:18:15

Hi!

I am in the process of writing a program which has to
handle large numbers (~200000 - 400000) objects of the same class.
These objects will be created and deleted frequently, so I thought
some kind of specialized memory management would be handy.

I wrote a test program (see below) to check what boost.pool would gain
me. The results make me think that I have done something wrong:

debug mode:
    std::allocator        2.17s
    boost::pool_allocator 7.18s

release mode:
    std::allocator        0.11s
    boost::pool_allocator 0.36s

i.e., std::allocator was more than 3 times faster than
boost::pool_allocator (Win2k, 256MB). Any ideas what i have done wrong? See the test
program below.

// MemoryPoolTest.cpp

// Boost includes -------------------------------------------------------------
#include <boost/timer.hpp>
#include <boost/pool/pool_alloc.hpp>

// Std includes ---------------------------------------------------------------
#include <vector>
#include <iostream>

enum
{
        NUM_ELEMENTS	= 3000000
};

template <class Allocator>
double	Test()
{
        std::vector<Allocator::value_type, Allocator>	Vector;
        boost::timer						Timer;

        for(int i = 0; i < NUM_ELEMENTS; ++i)
        {
                Vector.push_back(i);
        }

        return	Timer.elapsed();
}

int main(int argc, char* argv[])
{
        std::cout << "Starting memory pool test" << std::endl;

        double	Time;

        std::cout << "Allocating with boost::pool_allocator<>: ";
        Time	= Test<boost::pool_allocator<int> >();
        std::cout << Time << "s" << std::endl;

        std::cout << "Allocating with std::allocator<>       : ";
        Time	= Test<std::allocator<int> >();
        std::cout << Time << "s" << std::endl;

        return 0;
}