policy.cpp

#include <iostream>
#include <cstdlib>

using namespace std;

typedef double float64_t;
typedef unsigned long index_t;

template <class T>
struct ComputeSquare
{
	T compute(T n)
	{
		return n*n;
	}
protected:
	~ComputeSquare() {}
};

template <class T>
struct ComputeCube
{
	T compute(T n)
	{
		return n*n*n;
	}
protected:
	~ComputeCube() {}
};

template <template <class> class Compute>
struct Computation : public Compute<float64_t>
{
};

int main(int argc, char** argv)
{
	if (argc < 2)
		exit(1);
	const index_t iter = atol(argv[1]);
	Computation<ComputeSquare>* sq = new Computation<ComputeSquare>();
	for (index_t i = 1; i <= iter; ++i)
	{
		sq->compute(i-1);
		sq->compute(i);
		sq->compute(i+1);
	}
	delete sq;
	Computation<ComputeCube>* cube = new Computation<ComputeCube>();
	for (index_t i = 1; i <= iter; ++i)
	{
		cube->compute(i-1);
		cube->compute(i);
		cube->compute(i+1);
	}
	delete cube;
	return 0;
}

policy.log

[lambday@lambday.iitb.ac.in policy_virtual]$ time ./a.out 10000000000

real	0m3.203s
user	0m3.200s
sys	0m0.000s

virtual.cpp

#include <iostream>
#include <cstdlib>

using namespace std;

typedef double float64_t;
typedef unsigned long index_t;

template <class T>
struct Computation
{
	virtual T compute(T n) = 0;
	virtual ~Computation() {}
};

struct ComputeSquare : public Computation<float64_t>
{
	virtual float64_t compute(float64_t n)
	{
		return n*n;
	}
	virtual ~ComputeSquare() {}
};

struct ComputeCube : public Computation<float64_t>
{
	virtual float64_t compute(float64_t n)
	{
		return n*n*n;
	}
	virtual ~ComputeCube() {}
};

int main(int argc, char** argv)
{
	if (argc < 2)
		exit(1);
	const index_t iter = atol(argv[1]);
	Computation<float64_t>* sq = new ComputeSquare();
	for (index_t i = 1; i <= iter; ++i)
	{
		sq->compute(i-1);
		sq->compute(i);
		sq->compute(i+1);
	}
	delete sq;
	Computation<float64_t>* cube = new ComputeCube();
	for (index_t i = 1; i <= iter; ++i)
	{
		cube->compute(i-1);
		cube->compute(i);
		cube->compute(i+1);
	}
	delete cube;
	return 0;
}

virtual.log

[lambday@lambday.iitb.ac.in policy_virtual]$ time ./a.out 10000000000

real	3m20.989s
user	3m20.904s
sys	0m0.002s