A simple Benchmark based on Primes

PrimeBenchmark

//============================================================================
// Name        : Benchmark.cpp
// Author      : Lars Klein
// Version     : 0.3
// Copyright   : CC
// Description : A simple benchmark based on primes
//============================================================================

#include <iostream>
#include <math.h>

#include "omp.h"

using namespace std;

int main() {

	const int MAX_SIZE=1000000;

	double walltime=omp_get_wtime();
	int i;
	int j;
	int prime;
	int amount = 0;

	int times=10;
	for(int t=0;t<times;t++){

		amount=0;
		# pragma omp parallel private ( i, j, prime )

		# pragma omp for reduction ( + : amount )
		for ( i = 2; i <= MAX_SIZE; i++ ){
			prime = 1;

			for ( j = 2; j <= sqrt(i); j++ ){
				if ( i % j == 0 ){
					prime = 0;
					break;
				}
			}
			amount = amount + prime;
		}
	}

	walltime=omp_get_wtime()-walltime;
	walltime/=times;
	cout<<"number of primes in 2.."<<MAX_SIZE<<" : "<<amount<<endl;
	cout<<"the calculation took: "<<walltime<<endl;
}

compile and run with
g++ -fopenmp Benchmark.cpp -o bench
export OMP_NUM_THREADS=2
./bench

Depending on the shell you use, you might have to replace
export OMP_NUM_THREADS=2
with
set -x OMP_NUM_THREADS=2