/*
 * Test program to measure the overhead of OpenMP parallel
 *     from OdinMP/CCp report by Christian Brunschen at Lund
 */

#include <sys/time.h>
#include <unistd.h>
#include <stdlib.h>
#include "omniConfig.h"
#include <strings.h>

int spin_factor = 1000;

void * nop(void * p)
{
    return p;
}

void spin(double jLimit)
{
    int  i;
    double  j;
    double  d;

    for( i = 0 ; i < spin_factor ; i++ ){
	for( j = 0.0 ; j < jLimit ; j += 1.0 ){
	    nop(&d);
	}
    }
}

double t()
{
    struct timeval tv;

    gettimeofday(&tv, ((void *) 0));
    return (double)tv.tv_sec + (double)tv.tv_usec / 1000000.0;
}

int main(int argc, char ** argv)
{
    int  i;
    int  num = 100;
    double  t0, t1, t2, t3, dt1t0, dt3t2;
    double  dt1t0_iter, dt3t2_iter;
    double  diff, diff_iter;

    for( i = 1 ; i < argc ; i++ ){
	if ( !strcmp(argv[i], "-n") ){
	    if ( argc <= (i+1) ){
		fprintf(stderr, "need argument to '-n'\n");
		exit(1);
	    }
	    num = atoi(argv[++i]);
	}
	else if ( !strcmp(argv[i], "-f") ){
	    if ( argc <= (i+1) ){
		fprintf(stderr, "need argument to '-f'\n");
		exit(1);
	    }
	    spin_factor = atoi(argv[++i]);
	}
    }

    printf("Parallel:\n");
    t0 = t();
    for( i = 0 ; i < num ; i++ ){
#pragma omp parallel
	spin(1000.0);
    }
    t1 = t();
    dt1t0 = t1 - t0;
    dt1t0_iter = dt1t0 / num;
    printf("time              : %15.9g s = %15.9g ms = %15.9g us\n",
	   dt1t0, dt1t0*1000.0, dt1t0*1000000.0);
    printf("time/iteration    : %15.9g s = %15.9g ms = %15.9g us\n",
	   dt1t0_iter, dt1t0_iter*1000.0, dt1t0_iter*1000000.0);

    printf("Sequential:\n");
    t2 = t();
    for( i = 0 ; i < num ; i++ ){
	spin(1000.0);
    }
    t3 = t();
    dt3t2 = t3 - t2;
    dt3t2_iter = dt3t2 / num;

    printf("time              : %15.9g s = %15.9g ms = %15.9g us\n",
	   dt3t2, dt3t2*1000.0, dt3t2*1000000.0);
    printf("time/iteration    : %15.9g s = %15.9g ms = %15.9g us\n",
	   dt3t2_iter, dt3t2_iter*1000.0, dt3t2_iter*1000000.0);

    diff = dt1t0 - dt3t2;
    diff_iter = dt1t0_iter - dt3t2_iter;
    printf("OpenMP verhead:\n");
    printf("overhead          : %15.9g s = %15.9g ms = %15.9g us\n",
	   diff, diff*1000.0, diff*1000000.0);
    printf("overhead/iteration: %15.9g s = %15.9g ms = %15.9g us\n",
	   diff_iter, diff_iter*1000.0, diff_iter*1000000.0);
}