// 
// parallel for with schedule 
//
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

const int N=100000000;
 
int main()
{
    int A, B, i, nthreads;
	int Nthread[] = {1,2,4,8}, L_Nthread=sizeof(Nthread)/sizeof(Nthread[0]);
	double T[4], T0;	

// schedule: default
    printf("*** Schedule: default ***\n");
	for(i=0; i<L_Nthread; i++)
	{
		nthreads = Nthread[i];
		T0 = clock();
		
        #pragma omp parallel for num_threads(nthreads) private(i,A,B)
		for(i=0; i<N; i++) {  B=rand(); A=2*B; }     

		T[i] = clock() - T0;
		printf("nthreads=%d, time=%.2e, speedup=%.2f\n", nthreads, T[i], T[0]/T[i]);
	}

// schedule: static
    printf("\n*** Schedule: static ***\n");
	for(i=0; i<L_Nthread; i++)
	{
		nthreads = Nthread[i];
		T0 = clock();

        #pragma omp parallel for num_threads(nthreads) private(i,A,B) schedule(static)
		for(i=0; i<N; i++) {  B=rand(); A=2*B; }     

		T[i] = clock() - T0;
		printf("nthreads=%d, time=%.2e, speedup=%.2f\n", nthreads, T[i], T[0]/T[i]);
	}

// schedule: dynamic
    printf("\n*** Schedule: dynamic, 10 ***\n");
	for(i=0; i<L_Nthread; i++)
	{
		nthreads = Nthread[i];
		T0 = clock();

        #pragma omp parallel for num_threads(nthreads) private(i,A,B) schedule(dynamic,10)
		for(i=0; i<N; i++) {  B=rand(); A=2*B; }     

		T[i] = clock() - T0;
		printf("nthreads=%d, time=%.2e, speedup=%.2f\n", nthreads, T[i], T[0]/T[i]);
	}

// schedule: guided
    printf("\n*** Schedule: guided, 10 ***\n");
	for(i=0; i<L_Nthread; i++)
	{
		nthreads = Nthread[i];
		T0 = clock();

        #pragma omp parallel for num_threads(nthreads) private(i,A,B) schedule(guided,10)
		for(i=0; i<N; i++) {  B=rand(); A=2*B; }     

		T[i] = clock() - T0;
		printf("nthreads=%d, time=%.2e, speedup=%.2f\n", nthreads, T[i], T[0]/T[i]);
	}

    return 0;
}