57954 Slajd7 (27)

Implicit Threading

np. Open MP, Intel Threading Builaing Blocks (TBB)

static long num_rects = lOOOOO;

int main(int argc, char* argv[])    {

double mid, height, width, sum = 0.0/ int i/

double area/

width = 1.0/(double) num_rects;

#pragma omp parallel for private(mid, height) reduction(+: sum) for (i = 0/ i < num_rects/ i++)    {

mid = (i + 0.5) * width/ height = 4.0/(1.0 + mid * mid)/ sum += height/

}

area = width * sum/

printf("Computed pi = %f\n", area)/ return 0/

}

Zmienna środowiskowa ompjntjm threads określa liczbę wątków.

T2-2 - Modele obliczeń rozproszonych Marek Nowak 7