12. Seminar - Experiments with parallelization...
Use OpenMP to parallelize next example program computing multiplication of a vector by matrix.
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<omp.h>
#define abs(x) ((x)>0?(x):-(x))
void printUsage(const char *s){
printf( " *********************************** \
\n Usage: %s dimM dimN numOfThreads \
\n *********************************** \
\n Running with default parameters: %s 100 100 2\n\n",s,s);
}
void matrix_vector_mult_basic (double *A, double *x, double *y, int M, int N);
void matrix_vector_mult_parallel_first (double *A, double *x, double *y, int M, int N);
void matrix_vector_mult_parallel_second (double *A, double *x, double *y, int M, int N);
void matrix_vector_mult_parallel_third (double *A, double *x, double *y, int M, int N);
void matrix_vector_mult_parallel_forth (double *A, double *x, double *y, int M, int N);
void matrix_vector_mult_parallel_fifth (double *A, double *x, double *y, int M, int N);
void sleep(int sleep_time_ms);
int eq_test(double *a, double *b, int dim);
void show_vector(double *a, int dim);
int main(int argc, const char* argv[]){
int ii,jj, numOfProcs;
double tmp, sequential_time;
struct timespec start, stop;
double elapsed;
double *A, *x, *y,*res;
int M, N, numOfThreads; // Dimenze matic, pocet vlaken
if(argc < 4){ // Defaultni konfigurace
printUsage(argv[0]);
M=N=100;
numOfThreads=2;
}else{ // Konfigurace nactena z prikazoveho radku
M=atoi(argv[1]);
N=atoi(argv[2]);
numOfThreads = atoi(argv[3]);
}
/* Alokace pameti */
if((x=(double*)malloc(N*sizeof(double)))==NULL) { printf("Not enough memory..\n"); return 1; }
if((y=(double*)malloc(M*sizeof(double)))==NULL) { printf("Not enough memory..\n"); return 1; }
if((res=(double*)malloc(M*sizeof(double)))==NULL) { printf("Not enough memory..\n"); return 1; }
if((A=(double*)malloc(M*N*sizeof(double)))==NULL) { printf("Not enough memory..\n"); return 1; }
/* Initialization */
srand((unsigned)time(0));
for(ii=0;ii<N;ii++)
x[ii] = (double)rand()/(double)RAND_MAX;
for(ii=0;ii<M;ii++)
for(jj=0;jj<N;jj++)
A[ii+jj*M] = (double)rand()/(double)RAND_MAX;
/* */
numOfProcs = omp_get_num_procs();
omp_set_num_threads(numOfThreads);
printf("\n M=%d, N=%d, numOfThreads=%d\n\n",M,N,numOfThreads);
//------------------------------
clock_gettime(CLOCK_REALTIME, &start);
matrix_vector_mult_basic(A, x, res, M, N);
clock_gettime(CLOCK_REALTIME, &stop);
elapsed = (stop.tv_sec - start.tv_sec)*1000 + (double)(stop.tv_nsec - start.tv_nsec)/(double)1000000;
sequential_time = elapsed;
printf( " Execution without parallelization: %.2lf ms\n", elapsed);
//------------------------------
//------------------------------
clock_gettime(CLOCK_REALTIME, &start);
matrix_vector_mult_parallel_first(A, x, y, M, N);
clock_gettime(CLOCK_REALTIME, &stop);
elapsed = (stop.tv_sec - start.tv_sec)*1000 + (double)(stop.tv_nsec - start.tv_nsec)/(double)1000000;
printf( " Parallel execution: version 1: %.2lf ms, Speed-up: %.2lf, Efektivnost: %.2lf\n", elapsed, sequential_time/elapsed, sequential_time/elapsed/numOfProcs);
eq_test(res,y,M);
//------------------------------
//------------------------------
clock_gettime(CLOCK_REALTIME, &start);
matrix_vector_mult_parallel_second(A, x, y, M, N);
clock_gettime(CLOCK_REALTIME, &stop);
elapsed = (stop.tv_sec - start.tv_sec)*1000 + (double)(stop.tv_nsec - start.tv_nsec)/(double)1000000;
printf( " Parallel execution: version 2: %.2lf ms, Speed-up: %.2lf, Efektivnost: %.2lf\n", elapsed, sequential_time/elapsed, sequential_time/elapsed/numOfProcs);
eq_test(res,y,M);
//------------------------------
//------------------------------
clock_gettime(CLOCK_REALTIME, &start);
matrix_vector_mult_parallel_third(A, x, y, M, N);
clock_gettime(CLOCK_REALTIME, &stop);
elapsed = (stop.tv_sec - start.tv_sec)*1000 + (double)(stop.tv_nsec - start.tv_nsec)/(double)1000000;
printf( " Parallel execution: version 3: %.2lf ms, Speed-up: %.2lf, Efektivnost: %.2lf\n", elapsed, sequential_time/elapsed, sequential_time/elapsed/numOfProcs);
eq_test(res,y,M);
//------------------------------
//------------------------------
clock_gettime(CLOCK_REALTIME, &start);
matrix_vector_mult_parallel_forth(A, x, y, M, N);
clock_gettime(CLOCK_REALTIME, &stop);
elapsed = (stop.tv_sec - start.tv_sec)*1000 + (double)(stop.tv_nsec - start.tv_nsec)/(double)1000000;
printf( " Parallel execution: version 4: %.2lf ms, Speed-up: %.2lf, Efektivnost: %.2lf\n", elapsed, sequential_time/elapsed, sequential_time/elapsed/numOfProcs);
eq_test(res,y,M);
//------------------------------
printf( " \n");
/* Free allocated memory */
free(x);
free(y);
free(res);
free(A);
x = y = res = A = NULL;
return 0;
}
void matrix_vector_mult_basic(double *A, double *x, double *y, int M, int N)
{
/*
Function computes multiplication of matrix by vector: y = A*x
A - matrix of dimension MxN
x - vector of dimension N
y - vector of dimension M
*/
int ii, jj;
for(ii=0;ii<M;ii++){
y[ii] = 0.0;
for(jj=0;jj<N;jj++)
y[ii] += A[ii+jj*M]*x[jj];
}
}
/******************************************************************************/
void matrix_vector_mult_parallel_first(double *A, double *x, double *y, int M, int N)
{
}
/******************************************************************************/
void matrix_vector_mult_parallel_second(double *A, double *x, double *y, int M, int N)
{
}
/******************************************************************************/
void matrix_vector_mult_parallel_third(double *A, double *x, double *y, int M, int N)
{
}
/******************************************************************************/
void matrix_vector_mult_parallel_forth(double *A, double *x, double *y, int M, int N)
{
}
/******************************************************************************/
void matrix_vector_mult_parallel_fifth(double *A, double *x, double *y, int M, int N)
{
}
/******************************************************************************/
void sleep(int sleep_time_ms)
{
struct timespec start, stop;
double elapsed;
clock_gettime(CLOCK_REALTIME, &start);
do{
clock_gettime(CLOCK_REALTIME, &stop);
elapsed = (stop.tv_sec - start.tv_sec)*1000 + (double)(stop.tv_nsec - start.tv_nsec)/(double)1000000;
}while(elapsed<sleep_time_ms);
}
/******************************************************************************/
int eq_test(double *a, double *b, int dim)
{
int ii;
for(ii=0;ii<dim;ii++)
if(a[ii]!=b[ii]) { printf(" Vectors differ !!!\n\n"); return 0; }
return 1;
}
/******************************************************************************/
void show_vector(double *a, int dim)
{
int ii;
for(ii=0;ii<dim;ii++)
printf("%.2lf ",a[ii]);
printf("\n");
}
Example of achieved results:
