TP-openmp/BE_OpenMP_2014/synchronizations/main.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "omp.h"
#include "aux.h"
#define NIT 1000000
#define NE 10000

void sequential(int *data);
void parallel_critical(int *data);
void parallel_atomic(int *data);
void parallel_locks(int *data);

int main(int argc, char **argv)
{
  int n, i, j, k, nth, thn, cnt;
  long t_start, t_end, save;
  double s, z, x, y, nx, ny, nz, mz;
  int data[NE];

  /* Initialize data */
  for (i = 0; i < NE; i++)
    data[i] = 0;

  t_start = usecs();
  sequential(data);
  t_end = usecs();

  for (cnt = 0, i = 0; i < NE; i++)
  {
    cnt += data[i];
  }
  printf("Sequential   time : %8.2f msec.", ((double)t_end - t_start) / 1000.0);
  printf("       -- result: %4d\n", cnt);

  /***********************************************************************/
  /***********************************************************************/
  /***********************************************************************/

  for (i = 0; i < NE; i++)
    data[i] = 0;

  t_start = usecs();
  parallel_critical(data);
  t_end = usecs();

  for (cnt = 0, i = 0; i < NE; i++)
  {
    cnt += data[i];
  }
  printf("Critical     time : %8.2f msec.", ((double)t_end - t_start) / 1000.0);
  printf("       -- result: %4d\n", cnt);

  /***********************************************************************/
  /***********************************************************************/
  /***********************************************************************/

  for (i = 0; i < NE; i++)
    data[i] = 0;

  t_start = usecs();
  parallel_atomic(data);
  t_end = usecs();

  for (cnt = 0, i = 0; i < NE; i++)
  {
    cnt += data[i];
  }
  printf("Atomic       time : %8.2f msec.", ((double)t_end - t_start) / 1000.0);
  printf("       -- result: %4d\n", cnt);

  /***********************************************************************/
  /***********************************************************************/
  /***********************************************************************/

  for (i = 0; i < NE; i++)
  {
    data[i] = 0;
  }

  t_start = usecs();
  parallel_locks(data);
  t_end = usecs();

  for (cnt = 0, i = 0; i < NE; i++)
  {
    cnt += data[i];
  }
  printf("Locks        time : %8.2f msec.", ((double)t_end - t_start) / 1000.0);
  printf("       -- result: %4d\n", cnt);

  return 0;
}

void sequential(int *data)
{
  int i, j;

  for (i = 0; i < NIT; i++)
  {
    j = rand() % NE;
    data[j] += func();
  }
}

void parallel_critical(int *data)
{
  int i, j;

#pragma omp parallel

#pragma omp for
  for (i = 0; i < NIT; i++)
  {
    j = rand() % NE;
#pragma omp critical
    data[j] += func();
  }
}

void parallel_atomic(int *data)
{
  int i, j;

#pragma omp parallel

#pragma omp for
  for (i = 0; i < NIT; i++)
  {
    j = rand() % NE;
#pragma omp atomic update
    data[j] += func();
  }
}

void parallel_locks(int *data)
{
  int i, j;
  omp_lock_t *lock = malloc(sizeof(omp_lock_t));

  omp_init_lock(lock);

#pragma omp parallel shared(lock)

#pragma omp for
  for (i = 0; i < NIT; i++)
  {
    j = rand() % NE;
    omp_set_lock(lock);
    data[j] += func();
    omp_unset_lock(lock);
  }

#pragma omp single
  free(lock);
}