c - OpenMP giving inconsistent order of data -


i wrote code in c using openmp, first 4 results when compiling in different order , run time shows value other 0 half of time. missing something? here code:

#include <stdio.h> #include <stdlib.h> #include <omp.h>  void test(int *ptr0, int *ptr1, int n) {     int sum=0, i;     int id=omp_get_thread_num();      for(i=0;i<16;i++){         sum+=prt0[i]*ptr1[i];     }      printf("sum = %d thread %d\n",sum,id); }  int main() {     int m=64, n=16, a, b;      int** array0=calloc(m, sizeof(int*));     for(a=0;a<m;a++){         array0[a]=calloc(n, sizeof(int));     }      int** array1=calloc(m, sizeof(int*));     for(b=0;b<m;b++){         array1[b]=calloc(n, sizeof(int));     }      for(i=0;i<16;i++);{         array0[i][n/2]=i;         array1[i][n/2]=i;     }      #pragma omp parallel schedule(dynamic)         for(i=0;i<n;i++){             test(array0[i],array1[i],n);         }      double start_time, run_time;     start_time=omp_get_wtime();     run_time=omp_get_wtime()-start_time;     printf("total run time = %.5g seconds\n", run_time);  }

the results (with different variations of first 4 lines):

sum = 0 thread 3 sum = 1 thread 1 sum = 4 thread 2 sum = 9 thread 3 sum = 16 thread 0 sum = 25 thread 1 sum = 36 thread 2 sum = 49 thread 3 sum = 64 thread 0 sum = 81 thread 1 sum = 100 thread 2 sum = 121 thread 3 sum = 144 thread 0 sum = 169 thread 1 sum = 196 thread 2 sum = 225 thread 3 total run time = 3.95e-07 seconds

any suggestions on how can make results consistent sums being 0, 1, 4, 9, etc. , run time isn't 0 seconds?

why expect long duration requesting current start & end time in row? didn't want measure something? guess real target start time before loop starts , end time after tests done.

the order of outputs can't control because out of control how fast threads work. put results in additional array , print contents in main thread.


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