Very slow. How to move the threads creation to main_?












0












$begingroup$


Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.



double funcPar()
{
double sum = { 0, 0, 0, 0 };
#pragma omp parallel
{
#pragma omp for
for (int i = 0; i < 4; i++) //loop body should be parallel (multy-threaded)
{
auto a = (double)i;
sum[i] += sin(a)*cos(a); // real code is more complicated and works much longer
}
}//omp parallel
return sum[0] + sum[1] + sum[2] + sum[3];
}
double funcSerial() //function should remain serial (single-threaded)
{
int K = 5000;
double sum = 0.0;
for (int k = 0; k < K; k++)
{
sum += funcPar();
}
return sum;
}
void main_() // //function body should remain serial (single-threaded)
{
int J = 1000;
double sum = 0.0;
for (int j = 0; j < J; j++)
{
sum += funcSerial();
}
printf("nn sum = %f n", sum);
}


Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.










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$endgroup$

















    0












    $begingroup$


    Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.



    double funcPar()
    {
    double sum = { 0, 0, 0, 0 };
    #pragma omp parallel
    {
    #pragma omp for
    for (int i = 0; i < 4; i++) //loop body should be parallel (multy-threaded)
    {
    auto a = (double)i;
    sum[i] += sin(a)*cos(a); // real code is more complicated and works much longer
    }
    }//omp parallel
    return sum[0] + sum[1] + sum[2] + sum[3];
    }
    double funcSerial() //function should remain serial (single-threaded)
    {
    int K = 5000;
    double sum = 0.0;
    for (int k = 0; k < K; k++)
    {
    sum += funcPar();
    }
    return sum;
    }
    void main_() // //function body should remain serial (single-threaded)
    {
    int J = 1000;
    double sum = 0.0;
    for (int j = 0; j < J; j++)
    {
    sum += funcSerial();
    }
    printf("nn sum = %f n", sum);
    }


    Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.










    share|improve this question







    New contributor




    Джон Доу is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$















      0












      0








      0





      $begingroup$


      Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.



      double funcPar()
      {
      double sum = { 0, 0, 0, 0 };
      #pragma omp parallel
      {
      #pragma omp for
      for (int i = 0; i < 4; i++) //loop body should be parallel (multy-threaded)
      {
      auto a = (double)i;
      sum[i] += sin(a)*cos(a); // real code is more complicated and works much longer
      }
      }//omp parallel
      return sum[0] + sum[1] + sum[2] + sum[3];
      }
      double funcSerial() //function should remain serial (single-threaded)
      {
      int K = 5000;
      double sum = 0.0;
      for (int k = 0; k < K; k++)
      {
      sum += funcPar();
      }
      return sum;
      }
      void main_() // //function body should remain serial (single-threaded)
      {
      int J = 1000;
      double sum = 0.0;
      for (int j = 0; j < J; j++)
      {
      sum += funcSerial();
      }
      printf("nn sum = %f n", sum);
      }


      Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.










      share|improve this question







      New contributor




      Джон Доу is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.



      double funcPar()
      {
      double sum = { 0, 0, 0, 0 };
      #pragma omp parallel
      {
      #pragma omp for
      for (int i = 0; i < 4; i++) //loop body should be parallel (multy-threaded)
      {
      auto a = (double)i;
      sum[i] += sin(a)*cos(a); // real code is more complicated and works much longer
      }
      }//omp parallel
      return sum[0] + sum[1] + sum[2] + sum[3];
      }
      double funcSerial() //function should remain serial (single-threaded)
      {
      int K = 5000;
      double sum = 0.0;
      for (int k = 0; k < K; k++)
      {
      sum += funcPar();
      }
      return sum;
      }
      void main_() // //function body should remain serial (single-threaded)
      {
      int J = 1000;
      double sum = 0.0;
      for (int j = 0; j < J; j++)
      {
      sum += funcSerial();
      }
      printf("nn sum = %f n", sum);
      }


      Fully workable code. Very slow. How to move the threads creation to main_ ? Do not break the structure of the code.







      c++ openmp






      share|improve this question







      New contributor




      Джон Доу is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question







      New contributor




      Джон Доу is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question






      New contributor




      Джон Доу is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      asked 36 mins ago









      Джон ДоуДжон Доу

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      Джон Доу is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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