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Unit 4.6.2 Summary

Subsubsection 4.6.2.1 The week in pictures

Subsubsection 4.6.2.2 OpenMP basics

OpenMP is a standardized API (Application Programming Interface) for creating multiple threads of execution from a single program. For our purposes, you need to know very little:

  • There is a header file to include in the file(s): 

    #include <omp.h>

  • Directives to the compiler (pragmas): 

    #pragma omp parallel 
#pragma omp parallel for

  • A library of routines that can, for example, be used to inquire about the execution environment: 

    omp_get_max_threads() 
omp_get_num_threads() 
omp_get_thread_num()

  • Environment parameters that can be set before executing the program: 

    export OMP_NUM_THREADS=4

    If you want to see what the value of this environment parameter is, execute 

    echo $OMP_NUM_THREADS

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