HPC-3-use-openmp(shared-memory-method)

Tue, 16 Apr 2024 00:05:14 -0400

Introduction to HPC, shared memory parallel using openmp

The relationship with L1-L3 cache. The L3 cache is shared, but every core have its own L1-2 cache.

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#include "omp.h"

Before using it, we need to define how many threads we want to use:

In Unix system:

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export OMP_NUM_THREADS=4

The instruction:

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#pragma omp parallel

If we put this macro before one line of code or one block, the line or block will be executed $OMP_NUM_TRHREADS times.