RMK001: loop nesting that might benefit from hybrid parallelization using multithreading and SIMD

This remark is part of the open catalog of best practice rules for performance that is automatically detected and reported by Codee.

Issue

Use multi-threading and SIMD hybrid parallelization to maximize the parallel performance of the nested loop.

Relevance

Certain nested loops may benefit from using a hybrid parallelization approach where the outer loop is parallelized using multi-threading while using vectorization for the inner loop. In this way, the use of modern hardware is maximized by using as many CPU cores as possible through multi-threading and at the same time using the vectorization hardware available in each core.

Actions

Parallelize the outer loop using multi-threading and the inner loop using vectorization. You can do so for OpenMP by invoking:

pwdirectives --omp multi+simd <foo.c:5> -o foo-hybrid.c