Performance Optimisation and Productivity
A Centre of Excellence in HPC
OpenMP regular parallelization of nested loop
Version's name: OpenMP regular parallelization of nested loop ; a version of the OMP Collapse program.Repository: [home] and version downloads: [.zip] [.tar.gz] [.tar.bz2] [.tar]
Patterns and behaviours: Recommended best-practices:
- Collapsing OpenMP parallel loops - Available version(s): OpenMP nested loop collapse ·
This is a simple OpenMP implementation parallelizing the outer loop of multiple nested loops.
The following pseudo-code shows the structure of the nested loops. An outer and two nested loops
with different sizes (Nk, Nj, Ni) compute work on a three-dimensional array.
DO K = 1, Nk
DO J = 1, Nj
DO I = 1, Ni
!! work to do
END DO
END DO
END DO
The loop iterations can be divided among threads by using the following one-level OpenMP parallelization construct on the outer loop:
!$OMP PARALLEL DO DEFAULT(NONE) SHARED(...)
DO K = 1, Nk
DO J = 1, Nj
DO I = 1, Ni
!! work to do
END DO
END DO
END DO
!$OMP END PARALLEL DO
