User Tools

Site Tools


faq:mpi_vs_openmp

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

faq:mpi_vs_openmp [2014/02/25 10:20] (current)
oschuett created
Line 1: Line 1:
 +====== Should I use MPI or OpenMP or both? ======
 +
 +The entire CP2K code is MPI parallelized. Some additional loops are also OpenMP parallelized.
 +You should therefore first take advantage of the MPI parallelization.
 +However, running one MPI-rank per CPU-core will probably lead to memory shortage.
 +
 +At this point, OpenMP threads can be used to utilized all CPU-cores without the large memory-footprint of a MPI-process.
 +
 +The optimal ratio between MPI-ranks and OpenMP-threads depends on the kind of simulation you run.
 +Do your own benchmarks! A ratio of two threads per rank is usually a good point to start.
  
faq/mpi_vs_openmp.txt ยท Last modified: 2014/02/25 10:20 by oschuett