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howto:wrf [2020/06/30 09:08]
ccrosby [Running ARW / WRF at the CHPC]
howto:wrf [2020/06/30 09:09] (current)
ccrosby [OpenMP]
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 ==== OpenMP ==== ==== OpenMP ====
-WRF-4.0 ​and WRF-4.1.1 have been installed with support for OpenMP. It is therefore possible to run using the same number of cores in total, but fewer MPI processes. ​ By default, the environment variable **OMP_NUM_THREADS** is set to 1 in the setWRF script. ​ Testing on Lengau has confirmed that there are substantial performance benefits to be obtained from using OpenMP. ​ Benchmark results are given below, but it appears to be close to optimal to use 6 MPI ranks per node, with 4 OpenMP threads per MPI rank. If you want to experiment with OpenMP, set this variable in your job script ** after ** sourcing the setWRF script. Although the WRF-4 / gcc-8.3.0 / mpich-3.3 installation also supports OpenMP, performance testing indicates that this version does not benefit from using OpenMP. ​ The version compiled with the PGI compiler is competitive with the Intel version when using MPI only, but also does not benefit from adding OpenMP.+WRF-4.0WRF-4.1.1 ​and WRF-4.2 ​have been installed with support for OpenMP. It is therefore possible to run using the same number of cores in total, but fewer MPI processes. ​ By default, the environment variable **OMP_NUM_THREADS** is set to 1 in the setWRF script. ​ Testing on Lengau has confirmed that there are substantial performance benefits to be obtained from using OpenMP. ​ Benchmark results are given below, but it appears to be close to optimal to use 6 MPI ranks per node, with 4 OpenMP threads per MPI rank. If you want to experiment with OpenMP, set this variable in your job script ** after ** sourcing the setWRF script. Although the WRF-4 / gcc-8.3.0 / mpich-3.3 installation also supports OpenMP, performance testing indicates that this version does not benefit from using OpenMP. ​ The version compiled with the PGI compiler is competitive with the Intel version when using MPI only, but also does not benefit from adding OpenMP.
  
 ==== WRF, Parallel NetCDF and I/O Quilting ==== ==== WRF, Parallel NetCDF and I/O Quilting ====
/var/www/wiki/data/pages/howto/wrf.txt · Last modified: 2020/06/30 09:09 by ccrosby