Running tiled WRF

The second version of WRF (and WRF-CHEM) included in the image enables running multi-tiled WRF.  This can be advantageous as the chiplet used by AMD EPYC2 and EPYC3 processors have a shared L3 cache across several cores. By running jobs using a hybrid scheme (MPI + OpenMP), some cases will improve performance. However, this is not certain for every simulation and we recommend performing some tests before deciding which scheme is better for that particular case.

To run a case in for example a D96as_v4 VM, the command sequence would be:

  • $ cd /home/wrfuser/TILED/WRF-4.3.2/test/em_real
  • $ ./real.exe
  • $ export OMP_NUM_THREADS=4
  • $ mpirun -np 12 ./wrf.exe

This assumes that the namelist.input and meteorological files are located at /home/wrfuser/TILED/WRF-4.3.2/test/em_real (and that the username for the VM is wrfuser). Here, namelist.input should include the line numtiles = 4 and the app will use 12 MPI ranks with each one of them running on 4 cores (the app will automatically pick up the optimal distribution across the 48 cores).