[Wrf-users] Benchmarking problems
andrew.porter at stfc.ac.uk
Tue Mar 15 03:28:21 MDT 2011
> numtiles = 1,
> nproc_x = 3,
> nproc_y = 2,
> num_metgrid_levels = 40,
> I set OMP_NUM_THREADS to 6 in my run script that calls wrf.exe.
> And yet, when I look in the resulting wrf.out file I see:
> WRF NUMBER OF TILES FROM OMP_GET_MAX_THREADS = 6
> WRF NUMBER OF TILES = 6
> Hey! I told you to use 1 tile and split it 3 by 2!
I think nproc_x and nproc_y only applies to MPI processes. By telling it
to use only 1 tile I think you'll end up with 5 threads not doing
anything! You can leave ntiles out to have it set to OMP_NUM_THREADS by
default or you can set it > OMP_NUM_THREADS to see whether that fits
things into cache more successfully.
Dr. Andrew Porter
Advanced Research Computing Group
Computational Science and Engineering Dept.
STFC Daresbury Laboratory
Tel. : +44 (0)1925 603607
email: andrew.porter at stfc.ac.uk
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