estimating memory requirements based on grid size
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wstockhausen
- Posts: 1
- Joined: Tue Jan 25, 2005 10:38 pm
- Location: NOAA Fisheries
estimating memory requirements based on grid size
As a new user to ROMS, I am wondering if any formulas or rules of thumb have been developed for estimating overall memory requirements based on grid size? (I noted that the discussion of benchmarks in one of the other forums included information on processor speeds and configurations, but not on system RAM)
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m.hadfield
- Posts: 521
- Joined: Tue Jul 01, 2003 4:12 am
- Location: NIWA
It depends on the model configuration, obviously, but for a hydrodynamics-only simulation with not too many extra options enabled you can expect to require about 40-50 times the memory occupied by a single, 3D, REAL*8 array.
When I look at the ROMS 2.1 code, I can account easily for about 40% of this. I'm not sure where the rest goes.
When I look at the ROMS 2.1 code, I can account easily for about 40% of this. I'm not sure where the rest goes.
BENCHMARK1 (512x64x30) uses over 256 MB while BENCHMARK3 (2048x256x30) uses over 5 GB of memory. This is the serial code. For the MPI parallel code, I get vastly different memory requirements on the Cray X1 and the IBM, the Cray needing surprisingly huge amounts of memory, with the amount depending on the number of partitions.