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Input/output (IO) can also have a big impact on model performance. So as to not confuse I/O performance with model performance, the usual steps are:
- Get a working PIO settings, so that the model will not crash while reading input settings. Often the default settings will not work, especialy on vary large or very small processor counts.
- Disable history output and restart files for all components. Then you can use short (5-10 days) simulations to determine an optional processor layout. Otherwise, short simulations will be dominated by I/O costs and will give misleading performance numbers. Input and initialization times are not included in SYPD computations.
- Once you have a reasonable processor layout without I/O, use 1 month simulations to test PIO settings.
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