Add option to auto-compute an IO LAYOUT when auto masking is on#342
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When Auto Masking is enabled, the LAYOUT is unknown a priori, so it's not possible to predetermine a compatible IO_LAYOUT. This commit introduces an option to set a target number of IO PEs (TARGET_IO_PES), to be used as a reference for the auto masking routine to come up with an IO_LAYOUT compatible with LAYOUT on the fly. If original TARGET_IO_PES is not achievable without having to sacrifice too much land masking, IO PEs is decremented until a feasible combination of LAYOUT and IO_LAYOUT is found.
This was referenced Mar 4, 2025
jedwards4b
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Mar 5, 2025
mnlevy1981
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Mar 17, 2025
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Details of my testing in ESCOMP/FMS#5 (review)
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This is one of three PRs to enable automated parallel IO in MOM6 within CESM by making use of the existing parallel IO implementation that comes with FMS. These series of PRs (1) enable FMS parallel IO, (2) make sure the IO PE Layout is compatible with auto-land block elimination (i.e., masking), and (3) that partitioned files are automatically merged after a run is completed.
When auto-masking (land-block elimination) is enabled, the compute PE
LAYOUTis unknown a priori, so it's not possible to predetermine an IO_LAYOUT compatible withLAYOUT. This PR introduces an option to set a target number of IO PEs (TARGET_IO_PES), to be used as a reference for the auto-masking routine to determine an IO_LAYOUT compatible with LAYOUT on-the-fly. If original TARGET_IO_PES is not achievable without having to sacrifice too much auto land masking, then the number of IO PEs is decremented until a feasible combination of LAYOUT and IO_LAYOUT is found.testing: aux_mom.derecho
status: b4b, except for masking in static files due to changing compute layout.
Performance: varies depending on the resolution, pe count and IO layout, from no enhancement or degradation to more than 50% enhancement.
This PR should be evaluated in conjunction with:
ESCOMP/FMS#5
ESCOMP/MOM_interface#235