Pre-compute mappings?

[aekiss]

For performance we might want to pre-compute mappings rather than auto-generating them at runtime (see ACCESS-NRI/access-om3-configs#5) - but only if auto-generating consumes a lot of walltime.

Unclear whether this is currently possible with CDEPS; might require code changes.

[anton-seaice]

I think we should investigate this before we start doing long runs / cmip7 runs. If they are only getting calculated once after a restart and then stored for the rest of the run that might be ok, but if they are recalculated for every interpolation / regrid then we should definately pre-compute them.

[micaeljtoliveira]

Another important detail is the parallelisation of the mappings computation. Is it serial code? Parallel? If parallel, what is the scalability?

[aekiss]

Online remapping weight generation is parallel, according to slide 5 of @mvertens CW2023 talk.

[mvertens]

@micaeljtoliveira - that is correct. Its totally parallel.

[mvertens]

@micaeljtoliveira - all IO in CMEPS is parallel as well.

[aekiss]

@micaeljtoliveira do your scaling tools allow checking how well the weight generation parallelises?

[micaeljtoliveira]

do your scaling tools allow checking how well the weight generation parallelises?

Yes, we might just need to add some profiling regions.