Recommended build configuration

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| by mrd599@nci.org.au

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Page to track changes to the UM build configuration in the coupled model.

Should we set up a branch that merges all these?

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Issue migrated from trac:323 at 2024-01-31 18:29:49 +1100

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@martin.dix@anu.edu.au edited the issue description

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@martin.dix@anu.edu.au commented

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um_sources=
branches/dev/mohitdalvi/vn10.6_ageair_new_reset_method@30614 
branches/dev/alistairsellar/vn10.6_ukca_emiss_improve@30463 
branches/dev/martindix/vn10.6_access_cm2@40051 
branches/dev/martindix/vn10.6_gregorian_climate_means@38760 
branches/dev/marcstringer/vn10.6_fix_OpenMP_nice_use@31443 
branches/dev/paulselwood/vn10.6_rm_vectlib_hooks@31287

https://code.metoffice.gov.uk/trac/um/log/main/branches/dev/martindix/vn10.6_access_cm2 Main branch for ACCESS-CM2 coupling code. Recent fixes for rdump/sdump

https://code.metoffice.gov.uk/trac/um/log/main/branches/dev/mohitdalvi/vn10.6_ageair_new_reset_method?rev=30614

https://code.metoffice.gov.uk/trac/um/log/main/branches/dev/alistairsellar/vn10.6_ukca_emiss_improve?rev=30463 Supports use of flexible calendar in UKCA emissions

https://code.metoffice.gov.uk/trac/um/log/main/branches/dev/martindix/vn10.6_gregorian_climate_means 10-15% time saving through avoiding unnecessary gather to PE0 for partial mean files

https://code.metoffice.gov.uk/trac/um/log/main/dev/marcstringer/vn10.6_fix_OpenMP_nice_use?rev=31443 Fixes OpenMP bug in loop over ice categories. Required when using more than 1 thread.

https://code.metoffice.gov.uk/trac/um/log/main/branches/dev/paulselwood/vn10.6_rm_vectlib_hooks?rev=31287 Reduces DRHOOK overhead. Very little impact on runs w/o DRHOOK

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rb4844 commented

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Merging would be good.

Also, Arnold is looking at a new suite which combines some other recent changes including openmpi/1.10.2 and reduced model output.

See also a new ticket regarding MOM compiler flags.

So, maybe establish a new 'reference' suite we can all work from.

And if this could have the CICE build in the right place.

My 'wish' list would also include removing many/all of the extra compilers etc that we don't use, and perhaps standardise some of the naming so its a bit clearer as to what some bits are for e.g. name the CICE build/compiler appropriately, perhaps with reference to the version number e.g. MOM5_1, CICE5 etc, and its for CM2, and its own version number?

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@martin.dix@anu.edu.au commented

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Experiments with UM compiler options. Each case is 10 x 1 day runs on the broadwell nodes with a 14x20 decomposition, intel-fc/17.0.1.132. No STASH output and no dump written.

Times are for atm_step as reported by the internal timer. This excludes the model startup and so should be more representative of long runs.

Case	Best (s)	Mean (s)	Notes
safe: -O2 -fp-model precise	89.34	90.99
high: -xavx -O3 -fp-model precise	91.14	93.82
-xavx2 -O2 -fp-model precise	90.48	93.57	Not reproducible across decompositions
-O2 -fp-model precise -align array64byte	88.07	90.88
-O2 -fp-model precise-align array64byte -fast-transcendentals -fimf-precision=high	86.70	88.36	Not reproducible across decompositions
-align array64byte -O3 -fp-model fast.	82.02	85.29	Not reproducible across decompositions

If we want to maintain reproducibility across different decompositions then the only option that helps is -align array64byte.

It's possible that -xavx2 would help on some routines.

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@martin.dix@anu.edu.au changed _comment0 which not transferred by tractive

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@martin.dix@anu.edu.au commented

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branches/dev/martindix/vn10.6_gregorian_climate_means@42947 fixes a bug when using >= 1000 MPI proceses in the UM.

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@martin.dix@anu.edu.au changed status from new to assigned

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@martin.dix@anu.edu.au set owner to mrd599