Lfric2lfric no multi partition

[ukmo-juan-castillo]

PR Summary

Sci/Tech Reviewer:
Code Reviewer:

When reading a multigrid mesh file, by default all meshes this file contains are partitioned. It would be desirable for lfric2lfric to just partition, and make checks on mesh dimensions against CPU number, on the source and destination meshes. This functionality is already present in lfric_core via the any_maps parameter of the get_partition subroutine of the panel_decomposition_type object. On the other hand, this object subroutine is not called directly in most applications, so this functionality should be made more accessible.

The solution proposed here is the creation of a logical variable in the global_mesh object, with set/get subroutines, indicating if the multiple meshes have to be partitioned. This is similar to what is presently done, where the global_mesh variable ntarget_meshes is used to find if there are multiple meshes.

Other solutions have been considered, for example:
. Extracting the any_maps parameter of the subroutine get_partition contained in the object panel_decomposition_type in successive subroutine calls until it can be used in the calling subroutine create_local_mesh. This would imply large changes in both lfric_core and lfric_apps
. Doing the same as before, but using optional subroutine parameters. Although this would minimise the number of changes in lfric_core and lfric_apps, the addition of new optional subroutine parameters is discouraged.
. Make changes in lfric2lfric to use the existing any_maps parameter of the subroutine get_partition. Lfric_core would not change, but this would imply duplicating large pieces of lfric_core code in lfric2lfric.

Any other suggestion by the reviewer would be considered and tested if necessary.

This PR can not be properly tested until completion of PR #201

• linked Decide if partitioning all meshes in a multigrid mesh file lfric_core#289

• blocked-by Lfric2lfric multi cpu #201

• closes lfric2lfric: do not partition multigrid meshes #290

• fixes lfric2lfric: do not partition multigrid meshes #290

Code Quality Checklist

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid understanding and enhance the readability of the code
• My changes generate no new warnings
• All automated checks in the CI pipeline have completed successfully

Testing

• I have tested this change locally, using the LFRic Apps rose-stem suite
• If any tests fail (rose-stem or CI) the reason is understood and acceptable (e.g. kgo changes)
• I have added tests to cover new functionality as appropriate (e.g. system tests, unit tests, etc.)
• Any new tests have been assigned an appropriate amount of compute resource and have been allocated to an appropriate testing group (i.e. the developer tests are for jobs which use a small amount of compute resource and complete in a matter of minutes)

trac.log

Test Suite Results - lfric_apps - lfric2lfric_no_multi_partition/run1

Suite Information

Item	Value
Suite Name	lfric2lfric_no_multi_partition/run1
Suite User	juan.m.castillo
Workflow Start	2026-02-25T11:09:50
Groups Run	all

Dependency	Reference	Main Like
casim	MetOffice/casim@2025.12.1	True
jules	MetOffice/jules@69aaf4d	True
lfric_apps	ukmo-juan-castillo/lfric_apps@test_lfric2lfric_multi_CPU	False
lfric_core	ukmo-juan-castillo/lfric_core@3a3df7d	True
moci	MetOffice/moci@2025.12.1	True
SimSys_Scripts	MetOffice/SimSys_Scripts@2025.12.1	True
socrates	MetOffice/socrates@2025.12.1	True
socrates-spectral	MetOffice/socrates-spectral@2025.12.1	True
ukca	MetOffice/ukca@2025.12.1	True

Task Information

✅ succeeded tasks - 1515

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• Some of the content of this change has been produced with the assistance of Generative AI tool name (e.g., Met Office Github Copilot Enterprise, Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the Simulation Systems AI policy (including attribution labels)

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Sci/Tech Review

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• Sufficient testing has been completed

(Please alert the code reviewer via a tag when you have approved the SR)

Code Review

• All dependencies have been resolved
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