Agenda Notes Monday August 20th 2018 11:00 AM

MPAS-Developer Telecon:

Date: 20 August 2018
Time: 11:00 MDT / 19:00 CET

Call-in number: 1-866-740-1260
Access Code: 4978161

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Agenda Topics:

1. Framework modifications:
   • Open framework PRs (open-development repo)
2. Completion of repo reorganization:
   • Here is the initial discussion for repo organization: https://docs.google.com/document/d/1MGYIydK9ufuqfUySkbxcusPSPL9eGUphbot9-GP8DjE/edit?usp=sharing
   • I just revised with the most current information: https://docs.google.com/document/d/1h5QFXcDtoX-pUSlYfJkhpb1WAF6otGbP5SZXsWInITs/edit?usp=sharing
3. C interoperability
4. How to handle deprecation of GitHub Services? When committing to a repository, we now get e-mails that conclude with the following:

      **NOTE:** This service has been marked for deprecation: https://developer.github.com/changes/2018-04-25-github-services-deprecation/

      Functionality will be removed from GitHub.com on January 31st, 2019.

Notes from the previous meeting:

Monday 21 May 2018 @ 11:00 MDT

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Notes:

C interoperability

Attendees

• @mgduda
• @mark-petersen
• @matthewhoffman
• @pwolfram

@mgduda's view on path forward (via experience with C++ OOPS data assimilation)

• C-compatible pointers: @mgduda to figure out if RKIND can be used to spec C floats or doubles
• Contiguous memory: Not clear if multidimensional arrays will be contiguous (in general), although heuristically appears to be true in practice. Enforce with contiguous at root level keyword to 1) multi-dimensional array pointer to C pointer will yield contiguous block of memory, 2) pointers to query via pools will be potentially more efficient
• Removal of block loops: consider removal of all block loops from MPAS
• Can call C-code from MPAS already

Questions, Concerns, thoughts:

• @mark-petersen: contiguous helps with vectorization (e.g., verbose compile requires contiguous)
• @mark-petersen, @matthewhoffman: block structures are still to be used by @akturner; @mgduda-- huge amount of work removing block loops (but just to improve simplicity of framework code)
• @mark-petersen: @philipwjones to consider rewriting framework, consider coordination of design with @mgduda in design document process with performance needs
• @mark-petersen: @mgduda, what would be your top 5 framework improvements and should they all be done together?
• @mgduda: OOPS C++ class with data model working mostly on bare arrays from MPAS (but halo-exchanges will require a Fortran code call)
• @matthewhoffman willing to provide high-level initial advice based on work with Albany, Trilinos in MPAS