1 cw 2015, manchester, 04/20215 - coupling technology benchmarking in is-enes2 coupling technology...

1CW 2015, Manchester, 04/20215 - Coupling technology benchmarking in IS-ENES2

Coupling technology benchmarking in IS-ENES2

• IS-ENES2 WP10-T3 Evaluation of coupling strategies• Characteristics of coupling systems: tables & mindmaps• Priority coupling characteristics to benchmark• Definition of the coupled benchmark suite• Summary & conclusions

S. Valcke, CERFACS

Coupling Workshop 2015


IS-ENES2 WP10-T3 Evaluation of coupling strategies

CERFACS (9 pm), STFC (5 pm), UNIMAN (4 pm), MetO (9 pm), DKRZ (3 pm)

Objective: Define a suite of coupled benchmarks based on simplified components, which capture the essence of the coupling without the science complexity

1.Capture functional and performance characteristics of coupling system (CW2013)

2.Code a set of simplified components reproducing these characteristics

3.Implement the coupling between these components with OASIS and ESMF.

4.Run the benchmark suite on specific platforms.

5.Analyse results and present them to the community,

6.Undertake performance modelling to support the analysis of the benchmark

D10.3 Report on benchmark suite for evaluation of coupling strategies


Characteristics of coupling systems

Working groups at CW2013, Boulder:

•What are the scientific and technical requirements, including functional (e.g., data exchange, regridding, etc.) and non-functional (e.g., performance, flexibility, etc.) aspects, to build a geophysical coupled system from independent models?

•What are the qualities that should be assessed in a coupling technology benchmark and how should those qualities be measured?


•First series of mindmaps by US project Earth System Bridge reviewed during IS-ENES2 Exeter workshop (Feb 2014)



Coupling technologies

• architecture: basic design principles and other general characteristics• implementation: how the technology is implemented (library, parallelism, language,

etc. • utilities: all the utilities offered by the technology



Components

• characteristics of the components supported by the technology (language, parallelism, coupling data produced, …)



Composition

• coupling data transformation and transport, coupling modes supported



Deployment

Metadata

• how the components can be mapped on available computing resources

• as input for configuration, or produced, type of metadata



Priority coupling characteristics to benchmark

Type of the component grid Number of cores used for the components - up to O(104) Numbers of fields exchanged Frequency of exchange Size of the coupling fields:

“coarse” global grid of ~200 km resolution “high-resolution” global grid of 20-50 km self-generated latitude-longitude grids for very high-resolution

tests

(Ease of use: code intrusion, development time, techniques for overcoming specific issues)


Definition of the coupled benchmark suite

Pre-coded stand-alone components running on different grids

• Fortran subroutine(s) with no physics/dynamics but real coupling characteristics

• MPI parallel

• Coupling fields as IN/OUT arguments, arrays in shared modules, local data

• Ways to check correctness & completion

• Use specific grids– latlon: latitude-longitude, arbitrary resolution (STFC/UNIMAN)

– stretched: stretched & rotated, logically rectangular, e.g. ORCA (CERFACS)

– icosa: quasi-uniform icosahedral, e.g. NICAM (CERFACS)

– cubedsphere: quasi-uniform cubed sphere (MetO/UNIMAN)

Coupling specifications:

• Coupling fields in both directions every tstep

• Concurrent & sequential execution

• Timings: init; 1st tstep; mean, max, min over 99 tsteps

A list of test cases to be implemented


Definition of the coupled benchmark suite

• icosa - icosa :– OASIS3-MCT : CERFACS– OpenPALM : CERFACS– ESMF : CERFACS

• stretched –icosa– OASIS3-MCT : CERFACS– OpenPALM : CERFACS

• stretched – Gauss reduced– OASIS3-MCT : CERFACS

A list of test cases to be implemented • latlon - latlon with same decomposition on both sides:

– OASIS3-MCT : CERFACS– OpenPALM : CERFACS– ESMF : STFC/UNIMAN– MCT : STFC/UNIMAN

• latlon - latlon with different decompositions on both sides:– OASIS3-MCT : CERFACS– OpenPALM : CERFACS– ESMF : STFC/UNIMAN – MCT : STFC/UNIMAN

• stretched - latlon:– OASIS3-MCT : CERFACS– OpenPALM : CERFACS– ESMF : MetOffice

• cubedsphere (with finite differences) - latlon : – OASIS3-MCT : MetO– ESMF : MetO

• cubedsphere (with finite elements) - latlon:– OASIS3-MCT : MetO– ESMF : MetO


Summary & conclusion Functional and non-functional characteristics of coupling systems captured in comprehensive mindmaps

International collaboration

Used as a basis to define a questionnaire to characterize existing technologies, see Rocky Dunlap’s talk

Priority characteristics for IS-ENES2 benchmark identified Coupling benchmark characteristics established:

• stand-alone components• coupling specifications• test-cases to be implemented

Work has started:• Icosa & streched grid standalone components coding at CERFACS• On going- work at the MetOffie (see Mike Hobson’s talk)

Benchmark tests planned 2015-16 for deliverable 11/2016 Benchmarks to be extended in ESIWACE, the Centre of Excellence in Simulation of Weather and Climate in Europe, if funded


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1 cw 2015, manchester, 04/20215 - coupling technology benchmarking in is-enes2 coupling technology...

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