1 CW 2015, Manchester, 04/ 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

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

3 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 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?

4 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 First series of mindmaps by US project Earth System Bridge reviewed during IS-ENES2 Exeter workshop (Feb 2014) Characteristics of coupling systems

5 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 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 Characteristics of coupling systems

6 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 Components characteristics of the components supported by the technology (language, parallelism, coupling data produced, …) Characteristics of coupling systems

7 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 Composition coupling data transformation and transport, coupling modes supported Characteristics of coupling systems

8 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 Deployment Metadata how the components can be mapped on available computing resources as input for configuration, or produced, type of metadata Characteristics of coupling systems

9 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 Priority coupling characteristics to benchmark  Type of the component grid  Number of cores used for the components - up to O(10 4 )  Numbers of fields exchanged  Frequency of exchange  Size of the coupling fields:  “coarse” global grid of ~200 km resolution  “high-resolution” global grid of km  self-generated latitude-longitude grids for very high-resolution tests  (Ease of use: code intrusion, development time, techniques for overcoming specific issues)

10 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 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; 1 st tstep; mean, max, min over 99 tsteps  A list of test cases to be implemented

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

12 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 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 for deliverable 11/2016  Benchmarks to be extended in ESIWACE, the Centre of Excellence in Simulation of Weather and Climate in Europe, if funded

13 CW 2015, Manchester, 04/ Coupling technology benchmarking in IS-ENES2 The end