HOMMEXX 1.0: a performance-portable atmospheric dynamical core for the Energy Exascale Earth System Model

Abstract

Abstract. We present an architecture-portable and performant implementation of the atmospheric dynamical core (High-Order Methods Modeling Environment, HOMME) of the Energy Exascale Earth System Model (E3SM). The original Fortran implementation is highly performant and scalable on conventional architectures using the Message Passing Interface (MPI) and Open MultiProcessor (OpenMP) programming models. We rewrite the model in C++ and use the Kokkos library to express on-node parallelism in a largely architecture-independent implementation. Kokkos provides an abstraction of a compute node or device, layout-polymorphic multidimensional arrays, and parallel execution constructs. The new implementation achieves the same or better performance on conventional multicore computers and is portable to GPUs. We present performance data for the original and new implementations on multiple platforms, on up to 5400 compute nodes, and study several aspects of the single- and multi-node performance characteristics of the new implementation on conventional CPU (e.g., Intel Xeon), many core CPU (e.g., Intel Xeon Phi Knights Landing), and Nvidia V100 GPU.

Separating Physics and Dynamics Grids for Improved Computational Efficiency in Spectral Element Earth System Models

“…A smaller number of nodes shows much better agreement with the ideal scaling, which highlights a loss of efficiency when running in a higher throughput regime. This is consistent with the results of (Bertagna et al, 2019) who showed that Cori-KNL efficiency can vary with the amount of workload per node.…”

Convection‐Permitting Simulations With the E3SM Global Atmosphere Model

“…See Bertagna et al. (2019) and Bertagna et al. (2020) for a description of our design strategy and initial performance results.…”

“…Our ultimate goal is to make SCREAM as fast as possible on exascale machines by writing it in C++ using the Kokkos library (Carter-Edwards et al, 2014) for performance portability. See Bertagna et al (2019) and Bertagna et al (2020) for a description of our design strategy and initial performance results. We are, however, approaching this goal by first creating a prototype version in Fortran using the existing E3SM atmosphere infrastructure.…”

Using a GPU to Accelerate a Longwave Radiative Transfer Model with Efficient CUDA-Based Methods

“…Bertagna et al also rewrote the Fortran code of the High-Order Methods Modeling Environment (HOMME) in C++ and used the Kokkos library to express on-node parallelism. Then, HOMME achieved good performance on the GPU [32].…”