A Performance-Portable Nonhydrostatic Atmospheric Dycore for the Energy Exascale Earth System Model Running at Cloud-Resolving Resolutions

Authors: Luca Bertagna, Oksana Guba, Mark A. Taylor, and James G. Foucar (Sandia National Laboratories); Jeff Larkin (Nvidia Corporation); and Andrew M. Bradley, Sivasankaran Rajamanickam, and Andrew G. Salinger (Sandia National Laboratories)

Abstract: We present an effort to port the nonhydrostatic atmosphere dycore of the Energy Exascale Earth System Model (E3SM) to efficiently run on GPU architectures, specifically targeting cloud-resolving resolutions of 3 km and 1 km. To express on-node parallelism we use the C++ library Kokkos, which allows us to achieve a performance portable code in a largely architecture-independent way. Our implementation is able to achieve 0.97 simulated years per day, running on the full Summit supercomputer when using the GPUs. To the best of our knowledge, this is the highest achievement to date by any global atmosphere dycore running at such resolutions. Moreover, our C++ implementation is on par with (or slightly better than) the original Fortran implementation on CPUs, proving that the GPU port did not compromise the efficiency on conventional CPUs.




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