ExaSky: Computing the Sky at Extreme Scales

The Argonne-led ExaSky project is one of the main Applications Development efforts within the DOE Exascale Computing Project. The tri-Lab collaboration (Argonne, Lawrence Berkeley, and Los Alamos National Laboratories) has identified a comprehensive program using the HACC and Nyx codes, suitably extended for efficient utilization of exascale resources. The two codes are being used to develop a joint program for verification of gravitational evolution, gasdynamics, and subgrid models in cosmological simulations at very high dynamic range. The project is organized in three overlapping teams focused on exascale code development, large-scale data management, workflows and visualization, and science integration.
Work under the ExaSky umbrella at Argonne includes development of the CRK-HACC cosmological hydrodynamics code and its analysis framework CosmoTools. We are developing a verification program with Nyx to understand the robustness of results obtained by both codes. Additionally, we are collaborating with ECP Software Technology teams on a number of topics such as data reduction, optimization of IO, and data analysis and visualization.
Within the ECP, HACC team members are also involved in work with CoPA, the Co-Design Center for Particle Applications. CoPA has supported making the custom HACC 3-D FFT, SWFFT, available as a separate package. Work is underway on exascale Poisson solvers under CoPA support.