Exascale finite/spectral element simulations

In this thesis, we present contributions by author and his collaborators to improve the efficiency of high-order spectral/finite element simulations (SEM/FEM) on state-of-the-art exascale and pre-exascale supercomputers with general purpose graphics processing units (GPUs). We briefly discuss the exascale computing landscape and the challenges involved in running high-order SEM/FEM simulations on these machines. Then we present contributions which span four important aspects of high-order SEM/FEM simulations. Firstly, we present representative benchmarks for SEM/FEM applications and use those to benchmark new GPU based exascale systems in order to understand their scalability characteristics. Secondly, we present a parallel partitioner suitable for the exascale era that is characterized by large local problem sizes. Our partitioner is based on recursive spectral bisection and is able to partition a mesh in parallel while preserving load balance and reducing mes- sage volume between partitions. Thirdly, we address one of the main bottlenecks in the SEM/FEM simulations: the coarse-grid solve of the p−Multigrid preconditioner used for solving the pressure Poisson equation. We introduce a novel two-level Schwarz based coarse solver which has the potential to scale well on the exascale machines due to its low communication and increased parallelism. Finally, we present a domain specific compiler framework to improve the productivity of the application engineers who use GPU-based supercomputers by reusing domain specific optimization patterns.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Computer Science

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Ratnayaka Mudiyanselage, Thilina Bandara

Contributors dc:contributor

• Fischer, Paul
• Olson, Luke
• Kloeckner, Andreas
• Rowe, Kris

• Hpc
• Gpu
• Mpi
• Graph Partitioning
• Schwarz Methods
• Coarse-grid
• P-multigrid
• Loopy
• Programming Models
• Clang
• Exascale Computing

Statement dc:rights

• Copyright 2024 Thilina Ratnayaka

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/125706

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F125706