Local Time Stepping on High Performance Architectures

You are cordially invited to attend the PhD Dissertation Defense of Max RIETMANN on Tuesday, May 12th 2015 at 10h30 in room A34 (Red building)

Abstract:
Modeling problems that require the simulation of hyperbolic PDEs (wave equations) on large heterogeneous domains have potentially many bottlenecks. We attack this problem through two techniques: the massively parallel capabilities of graphics processors (GPUs) and local time stepping (LTS) to mitigate any CFL bottlenecks on a multi-scale mesh. Many modern supercomputing centers are installing GPUs due to their high performance, and extending existing seismic wave propagation software to use GPUs is vitally important to give application scientists the highest possible performance. In addition to this architectural optimization, LTS schemes avoid performance losses in meshes with localized areas of refinement. Coupled with the GPU performance optimizations, the derivation and implementation of a Newmark LTS scheme enables next-generation performance for real-world applications. Included in this implementation is work addressing the load-balancing problem inherent to multi-level LTS schemes, enabling scalability to hundreds and thousands of CPUs and GPUs. These GPU, LTS, and scaling optimizations accelerate the performance of existing applications by a factor 30 or more, and enable future modeling scenarios previously made unfeasible by the cost of standard explicit time-stepping schemes.

Dissertation Committee:

• Prof. Olaf Schenk, Università della Svizzera italiana, Switzerland (Research Advisor)
• Prof. Rolf Krause, Università della Svizzera italiana, Switzerland (Internal Member)
• Prof. Igor Pivkin, Università della Svizzera italiana, Switzerland (Internal Member)
• Prof. Michael Bader, TU Munich, Germany (External Member)
• Prof. Andreas Fichtner, ETH Zurich, Switzerland (External Member)
• Prof. Marcus Grote, University of Basel, Switzerland (External Member)