# SCHEDULE: NOV 16-21, 2014

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pTatin3D: High-performance Methods for Long-Term Lithospheric Dynamics

SESSION: Earth and Space Sciences

EVENT TYPE: Papers

TIME: 2:30PM - 3:00PM

SESSION CHAIR: Katrin Heitmann

AUTHOR(S):Dave A. May, Jed Brown, Laetitia Le Pourhiet

ROOM:391-92

ABSTRACT:

Simulations of long-term lithospheric deformation involve post-failure analysis of high-contrast brittle materials driven by buoyancy and processes at the free surface. Geodynamic phenomena such as subduction and continental rifting take place over millions year time scales, thus require efficient solution methods. We present pTatin3D, a geodynamics modelling package utilising the material-point-method for tracking material composition, combined with a multigrid finite-element method to solve heterogeneous, incompressible visco-plastic Stokes problems. Here we analyze the performance and algorithmic tradeoffs of pTatin3D’s multigrid preconditioner. Our matrix-free geometric multigrid preconditioner trades flops for memory bandwidth to produce a time-to-solution $>2\times$ faster than the best available methods utilising stored matrices (plagued by memory bandwidth limitations), exploits local element structure to achieve weak scaling at $30\%$ of FPU peak on Cray XC-30, has improved dynamic range due to smaller memory footprint, and has more consistent timing and better intra-node scalability due to reduced memory-bus and cache pressure.

Chair/Author Details:

Katrin Heitmann (Chair) - Argonne National Laboratory

Dave A. May - ETH Zurich

Jed Brown - Argonne National Laboratory

Laetitia Le Pourhiet - Pierre and Marie Curie University

Paper provided by the ACM Digital Library

Paper also available from IEEE Computer Society