SC13 Denver, CO

The International Conference for High Performance Computing, Networking, Storage and Analysis

Extreme-Scale Space-Time Parallelism.

Authors: Daniel Ruprecht (University of Lugano), Robert Speck (Forschungzentrum Juelich), Matthew Emmett (Lawrence Berkeley National Laboratory), Matthias Bolten (Universit├Ąt Wuppertal), Rolf Krause (University of Lugano)

Abstract: Time-parallel methods for the integration of time-dependent problems introduce concurrency in the temporal direction in addition to typically used parallelization in space. A recently developed algorithm of this type is the "parallel full approximation scheme in space and time" (PFASST). PFASST performs "sweeps" with a low-order time stepper along a hierarchy of space-time meshes, iteratively computing a collocation solution on multiple time-slices simultaneously. For improved parallel efficiency, an FAS correction allows to use space-time coarsening strategies and thus to reduce the computational cost of sweeps on higher levels. The poster presents novel scaling results of a combination of PFASST with a parallel multi-grid (PMG) solver in space on up to the full IBM Blue Gene/Q system JUQUEEN with 448K cores. It is demonstrated that for large core counts the space-time parallel solver consisting of PFASST plus PMG features significantly better strong scaling capabilities than the pure space-parallel PMG code alone.

Poster: pdf
Two-page extended abstract: pdf

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