@inproceedings{0d6c899e8f1649d892a2c06bd288826e,
title = "A massively space-time parallel N-body solver",
abstract = "We present a novel space-time parallel version of the Barnes-Hut tree code PEPC using PFASST, the Parallel Full Approximation Scheme in Space and Time. The naive use of increasingly more processors for a fixed-size N-body problem is prone to saturate as soon as the number of unknowns per core becomes too small. To overcome this intrinsic strong-scaling limit, we introduce temporal parallelism on top of PEPC's existing hybrid MPI/PThreads spatial decomposition. Here, we use PFASST which is based on a combination of the iterations of the parallel-in-time algorithm parareal with the sweeps of spectral deferred correction (SDC) schemes. By combining these sweeps with multiple space-time discretization levels, PFASST relaxes the theoretical bound on parallel efficiency in parareal. We present results from runs on up to 262,144 cores on the IBM Blue Gene/P installation JUGENE, demonstrating that the spacetime parallel code provides speedup beyond the saturation of the purely space-parallel approach.",
author = "R. Speck and D. Ruprecht and R. Krause and M. Emmett and M. Minion and M. Winkel and P. Gibbon",
year = "2012",
doi = "10.1109/SC.2012.6",
language = "English (US)",
isbn = "9781467308069",
series = "International Conference for High Performance Computing, Networking, Storage and Analysis, SC",
booktitle = "2012 International Conference for High Performance Computing, Networking, Storage and Analysis, SC 2012",
note = "2012 24th International Conference for High Performance Computing, Networking, Storage and Analysis, SC 2012 ; Conference date: 10-11-2012 Through 16-11-2012",
}