SCHEDULE: NOV 10-16, 2012
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A Massively Space-Time Parallel N-Body Solver
SESSION: Numerical Algorithms
EVENT TYPE: Papers
TIME: 2:00PM - 2:30PM
SESSION CHAIR: Costas Bekas
AUTHOR(S):Robert Speck, Daniel Ruprecht, Rolf Krause, Matthew Emmett, Michael Minion, Mathias Winkel, Paul Gibbon
ROOM:355-EF
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 space-time parallel code provides speedup beyond the saturation of the purely space-parallel approach.
Chair/Author Details:
Costas Bekas (Chair) - IBM Research - Zurich
Robert Speck - University of Lugano
Daniel Ruprecht - University of Lugano
Rolf Krause - University of Lugano
Matthew Emmett - Lawrence Berkeley National Laboratory
Michael Minion - Stanford University
Mathias Winkel - Forschungzentrum Juelich
Paul Gibbon - Forschungzentrum Juelich
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A Massively Space-Time Parallel N-Body Solver
SESSION: Numerical Algorithms
EVENT TYPE:
TIME: 2:00PM - 2:30PM
SESSION CHAIR: Costas Bekas
AUTHOR(S):Robert Speck, Daniel Ruprecht, Rolf Krause, Matthew Emmett, Michael Minion, Mathias Winkel, Paul Gibbon
ROOM:355-EF
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 space-time parallel code provides speedup beyond the saturation of the purely space-parallel approach.
Chair/Author Details:
Costas Bekas (Chair) - IBM Research - Zurich
Robert Speck - University of Lugano
Daniel Ruprecht - University of Lugano
Rolf Krause - University of Lugano
Matthew Emmett - Lawrence Berkeley National Laboratory
Michael Minion - Stanford University
Mathias Winkel - Forschungzentrum Juelich
Paul Gibbon - Forschungzentrum Juelich
Click here to download .ics calendar file