Seminars of the Focus Area Complex Systems

Prof. Dr. C. Beta, Prof. Dr. K. Dethloff, Prof. Dr. R. Engbert, Prof. Dr. M. Holschneider, Prof. Dr. W. Huisinga, Prof. Dr. Ralf Metzler, Prof. Dr. A. Pikovsky, Prof. Dr. S. Reich, Prof. Dr. M. Rosenblum, Prof. Dr. G. Rüdiger, Prof. Dr. T. Scheffer, Prof. Dr. F. Scherbaum, Prof. Dr. J. Selbig, Prof. Dr. F. Spahn


Speaker: Nicola Botta, PIK

Title: Semi-automatic parallelization of stencil-based algorithms

Time: Tue, Oct 20, 2009, 1:00pm

Place: PIK, large seminar room in the annex building, Pappelallee

I present a scheme for the semi-automatic parallelization of stencil-based algorithms.

Stencil-based algorithms are simple but general patterns found in many scientific computing applications. Their simplest form, relation-based reductions, is defined in terms of a relation r: T0 -> T1 and of two functions f: T1 -> T2 and h: [T2] -> T3.

Relation-based reductions are easy to implement sequentially, but difficult to parallelize.

The scheme has been implemented in c++ and is based on three constructs: 1) an application-dependent function, usually user-defined, with the type of h, 2) a mean of parallely iterating through a distributed representation of r and f and 3) a generic distributed implementation of data based relation-based reductions.

The scheme allows applications to create objects representing specific parallel distributed stencil-based algorithms in two steps. These objects can then be evaluated in parallel as common function.

The objects support both the computation of the data exchange which has to take place between partitions prior parallel object evaluation and the local access to the exchanged data.

I describe the three constructs and the two steps and apply the scheme to simple examples.

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Past NLD Seminars (1994-2007) & (2008 ...)

Students' seminar: Theoretical Physics, PIK, Modeling & TSA Berlin-Potsdam-Colloquia: PhysGesellschaft Berlin, TU Berlin, Pro Physik, AIP, AEI, MPI-KGF, GFZ, HMI, PIK, AWI, Max Planck Institute for the History of Science, Mathematik, DPG Disputationen, & Vorschau UP

Udo Schwarz, Zentrum für Dynamik komplexer Systeme,
Universität Potsdam, Campus Golm Karl-Liebknecht-Str. 24, 14476 Potsdam, building 28, room 2.107
Phone: (+49-331) 977-1658, Fax : (+49-331) 977-1045

Email: Udo.Schwarz AT

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