Welcome to the rudimentary old-style homepage of

Dr. Scient. Jesper Larsson Träff

who used to be Chief Researcher at
NEC Laboratories Europe, NEC Europe Ltd located in St. Augustin, Germany, until NEC made the regrettable decision to close down this research unit with effect from 31.12.2009. After one year and a half at Research group for Scientific Computing, Faculty of Computer Science at the University of Vienna, I am now at the Technical University of Vienna (TU Wien) as the head of the group on Parallel Computing.


PErformance Portability and Programmability of HEterogeneous many-core aRchitectures.

MPI development and research

Practically (as well as theoretically) efficient implementations of MPI, the Message-Passing Interface, for the NEC-Cray SX-series, the Earth Simulator, and other NEC systems. This is done together with other members of the NEC Laboratories Europe MPI Team.

Specifically, I work on regular and irregular collective communication operations (broadcast, reductions, gather, scatter, alltoall, etc.), MPI datatypes, MPI-2 one-sided communications, and MPI topology functions for various interconnects, toplogies, and architectures, eg. SMP-clusters with hierarhical communication systems. I am interested in algorithms and implementations that are portable across a range of architectures and interconnects. Since collective operations will also be found (perhaps implicitly) in other, higher-level parallel programming frameworks, this work has relevance beyond MPI.

I participate(d) in the MPI Forum which has in 2008 and 2009 brought out consolidated versions of the MPI standard (MPI 2.1 and MPI 2.2) and is now discussing more wide ranging extensions to MPI (MPI 3.0).

Research - what I would like to do more

Advanced computer architectures:
Multi-core parallelization:
Models of parallel computation. Design and implementation of parallel algorithms. Algorithms support for parallel (communication) libraries. Library and interface support for parallel programming. Parallel programming languages. Experimental algorithmics. Graph algorithms. Combinatorial optimization. Theory of computation. Recursion theory. Computational complexity.

A Not So RECENT Book: Practical PRAM ProgrammingtheBookCover

A textbook (with Jörg Keller and Christoph W. Keßler) on the PRAM, emulation of the PRAM in the hardware of the SB-PRAM, the PRAM programming language FORK, and the PRAM algorithms library PAD, published by Wiley, 2000.

(Co)edited stuff

LNCS4192 PARCO 33(9) LNCS4854 LNCS5415 MPI-2.1 MPI-2.2 Scientific Programming 17(4) LNCS6586

Education and degrees - how I did not become what I am

University of Copenhagen, 1980-1989, mathematics, computer science and assorted. Degree in computer science (major, DIKU: Datalogisk Institut, Københavns Universitet) and mathematics (minor, indeed).

Master's Thesis (August 1989): Memoization and its use in lazy and incremental program generation (with Torben Amtoft); supervisor: Neil D. Jones.

PhD thesis (June 1995): Distributed and parallel graph algorithms: models and experiments; supervisor: Jens Clausen.

Doctoral Dissertation (Danish: doktordisputats): Aspects of the efficient implementation of the Message Passing Interface (MPI)

1990 to March 1992 at the now-defunct European Computer-Industry Research Center (ECRC) in Munich.

1992 to January 1995 PhD student at DIKU.

February 1995 to October 1997 Research Associate at the Max-Planck-Institut für Informatik in Saarbrücken in the Algorithms and Complexity Group (AG1) of Kurt Mehlhorn.

November 1997 to July 1998 Research Associate at Technische Universität München at the Lehrstuhl für Effiziente Algorithmen of Ernst Mayr.

Since August 1998 Research Staff at NEC Laboratories Europe (formerly C&C Research Laboratories)

Best Marathon: 2.59:31 (Copenhagen, May 1994). Best Halfmarathon: 1.25:23 (Saarbrücken, March 2000). Half-marathon in Vienna 2010, 2011.

Very much non-speaking part in Kolle - Ein Leben für Liebe und Sex

Some publications

An up-to-date list of mainstream computer science publications can be found in the dblp computer science bibliography.

For citations (there are not many) use the NEC Research Institute Citeseer.


Message-Passing Interface (MPI) related

Library of PRAM Algorithms and Data structures

Page created sometime in 1996 by Jesper Larsson Träff, his own (web)master. Last serious update: July 4th, 2008.

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