Fachbereich Mathematik und Informatik

CMPP - 2004
Startseite Mathematik und Informatik
Universität Münster

m4_titel_left(COFFEE) ... a research project funded by the  German Research Foundation (DFG).

m4_titel_left(Personnel)  Sergei_Gorlatch
 Holger Bischof
 Jörg Fischer

m4_titel_left(Scope) Following the principle «It takes one Egyptian a million years to build a pyramid, it takes a million Egyptians one year to build a pyramid» efforts have been made in parallel programming to enhance computation speed. Today, many commercial parallel computer architectures are available. However, parallel computing has failed to prevail against sequential computing. The reason for this is the intractability of parallel computers. It is not as easy to program parallel computers concisely to make them work efficiently. A task cannot always be evenly partitioned in subtasks to obtain a performance gain as in the above-mentioned pyramid example.
We hope that collective operations will remedy this situation. These are relatively simple operations for communication, synchronization and other purposes, which are performed commonly by a group of processes. Well-known examples are reduce, scan, etc. Collective operations are designed to substitute of the individual communication between processes, which causes so much trouble in parallel computer programming.

m4_titel_left(Goals) The main goal of the COFFEE project is to develop a viable and formally well-founded methodology of parallel programming based exclusively on collective operations, i. e. avoiding the Send/Receive mechanism of conventional parallel programming. Dijkstras structured programming, which rejects the use of goto transfer in programs, can be regarded as analogous in the sphere of sequential programming.
The subgoals of the COFFEE project are:

  • To explore an equational calculus of collective operations. The equations should correspond to semantic-preserving transformations between parallel computer programs made from collective operations.
  • To investigate cost models for some parallel computer architectures, providing predictability of performance for parallel implementations.
  • To develop engineering principles of parallel programming, taking into account both the equational calculus and the investigated cost models.
  • To experiment on some widely available parallel architectures in the form of case studies.
The COFFEE project is intended to increase awareness of collective operations. We wish to convince experts and users that collective operations are a viable alternative to individual process communication, which we consider responsible for the intractability of parallel programming.

[Last modified: October 10, 2001]

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