2.2.8 Free topology

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2.2.8 Free topology

Basic idea: Mapping of data relations (e.g., domain decomposition) onto the processes/nodes such that geometrical neighbors are represented by an edge in the graph of the topology.

Geometry

$\begin{figure}\unitlength0.15\textwidth \begin{picture}(6,7) \put(3,3){\circle... ...(1,5){\makebox(0,0){4}} \put(5,5){\makebox(0,0){5}} \end{picture} \end{figure}$

Topology

$\begin{figure}\unitlength0.07\textwidth \begin{picture}(12,14) \savebox{\opbox}... ...put(2,1.5){\line(3,1){3}} \put(10,1.5){\line(-3,1){3}} \end{picture}\end{figure}$

Up to links per node necessary.
Diameter can be reduced to .
Only as virtual topology available.
Very efficient hardware is necessary, especially the passing of data over a node (hop) should not influence the arithmetic performance of that node at all.
$\Longrightarrow$ Communication and arithmetics should run in parallel on one node (e.g., T805 by Inmos).
Support by parallel extensions of OS and libraries (PARIX, PVM, MPI).

Gundolf Haase 2000-03-20