Data-Driven Mapping Using Local Patterns

The problem of mapping a data flow graph onto a reconfigurable architecture has been difficult to solve quickly and optimally. Anytime algorithms have the potential to meet both goals by generating a good solution quickly and improving that solution over time, but they have not been shown to be practical for mapping. The key insight into this paper is that mapping algorithms based on search trees can be accelerated using a database of examples of high quality mappings. The depth of the search tree is reduced by placing patterns of nodes rather than single nodes at each level. The branching factor is reduced by placing patterns only in arrangements present in a dictionary constructed from examples. We present two anytime algorithms that make use of patterns and dictionaries: Anytime A* and Anytime Multiline Tree Rollup. We compare these algorithms to simulated annealing and to results from human mappers playing the online game UNTANGLED. The anytime algorithms outperform simulated annealing and the best game players in the majority of cases, and the combined results from all algorithms provide an informative comparison between architecture choices.