A mapping heuristic for minimizing network contention

The combinatorial optimization problem of assigning tasks of a parallel program to processing nodes (pn's) of a parallel system is a well-known NP-hard problem. In this paper a new greedy heuristic for compile-time mapping of tasks without precedence constraints is proposed. The solution is addressed to modern multicomputers based on k-ary n-cube direct interconnection networks exploiting the e-cube routing algorithm and the wormhole flow control strategy. The proposed algorithm takes into account communication delays due to network blocking of colliding messages. Results achieved on several program-derived graphs with up to 784 tasks demonstrate the effectiveness of the approach followed.