Minimization of task turnaround time for distributed systems

The problem of assigning a partitioned task to a distributed computing system is studied. Considering communication overhead and idle time, it is possible to develop a mathematical model to describe the cost function, which is defined to evaluate the task turnaround time, under a general model of distributed computing systems. Task assignment is formulated as a DU-mapping, which maps a directed acyclic task graph onto an undirected system graph. The search of optimal DU-mapping is NP-complete and is transformed into a state-space search problem. An approach called critical sink underestimate is developed to attain an optimal DU-mapping. This approach allows the most nodes in the state-space tree to be pruned. Experimental results reveal that this method performs very well due to its close evaluation to the real cost