Optimal granularity of test generation in a distributed system

The problem of test generation for logic circuits is known to be NP-hard, and hence it is very hard to speed up the test generation process due to its backtracking mechanism. The authors present an approach to parallel processing of test generation for logic circuits in a loosely coupled distributed network of general-purpose computers. They analyze the effects of the allocation of target faults to processors, the optimal granularity (grain size of target faults), and the speedup ratio of the multiple-processor system to a single-processor system. To analyze the case in which a test pattern generated for one fault can also be a test pattern for other faults if fault simulation is performed, they introduce a ratio of newly processed faults to target faults and derive the expressions of optimal granularity in cases of both static and dynamic task allocation. They also derive an expression of the speedup of a multiple-processor system in the homogeneous case. The analysis indicates that the speedup approaches N, the number of servers, if the data transfer time per fault and the waiting time per communication are much smaller than the processing time per fault and if the decrease ratio of newly processed faults due to overlapped processing is much smaller than the ratio of newly processed faults.<>