Fast adaptive diagnosis with a minimum number of tests

  • Authors:
  • Samuel Guilbault;Andrzej Pelc

  • Affiliations:
  • Département d'informatique, Université du Québec en Outaouais, Gatineau, Québec, Canada;Département d'informatique, Université du Québec en Outaouais, Gatineau, Québec, Canada

  • Venue:
  • ISAAC'07 Proceedings of the 18th international conference on Algorithms and computation
  • Year:
  • 2007

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Abstract

We study adaptive system-level fault diagnosis for multiprocessor systems. Processors can test each other and later tests can be scheduled on the basis of previous test results. Fault-free testers correctly identify the fault status of tested processors, while faulty testers can give arbitrary test results. The goal is to identify correctly the status of all processors, assuming that the number of faults does not exceed a given upper bound t, where n is the number of processors. Tests involving disjoint pairs of processors can be performed simultaneously in one round. Two most important measures of quality of a diagnosis algorithm are its worst-case cost (the number of tests used) and time (the number of rounds used). It is known that the optimal worst-case cost of a diagnosis algorithm is n + t - 1. However, the known algorithms of this cost use time Θ(n). We present an algorithm with optimal cost n + t - 1 using time O(log t), provided that the upper bound t on the number of faults satisfies t(t + 1) ≤ n. Hence, for moderate numbers of faults which we assume, our algorithm achieves exponential speed-up, compared to the previously known diagnosis algorithms of optimal cost.