Global Commutative and Associative Reduction Operations in Faulty SIMD Hypercubes

  • Authors:
  • C. S. Raghavendra;M. A. Sridhar

  • Affiliations:
  • -;-

  • Venue:
  • IEEE Transactions on Computers
  • Year:
  • 1996

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Abstract

We consider the problem of computing a global commutative and associative operation, also known as semi-group operation, (such as addition and multiplication) on a faulty hypercube. In particular, we study the problem of performing such an operation in an n-dimensional SIMD hypercube, Qn, with up to n驴 1 node and/or link faults. In an SIMD hypercube, during a communication step, nodes can exchange information with their neighbors only across a specific dimension.Given a set of at most n驴 1 faults, we develop an ordering d1, d2, ..., dn of n dimensions, depending on where the faults are located. An important and useful property of this dimension ordering is the following: if the n-cube is partitioned into k-subcubes using the first k dimensions of this ordering, namely d1, d2, ... dk for any 2 驴k驴n, then each k-subcube in the partition contains at most k驴 1 faults. We use this result to develop algorithms for global sum. These algorithms use 3n驴 2, n + 3 log n + 3 log log n, and n + log n + 4 log log n + O(log log log n) time steps, respectively.