Mechanisms for cooperative shared memory

  • Authors:
  • David A. Wood;Satish Chandra;Babak Falsafi;Mark D. Hill;James R. Larus;Alvin R. Lebeck;James C. Lewis;Shubhendu S. Mukherjee;Subbarao Palacharla;Steven K. Reinhardt

  • Affiliations:
  • -;-;-;-;-;-;-;-;-;-

  • Venue:
  • ISCA '93 Proceedings of the 20th annual international symposium on computer architecture
  • Year:
  • 1993

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Abstract

This paper explores the complexity of implementing directory protocols by examining their mechanisms primitive operations on directories, caches, and network interfaces. We compare the following protocols: Dir1B, Dir4B, Dir4NB, DirnNB[2], Dir1SW[9] and an improved version of Dir1SW (Dir1SW+). The comparison shows that the mechanisms and mechanism sequencing of Dir1SW and Dir1SW+ are simpler than those for other protocols. We also compare protocol performance by running eight benchmarks on 32 processor systems. Simulations show that Dir1SW+s performance is comparable to more complex directory protocols. The significant disparity in hardware complexity and the small difference in performance argue that Dir1SW+ may be a more effective use of resources. The small performance difference is attributable to two factors: the low degree of sharing in the benchmarks and Check- In/Check-Out (CICO) directives [9].