Experience with an adaptive globally-synchronizing clock algorithm

Cheng Liao, Margaret Rose Martonosi, Douglas W. Clark

Research output: Contribution to conferencePaperpeer-review

27 Scopus citations


Fast commodity network-connected PC or workstation clusters are becoming more and more popular. This popularity can be attributed to their ability to provide high-performance parallel computing on a relatively inexpensive platform. An accurate global clock is invaluable for these systems, both for measuring network performance and coordinating distributed applications. Typically, however, these systems do not include dedicated clock synchronization support. Previous clock synchronization methods are not suitable here in general, either because of extra, non-commodity hardware requirements or insufficient synchronized clock accuracy. In this paper we present and evaluate an adaptive clock synchronization algorithm. We have implemented and tested the algorithm on our Myrinet-based PC cluster. It is regularly used as part of a parallel performance tool running on the cluster. The algorithm has several important features. First, it does not require any extra hardware support. Second, we show that this algorithm imposes very low overhead on the system and has microsecond-level accuracy. Finally, our results indicate that adding the ability to adaptively adjust the clock's re-synchronization period causes almost no extra overhead while achieving a much better global clock accuracy.

Original languageEnglish (US)
Number of pages9
StatePublished - 1999
EventProceedings of the 1999 11th Annual ACM Symposium on Parallel Algorithms and Architectures, SPAA'99 - Saint-Malo
Duration: Jun 27 1999Jun 30 1999


OtherProceedings of the 1999 11th Annual ACM Symposium on Parallel Algorithms and Architectures, SPAA'99

All Science Journal Classification (ASJC) codes

  • Software
  • Safety, Risk, Reliability and Quality


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