Experience with an adaptive globally-synchronizing clock algorithm

Abstract

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 ...