(Almost) No Cost Clock Synchronization

Abstract

We show how synchronized clocks can be realized in a distributed system as a byproduct of a common communication paradigm where processors periodically perform broadcasts. Our approach decouples the precision concern-limiting how much correct clocks can differ from each other-and the accuracy concern-limiting how much any correct clock can differ from real time-of clock synchronization. Given a system that guarantees only precision, we develop a protocol whereby high accuracy can be achieved on demand. In this manner, the "lazy" protocol we obtain incurs the cost of high accuracy only when needed while keeping the basic synchronization procedure extremely simple and cheap.