Google Research

Modeling and Control of Google bittide Synchronization

  • Calin Cascaval
  • Martin Izzard
  • Sanjay Lall
  • Tammo Spalink
(2021)

Abstract

Clock synchronization in distributed systems is critical for data center applications, with the maintenance of tight synchronization a challenging problem. In this paper we introduce a distributed system design that removes the need for physical clock synchronization, and instead provides applications with a tightly synchronized logical clock. We discuss the abstract frame model (AFM), a mathematical model that underpins the system synchronization, based on the rate of communication between nodes in a topology without requiring a global clock. We demonstrate that the system remains logically synchronized as long as the processor clocks remain approximately synchronized with respect to real (wall-clock) time. We show that there are families of controllers that satisfy the properties required for existence and uniqueness of solutions to the AFM, and give examples.

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