Firefly Clock Synchronization

Overview

Firefly is Google's ultra-accurate clock synchronization protocol designed specifically for data center environments. Google has published full technical details of Firefly in a SIGCOMM paper, enabling the research and industry communities to understand and potentially adopt the approach.

The protocol is designed to serve a wide range of precision timing use cases, from ML job scheduling (where synchronization helps coordinate collective communication across thousands of accelerators) to financial-exchange-grade precision timing requirements. Standard protocols such as PTP (IEEE 1588) can suffer from asymmetric network delays and software jitter that limit achievable accuracy; Firefly addresses these constraints with hardware-assisted timestamping and Google's large-scale deployment experience.