Bittide: Control Time, Not Flows

The computing industry has seen explosive growth, with the recent surge in AI pushing the boundaries of distributed systems. A common focus in this landscape is the pursuit of lower latencies and reduced uncertainty. This paper presents a different perspective through bittide, a novel approach to distributed system design. We argue that for many large-scale applications, predictability is more critical than achieving the lowest possible wall-clock latency. bittide offers this predictability through a decentralized clock synchronization mechanism that establishes logical synchrony across a network. This paper details the first hardware implementation of an 8-node bittide network using off-the-shelf FPGAs. Through experiments with various network topologies, we demonstrate that bittide achieves tight frequency alignment and robustly handles varying physical latencies. Our results validate that the system establishes a consistent notion of logical time, enabling predictable distributed computation at scale with zero in-band overhead and clock cycle accurate scheduling.