Homa: A Receiver-Driven Low-Latency Transport Protocol Using Network Priorities

03/26/2018

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by   Behnam Montazeri, et al.

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Homa is a new transport protocol for datacenter networks. It provides exceptionally low latency, especially for workloads with a high volume of very short messages, and it also supports large messages and high network utilization. Homa uses in-network priority queues to ensure low latency for short messages; priority allocation is managed dynamically by each receiver and integrated with a receiver-driven flow control mechanism. Homa also uses controlled overcommitment of receiver downlinks to ensure efficient bandwidth utilization at high load. Our implementation of Homa delivers 99th percentile round-trip times less than 15 μs for short messages on a 10 Gbps network running at 80 published measurements of an implementation. Simulations show that Homa can operate at higher network loads than pFabric, pHost, or PIAS.