Receiver-driven flow scheduling for commodity datacenters

To achieve scalable performance, datacenter applications (e.g., search and social networking) are designed to have high fanout. However, such a design leads to frequent fabric congestion (e.g., due to incast, imperfect hashing) even when the utilization is low. Such fabric congestion exhibits spatial (e.g., within a rack and across racks) as well as temporal variations. Unfortunately, current approaches infer congestion by focusing on a localized view leading to non-optimal performance. We propose RecFlow, a receiver-based proactive congestion control scheme that uses OpenFlow and ACK spacing to dynamically track changing bottlenecks and reduces buffer overflows while maintaining fairness and high link utilization. Experimental results show that compared to the state-of-the-art, RecFlow achieves negligible packet loss and high goodput while sharing the link capacity fairly between flows.