Leaf: Improving QoS for Reconfigurable Datacenters with Multiple Optical Circuit Switches

Facing the huge volume of traffic and intensive traffic dynamics, the traditional datacenter architectures are behind the curve due to the fixed topology and the demand-oblivious nature. Driven by the traffic pattern, the reconfigurable technologies, like optical circuit switches (OCSes), are a promising alternative to further improve throughput when facing traffic dynamics, thanks to the high bandwidth and low reconfiguration time. However, existing works on OCSes are relatively elementary. Some of previous works only deploy single OCS which cannot adapt to large-scale datacenters, while others either cannot guarantee near-optimality or overlook practical issues like limited fiber capacity. These solutions may cause low throughput and long reconfiguration time, resulting in poor QoS. In this paper, we present Leaf to maximize throughput thus to further improve QoS, by deploying multiple OCSes to carry traffic in a cooperation manner. Furthermore, we also show its efficient reconfiguration ability and near-optimality. The formulated problem is a new k-weight limited matching problem and is proven to be N P-hard, which can be solved by a new proposed approximation algorithm with bounded approximation ratio. To evaluate our proposed solution, simulation experiments are conducted with both real-world and synthetic datasets. Compared with state-of-the-arts works, Leaf can improve throughput by 42.16%-68.92%, and reduce runnning time by 68.87%-78.72%.