The centralized control capability of Software Defined Networking (SDN) presents a unique opportunity for enabling Quality of Service (QoS) routing. For delay sensitive traffic flows, a QoS mechanism efficiently computes path latency and minimizes a controller's response time. At the core of the challenges is how to handle short term network state fluctuations in terms of congestion and latency while guaranteeing the end-to-end latency performance of networking services. The disclosed technology provides a systematic framework that considers active link latency measurements, efficient statistic estimate of network states, and fast adaptive path computation. The disclosed technology can be implemented, for example, as an SDN controller application, and can find optimal end-to-end paths with minimum latency and significantly reduce the control overhead.