1. A method implemented by a computing device to determine a root cause of a performance issue in a software defined networking (SDN) network using flow statistics maintained by hosts in the network, the computing device coupled to a network monitoring system that collects real-time network and cloud metrics in the network, the method comprising: receiving a request to perform a root cause analysis (RCA) for a first flow in the network that is experiencing a performance issue; obtaining flow path information for flows in the network; obtaining flow statistics for the flows in the network, wherein the flow statistics are end-to-end flow statistics maintained by one or more hosts in the network; and executing an RCA algorithm for the first flow, wherein the RCA algorithm determines a root cause of a performance issue experienced by the first flow based on the flow path information and the flow statistics.