Fine-grained allocation of compute resources, in terms of configurable clock speed of virtual machines, is essential for processing efficiency and resource utilization of data streaming applications. For a data streaming application, its processing speed is expected to approach the allocated bandwidth as much as possible. Automatic control technology is a feasible solution, but the plant model is hard to be derived. In relation to the model free characteristic, a fuzzy logic controller is designed with several simple yet robust rules. Performance of this controller is verified to out-perform classic controllers in response rapidness and less oscillation. An empirical formula on tuning an essential parameter is obtained to achieve better performance.