With an increasing requirement of more flexible real-time applications, e.g. multimedia servers in home networks and real-time database servers, a real-time process scheduler using Worst-Case Execution Time (WCET) is inefficient for optimizing performance. Some soft and firm real-time models have been proposed to deal with this situation. This paper presents a feedback control approach for scheduling processes with imprecise computation, a firm real-time model to produce approximate result of an acceptable quality when the exact result of the desired quality cannot be obtained in time. By introducing feedback control to process scheduling, our approach aims to bind the deadline missing ratio under a varying system workload to reach a tradeoff between the deadline missing ratio and result precision.