On the point of software engineering, the microkernel concept is superior to the monolithic kernel concept. However, it is also widely believed that the microkernel based systems are inherently inefficient. Servent model is a novel operating system constructural model. This model takes servent and exe-flow as its storage and execution abstractions respectively and makes them independent from each other. On the basis of the model, the operating system may achieve higher efficiency than the microkernel system and better extendibility than the monolithic kernel system. A prototype system MiniCore was designed based on this model and developed for the Intel i386 platform. MiniCore is also ported to a route platform. Finally, the performance of the operating system and the model is presented.