RNOS—A middleware platform for low-cost packet-processing devices

The software platform Real-time Network Operating System (RNOS) allows a natural domain-specific modeling of applications for single CPU systems. Using real-time calculus, the system parameters can be explored and weak points of the system can be exposed early in the design cycle. In a second step, modeled application can be implemented seamlessly on top of RNOS. The results obtained with the real system are comparable with the results obtained in the analysis, which is one of the major goals of this chapter. There are several open questions that are investigated further. One issue is related to the granularity of tasks and the corresponding impact on delay, throughput, and overhead. A next question is related to the assignment of deadlines. The current implementation adds a static deadline to each packet. At least for multimedia flows, deadlines could be added depending on its current state, for example, a buffer level. The provided calculus needs to be extended in order to cope with this extension. A final issue is the analysis of tradeoffs related to the batch processing in terms of a better cache usage, a smaller overhead, and an increased packet delay.