Catching two rabbits: adaptive real-time support for embedded Linux

The trend of digital convergence makes multitasking common in many digital electronic products. Some applications in those systems have inherent real-time properties, while many others have few or no timeli-ness requirements. Therefore the embedded Linux kernels, which are widely used in those devices, provide real-time features in many forms. However, providing real-time scheduling usually induces throughput degradation in heavy multitasking due to the increased context switches. Usually the throughput degrada-tion becomes a critical problem, since the performance of the embedded processors is generally limited for cost, design and energy efficiency reasons. This paper proposes schemes to lessen the throughput degra-dation, which is from real-time scheduling, by suppressing unnecessary context switches and applying real-time scheduling mechanisms only when it is necessary. Also the suggested schemes enable the complete priority inheritance protocol to prevent the well-known priority inversion problem. We evaluated the effec-tiveness of our approach with open-source benchmarks. By using the suggested schemes, the throughput i