The Research And Implemtation On Satellite Embedded Operating System Supporting Multicore Processors

With the increasing requirement of on-board information processing capacity, the contradiction between capacity and performance will be more highlighted on the satellite computer system day after day. Compared with single-core processors, multi-core processors perform better at the same power cost. They provide a great help for the contradiction. Under this background, RTOS supporting multi-core processors is to be a new pop research area nowadays. Operating systems with SMP(Symmetric Multi-Processing)have many advantages such as shared memory, higher performance power ratio and earier load balancing which can play a greater role in performance. So this paper will research on the key technologies about how on-board embedded operating systems support multi-core processors and SMP.This paper introduces the architecture of RTEMS(Real Time Executive for Multiprocessor Systems), and analyses the task schedule mechanism, interruption mechanism and synchronization and mutex mechanism in detail. Then it presents corresponding solutions against these key problems facing the implementation of supporting multi-core for RTEMS.In exclusive control between CPU cores, synchronization and mutex mechanism of based nestable Kernel Lock is introduced as a new mechanism. This mechanism solves the deadlock problem that is generated by nesting of normal spinlock. It is also nestable, simple and reliable. On the basis it addresses the system integrity issue effectively and takes full advantage of the high performance of multi-core processors with Multi-core Scheduling Lock.In interrupt management, this paper introduces NS (Non-Spinning) interrupt dynamic dispatch algorithm. It dispatches on whether the interrupt service routine needs the Kernel Lock. The algorithm solves the problem that the interrupt response time fluctuates fiercely which is caused by the uncertainty of the time waiting for the Kernel Lock. Experiments have proved that the algorithm improves real-time property of the multi-core system and effctiveness of response because of the smaller fluctuation of time responding to interruption compared with other ordinary algorithms.In task management, this paper presents an allocation algorithm based global task queue. The algorithm is simple and efficient with the time complexity of O (1). Not only can it efficiently balance overhead, but also it provides real-time protection for system.Finally, we implement the prototype system RTEM~2S (The Real Time Executive for Multi-core & Multi-processor Systems) on the platform with the multi-core processor LEON3. In multi-core simulator, we present an event driven model. By using it, we designs and implements a simulator MSIS(Multi-core Sparc Instruction Simulator). Besides we do tests and analysis both qualitatively and quantitatively for RTEM~2S on MSIS. The experimental results show that RTEM~2S has supported SMP well and the techniques and methods proposed by the paper have achieved desired results.