The Key Technology Research On Embedded Real-time Operating System

With the coming of the"post-PC era", embedded systems have been applied in every field. The embedded industry has becoming a new growth of IT industry. And its industrial output is over a trillion dollars. As the increasing complexity and scale of embedded system, it is a tendency to use embedded real-time operating system (ERTOS) in embedded equipment. Nowadays, our country has made a great development in ERTOS, but the technology gap with advanced countries is still large. Especially, almost all the strong real-time operating systems are supplied abroad.For domestic shortcomings in ERTOS development , the paper does comprehensive research on it, especially on its real-time performance. By introducing many effective approaches, an ERTOS kernel with strong real-time performance is built.Firstly, considering preemptive priority-based scheduling method of ERTOS, we bring forward an improved multi-priority ready queue algorithm. With O(1) time complexity, the algorithm ensures the stability and real-time performance of scheduling.Moreover, we propose a configurable multi-resolution timer mechanism. Based on the timer resolution configured by user itself, the kernel adopts a double-resolution timer mechanism, which distinguishes normal timer interrupt and high-resolution timer interrupt in complete. With this mechanism, which can reduce the unnecessary cost with strong real-time performance, we resolve the contradiction between real-time performance and system efficiency.Finally, based on the conception of centralized management, the paper handles external interrupts according to the processor features. In order to reduce interrupt latency, the kernel offeres a fast interrupt interface to applications other than the normal one. When an interrupt occurs, it only has 5 stack operations at least. Besides, double stack mechanism is also applied in the kernel, with which the problem of stack overflow caused by interrupt nesting is resolved efficiently.With battery technology not keeping up with the speed of the system energy consumption, we firstly implement dynamic voltage scaling (DVS)...