Emebedded Operating System Process Scheduling Optimization Based On ScratchPad SRAM

As the embedded systems are being used more and more deeply, people have more and more high command on the performance for the systems. In order to improve the performance, advanced micro processors are more and more used in embedded system. Scratchpad memory equipment is an appellative for a set of memory equipments which are integrated in micro processor chip. Scratchpad SRAM is a kind of Scratchpad memory equipment and it has the characteristic of high reading-writing speed and low power consumption. Recently, lots of advanced micro processors have this kind of on-chip memory equipment integrated in them. Generally, it has 215K memory space.At present, the researches on Scratchpad memory mainly focus on power efficiency and real time. In these researches, Scratchpad memory is mainly utilized to be the environment for reading, writing and running for the program sections. This way, the program which is optimized can get high performance. However, it can't improve the performance of the embedded system as a whole. To improve the performance of the whole embedded system, the substratum of the system should be optimized.To improve the real time for embedded system, in this paper, we propose to optimize the process scheduling of embedded operating system by using Scratchpad SRAM integrated on chip to performs as the environment which the related data and code sections of the process scheduling are loaded. The source code of the embedded operating system is organized so that the related code and data of process-scheduling is separated. And the separated process-scheduling part is compiled to the memory space of Scratchpad SRAM by cross compiler. Then the binary image of the modified embedded operating system is loaded to the appointed memory space by program loader. The code and data sections of process-scheduling part of the whole binary image are loaded to the code and data sections in Scratchpad SRAM respectively and the rest of the image is loaded to the main memory.Experimenting based on the hardware platform of Intel PXA 270, the time that process scheduling of the optimized UC/OS-II takes is reduced about 27% compared to the normal situation where the optimization doesn't take place.In this thesis, it is proved that loading the related data and code of embedded operating system to Scratchpad SRAM can improve the real-time characteristic of process scheduling efficiently.