Research And Design Of Power Management Policies On Operating System Layer For Loongson

Energy consumption of computer system is globally count for much in all energy-intensive devices, power is becoming an important reference factor when corporations or customers purchasing computers. Loongson computers which used processors researched by our own country are concerned for its performance, but its power advantages also becoming an parameter key for the purpose of its widespread.In computer system, power consumption isn't restricted to one device only, but distributed in all devices in one computer. Thus, there are many energy-saving ways specific to different devices. The key point of researching energy-saving ways of computer is to find out the critical device in power consumption, and analyze the possibility of researching for it. After measured the power distribution of Loongson computer in this thesis, we obtained a researching point of power management policies with Loongson 2F processor. Loongson 2F processor surpport for running at many different frequency-levels, we can regulate the processor's frequency dynamically associated with its workload, this will make for energy-saving.CPUFreq subsystem is a framework in Linux kernel, it can make the CPU frequency changed dynamically, each processor can realize the frequency-changing driver on the basic of this framework. Follow up, the thesis analyzes not only the execution flow, important data structures and functions of CPUFreq subsystem, but also introduces the different features of five governors provided by the subsystem. Finally, we design and implement the frequency-changing driver which provided by CPUFreq according to features of Loongson 2F processor.At the last chapter in the thesis, it provides the operating commands in detail according to the CPUFreq frequency-changing driver which has already implemented, it also proves the energy-saving effect through two ways by real test and simulation test. Two test results all indicate that realizing the CPUFreq driver has some advantages compare with keep the CPU in the highest performance status forever, especially when CPU supports voltage be regulated automatically, the superiority will be clearer. Last, at the section of conclusion, the thesis also bring up some outlooks of CPU energy-saving methods.It is valuable for the work in the thesis to get the"National Energy Conservation Product Certification"for the Loongson Computer serials.