The Design And Realization Of Inter-DVS Based On Utilization Updating Techique

With the abroad application of embedded system, more and more portable devices, such as mobile telephone, PDA(Personal Digital Assistant), MP3 and so on, play a vary important role in people's daily lives. These devices usually operate on batteries with little capacity. If the power consumption is too large, the battery's life will be too short, these devices are useless.Dynamic Voltage Scaling (DVS) is another form of software power saving. It means that the power can be saved through scaling its voltage and frequency dynamically. Because a clock frequency reduction linearly decreases the CMOS circuit's power, and that voltage reduction results in a quadratic power reduction.This paper carries on a detailed classification of dynamic voltage scaling (DVS) algorithms of Embedded System, and makes a detailed analysis to the performance of each kind of algorithms. The existing DVS algorithms can be classified into two kinds: Inter-DVS and Intra-DVS. The Inter-DVS algorithms determine the voltage on a task-by-task basis at each scheduling point while the Intra-DVS algorithms adjust the voltage within an individual task boundary. The main difference between them is whether the slack times are used for the current task or for the tasks that follow.This thesis takes the Utilization Updating DVS algorithms for example, optimizes it based on Linux, through analyzing the Real-Time of the OS in detail, and proposes a new scheduling method that the normal process and the Real-time process adopt different scheduling method, namely NDVS and RDVS, in the case of researching the schedule module of the OS kernel completely.In addition, a realization is designed in this thesis. The realization realizes the power saving embedded Linux OS HIT-Linux with DVS. Based on HIT-Linux, in addition to analyzing the CPU and the power manager IC, I propose the Linux-DVS framework to implement the DVS algorithms. In this framework, every level function component (I use the term component within this thesis for hardware, software, driver, OS and so on) cooperates, thus DVS is supported, and the power saved at last.