Energy efficient scheduling for real time tasks using static and dynamic approaches

Abstract

Real time Embedded systems have geared up their applications in the field of smart phones mobile devices automobile and medical instrumentation Along with the growth of technology the functional requirements of the systems have also grown to multi folds To accommodate these ever increasing functional requirements the hardware has to be designed to include the maximum capability which in turn increases the power consumption In CMOS devices the power consumption is directly proportional to the operating frequency So the power consumption has to be dynamically managed using the software techniques Dynamic Voltage and Frequency Scaling DVFS feature provided in most of the recent processors has enabled the power optimization through software. The operating frequency of the processor can be reduced on the fly through the software Many processors in the market today have the DVFS support with multiple voltage frequency levels newlineThe execution time of the tasks can be stretched to use the laxity by reducing the clock frequency The factor by which the frequency is reduced from the maximum clock frequency is called the slow down factor The slow down factors are calculated using the off line and the on line techniques off line techniques reclaim the laxity based on the worst case execution time whereas on line techniques reclaim the laxity based on the actual execution time of the tasks The factors that are to be considered during the design of the energy efficient scheduling algorithms are Deadline constraints Complexity the number of frequency switching and energy consumption The timing requirement of the tasks has to be met as most of the real time systems are hard newline newline