A quantitative study based on direct measurement on embedded processors limiting context siwtches for energy saving

Priority based preemptive schedulers are preferred over non-preemptive schedulers due to their flexibility to accommodate real time tasks based on criticality. The overhead associated with a preemptive scheduler is high and with increased number of preemptions and the associated context switches, the execution pattern of tasks become highly unpredictable at run time. In this paper, an effort is made to provide an insight into the significance of controlling context switches during real time application development. The system under study consists of an ARM7 LPC2148 microcontroller, whose energy consumption measurement is carried out with the help of MBED NXP 1768 controller. A study is done by analytical verification and a software simulation using embedded C with Keil uVision IDE. The energy consumed by the processor with and without context switches is verified experimentally by direct measurement. The two factors considered for analysis are increased delay and the augmented energy dissipation during a context switch. It is seen that a substantial saving of time and energy is associated with every context switch