Energy Efficient Scheduling of Real Time Tasks on Large Systems

High processing capabilities of today's large systems are also used for real time applications, where executing tasks before their deadline is essential. On the other hand, with increase in the processing capability, energy consumption also increases for such systems. Thus energy efficient execution of real time tasks in such large systems has found to be promising research area in recent time. Scheduling tasks in such large systems using only low level power construct like DVFS is not efficient. In this paper, we have exploited the power consumption pattern of the recent commercial processors and derived a simple power model with a higher granularity for systems have large number of processor with each processor having multi-threading feature. We have then proposed an energy efficient scheduling technique namely, smart allocation policy for executing a set of aperiodic independent real time tasks on large system such that no task misses it deadline. We have analyzed the instantaneous power consumption and the overall energy consumption of the proposed policy along with other five baseline policies for a wide variety of synthetic data sets and real trace data. As execution time of tasks has a significant impact on scheduling and on the overall performance of the system, we have considered six different execution time models of task for our experiment. Experimental evaluation reveals that our proposed policy performs significantly better than baseline policies for all the variations of synthetic data and for real trace data.