LAMCS: A leakage aware DVFS based mixed task set scheduler for multi-core processors

Abstract

This paper proposes Leakage Aware Multi-Core Scheduler (LAMCS), an energy efficient mixed task set dynamic voltage and frequency scaling scheduler for multi-core processors. LAMCS schedules mixed task set where hard and soft real-time tasks co-exist. It takes care of all the deadline constraints of hard real-time tasks and response time constraints of soft real-time tasks. LAMCS achieves energy efficiency by considering static and dynamic energy consumptions. The static energy saving is achieved by shutting down the core(s) for a duration greater than a threshold whenever it is feasible. The dynamic energy saving is achieved by applying DVFS whenever possible. DVFS lengthens the execution intervals by decreasing the voltage and frequency of the core which may reduce the chances of shutdown. This increases energy consumption because of other factors such as preemptions, cache flushes etc. LAMCS minimizes these factors using procrastination. The energy efficiency is achieved while satisfying all the scheduling constraints of mixed task set. It tries to achieve minimum response time for all the soft real-time tasks and meets all deadlines of hard real-time tasks. The experimental results with synthetically generated benchmark program suites show that the proposed energy efficient solution shows appreciable energy savings as compared to the existing solutions.