ERfair Scheduler with Processor Suspension for Real-Time Multiprocessor Embedded Systems

Proportional fair schedulers with their ability to provide optimal schedulability along with hard timeliness and quality-of-service guarantees on multiprocessors form an attractive alternative in real-time embedded systems that concurrently run a mix of independent applications with varying timeliness constraints. This article presents ERfair Scheduler with Suspension on Multiprocessors (ESSM), an efficient, optimal proportional fair scheduler that attempts to reduce system wide energy consumption by locally maximizing the processor suspension intervals while not sacrificing the ERfairness timing constraints of the system. The proposed technique takes advantage of higher execution rates of tasks in underloaded ERfair systems and uses a procrastination scheme to search for time points within the schedule where suspension intervals are locally maximal. Evaluation results reveal that ESSM achieves good sleep efficiency and provides up to 50% higher effective total sleep durations as compared to the Basic-ERfair scheduler on systems consisting of 2 to 20 processors.