Simultaneous hardware and time redundancy with online task scheduling for low energy highly reliable standby-sparing system

Abstract

Standby-sparing is one of the common techniques in order to design fault-tolerant safety-critical systems where the high level of reliability is needed. Recently, the minimization of energy consumption in embedded systems has attracted a lot of concerns. Simultaneous considering of high reliability and low energy consumption by DVS is a challenging problem in designing such a system, since using DVS has been shown to reduce the reliability profoundly. In this article, we have studied different schemes of standby-sparing systems from the energy consumption and reliability point of view. Moreover, we propose a new standby-sparing scheme which addresses both reliability and energy consumption jointly together. This scheme uses a simple energy management coupled with an online task scheduler which tries to dispatch those ready tasks which are expected to lead to high reliability and low energy consumption in the system. The effectiveness of the proposed scheme has been shown on TGFF under stochastic workloads. The results show 52% improvement on energy saving compared to the conventional hot standby-sparing system. Moreover, two orders of magnitude higher reliability is obtained on average, while preserving the same level of energy saving as compared to the state-of-the-art low-energy standby-sparing system (LESS).