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Low-Energy Standby-Sparing for Hard Real Time Systems

Alireza Ejlali
Bashir Al-Hashimi
Petru Eles Author homepage

IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Volume 31, No. 3, March 2012, pp. 329-342.

Time-redundancy techniques are commonly used in real-time systems to achieve fault tolerance without incurring high energy overhead. However, reliability requirements of hard real-time systems that are used in safety-critical applications are so stringent that time-redundancy techniques are sometimes unable to achieve them. Standby sparing as a hardwareredundancy technique can be used to meet high reliability requirements of safety-critical applications. However, conventional standby-sparing techniques are not suitable for low-energy hard real-time systems as they either impose considerable energy overheads or are not proper for hard timing constraints. In this paper we provide a technique to use standby sparing for hard real-time systems with limited energy budgets. The principal contribution of this work is an online energy-management technique which is specifically developed for standby-sparing systems that are used in hard real-time applications. This technique operates at runtime and exploits dynamic slacks to reduce the energy consumption while guaranteeing hard deadlines. We compared the low-energy standby-sparing (LESS) system with a low-energy time-redundancy system (from a previous work). The results show that for relaxed time constraints, the LESS system is more reliable and provides about 26% energy saving as compared to the time-redundancy system. For tight deadlines when the time-redundancy system is not sufficiently reliable (for safety-critical application), the LESS system preserves its reliability but with about 49% more energy consumption.

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[EAE12] Alireza Ejlali, Bashir Al-Hashimi, Petru Eles, "Low-Energy Standby-Sparing for Hard Real Time Systems", IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Volume 31, No. 3, March 2012, pp. 329-342.
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