Sharif Digital Repository

The interaction between fault tolerance and energy consumption is an interesting avenue in the realm of designing embedded systems. In this paper, a scheme for reducing energy consumption in conventional standby-sparing systems is introduced. In the proposed method, the primary unit exploits dynamic voltage scaling (DVS) and dynamic power management (DPM) is employed for the spare unit. The framework which is used in the primary unit is composed of a feedback system to follow up workload along with a three-layer yet light-weight energy manager which guarantees hard real-time constraints of the system. Moreover, an optimal approach (but not practical) as a margin for the minimum energy... 

Low energy consumption and fault tolerance are often key objectives in the design of real-time embedded systems. However, these objectives are at odds, and there is a trade-off between them. Real-time systems usually use system level energy reduction methods, i.e., dynamic voltage scaling (DVS) and dynamic power management (DPM). Also hard real-time systems often use replication to achieve fault tolerance. In this paper, we investigate the impact of system level energy reduction methods on both the reliability and energy consumption of hard real-time systems which use replication for fault tolerance. In this analysis, we have considered four various existing energy management methods: 1)... 

Embedded systems are usually energy constrained. Moreover, in these systems, increased productivity and reduced time to market are essential for product success. To design complex embedded systems while reducing the development time and cost, there is a great tendency to use commercial off-the-shelf ("COTS") devices. At system level, dynamic voltage and frequency scaling (DVFS) is one of the most effective techniques for energy reduction. Nonetheless, many widely used COTS processors either do not have DVFS or apply DVFS only to processor cores. In this paper, an easy-to-implement COTS-based evaluation platform for low-energy embedded systems is presented. To achieve energy saving, DVFS is... 

Two main objectives in designing real-time embedded systems are high reliability and low power consumption. Hardware replication (e.g., standby-sparing) can provide high reliability while keeping the power consumption under control. In this paper, we consider a standby-sparing system where the main tasks on primary cores are scheduled by our proposed peak-power-aware earliest-deadline-first policy while the backup tasks on spare cores are scheduled by our proposed peak-power-aware earliest-deadline-late policy to meet the chip thermal design power (TDP) constraint. These policies provide the best opportunity to shift the task executions as much as possible to minimize execution overlaps... 

Time redundancy (rollback-recovery) and hardware redundancy are commonly used in real-time systems to achieve fault tolerance. From an energy consumption point of view, time redundancy is generally more preferable than hardware redundancy. However, hard real-time systems often use hardware redundancy to meet high reliability requirements of safety-critical applications. In this paper we propose a hardware-redundancy technique with low energy-overhead for hard real-time systems. The proposed technique is based on standby-sparing, where the system is composed of a primary unit and a spare. Through analytical models, we have developed an online energy-management method which uses a slack...