On Maximizing Reliability of Real-Time Embedded Applications Under Hard Energy Constraint

Abstract

Abstract-The dynamic voltage and frequency scaling (DVFS)technique is the basis of numerous state-of-the-art energy management schemes proposed for real-time embedded systems. However, recent research has illustrated the alarmingly negative impact of DVFS on task and system reliability. In this paper, we consider the problem of assigning processing frequencies to a set of real-time tasks in order to maximize the overall reliability, under given time and energy constraints. First, under the frame-based task model, we formulate the problem as a nonlinear optimization problem and show how to obtain the static optimal solution. Then, we propose online (dynamic) algorithms that detect early completions and adjust the task frequencies at runtime, to improve overall reliability. Furthermore, we extend these solutions to the periodic task model, with both static and dynamic solutions. All our solutions ensure that all timing constraints are met while the cumulative energy consumption of tasks does not exceed the given energy budget. Our simulation results indicate that our algorithms perform comparably to a clairvoyant optimal scheduler that knows the exact workload in advance.Index Terms-Dynamic voltage and frequency scaling, real-time embedded systems, reliability.

Fault-Tolerant Energy-Aware Task Scheduling on Multiprocessor System for Fixed-Priority Real-Time Tasks

“…Zhao et al [18] claim that instead of placing recovery task copies statically for all tasks of periodic task set, modest recovery allowance with dynamically allocated recovery copies helps in achieving high reliability. Zhao et al [19] has considered reliability preservation for energy-constrained systems for frame-based task system (for precedence constraint tasks) as well as for periodic task system to maximize reliability under given energy budget.…”

“…The real-time computing system under consideration is assumed to tolerate transient faults. Generally, transient faults are modeled with Poisson distribution with an average fault rate [19]. Melhem et al [31] showed that reduced supply voltage results in exponentially increased fault rate.…”

Joint optimization of energy efficiency and system reliability for precedence constrained tasks in heterogeneous systems

“…It enables processor element dynamically adjust available frequency levels. To present system-level power model, we adopt the classic one proposed in [30], and the system power consumption is given as following [31]:…”

“…Observed from Eq. 2, it can be easily to deduce that E i ( f i ) is a strictly convex function and reaches its extreme point at f i = f ee = 3 P ind 2C e f f (energy efficient frequency) [31]. It can be deduced that, lower frequencies don't always make for energy saving and there must exists an optimal voltagefrequency pair to achieve minimum energy consumption.…”

Leakage-aware scheduling for embedded real-time systems with (m, k)-constraints

“…Many scheduling techniques (e.g. [42,18,4,33,34,45,46]) have been proposed to reduce the power/energy consumption for real-time embedded systems. Most of them have focused on reducing the dynamic power/energy consumption.…”