Energy efficient fault-tolerant earliest deadline first scheduling for hard real-time systems

2014 ◽  
Vol 50 (5-6) ◽  
pp. 592-619 ◽  
Author(s):  
Qiushi Han ◽  
Linwei Niu ◽  
Gang Quan ◽  
Shaolei Ren ◽  
Shangping Ren
2017 ◽  
Vol 26 (06) ◽  
pp. 1750091 ◽  
Author(s):  
Linwei Niu ◽  
Wei Li

In this paper, we study the problem of reducing the energy consumption for hard real-time systems scheduled according to either fixed-priority (FP) or earliest-deadline-first (EDF) scheme. To balance the static and dynamic energy consumptions, the concept of critical speed was proposed in previous research. Moreover, when combined with the processor idle/shutdown state, the critical speed was widely used as the lower bound for voltage scaling in literature. In this paper, we show that this strategy might not always be more energy efficient than the traditional DVS strategy and there exists a dynamic tradeoff between these two strategies depending on the job’s work-demand to be finished within certain intervals. To effectively address this issue, we propose a unified approach that combines these two strategies to achieve better overall energy saving performance. Our approach determines the energy-efficient speeds for real-time jobs in their corresponding feasible intervals based on the threshold work-demand analysis. Our experimental results demonstrate that the proposed techniques significantly outperform previous approaches in the overall energy saving performance.


2012 ◽  
Vol 85 (6) ◽  
pp. 1386-1399 ◽  
Author(s):  
Tongquan Wei ◽  
Piyush Mishra ◽  
Kaijie Wu ◽  
Junlong Zhou

2014 ◽  
Vol 644-650 ◽  
pp. 2253-2257
Author(s):  
Jian Lang Wu ◽  
Jing Kai Shi ◽  
Yi Bin Wang

In real-time systems, periodic tasks and aperiodic tasks exist simultaneously. In a uniprocessor system, mainly there are Deferrable Server algorithm (DS) [1], Slack Stealing algorithm (SSA) [2] and their extended version for software/hardware hybrid real-time task scheduling. DS algorithm sets a high priority periodic task server to provide services for aperiodic tasks, while SSA algorithm computes tasks unoccupied time offline, and then schedule aperiodic tasks during the unoccupied period. The two algorithms are both proposed for soft real-time tasks, reducing the response time of the real-time tasks, but cannot guarantee that these aperiodic real-time tasks received can meet deadlines. In this paper, through combination of DS algorithm and EDF (Earliest Deadline First) algorithm [6], a new algorithm called DS-EDF is introduced, which can scheduling hard real-time aperiodic tasks on the DS server. This algorithm is not only suitable for uniprocessor systems, but also has the ability to extend to multiprocessor systems.


2013 ◽  
Vol 1 (4) ◽  
pp. 274-278
Author(s):  
Chafik Arar ◽  
Hamoudi Kalla ◽  
Salim Kalla ◽  
Sonia Sabrina Bendib

Symmetry ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 651 ◽  
Author(s):  
Hyeongboo Baek ◽  
Jaewoo Lee

Hard real-time systems are employed in military, aeronautics, and astronautics fields where deployed systems are susceptible to software faults that can result in functional errors. Thus, there is a need to use fault-tolerant (FT) real-time scheduling. Among the various fault-tolerant real-time scheduling techniques, re-execution has been applied widely to existing real-time systems owing to its simplicity and applicability. However, re-execution requires multiple executions of every task, and some tasks miss their deadlines owing to the prolonged execution time; therefore, it has been found to be suitable for only soft real-time systems. In this paper, we propose an FT policy that can be incorporated into most (if not all) existing real-time scheduling algorithms on multiprocessor systems, which improves the reliability of the target system without a tradeoff against schedulability. As a case study, we apply the FT policy to existing fixed-priority scheduling and earliest deadline zero-laxity scheduling, and we demonstrate that it enhances reliability without schedulability loss.


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