509 research outputs found
Restart-Based Fault-Tolerance: System Design and Schedulability Analysis
Embedded systems in safety-critical environments are continuously required to
deliver more performance and functionality, while expected to provide verified
safety guarantees. Nonetheless, platform-wide software verification (required
for safety) is often expensive. Therefore, design methods that enable
utilization of components such as real-time operating systems (RTOS), without
requiring their correctness to guarantee safety, is necessary.
In this paper, we propose a design approach to deploy safe-by-design embedded
systems. To attain this goal, we rely on a small core of verified software to
handle faults in applications and RTOS and recover from them while ensuring
that timing constraints of safety-critical tasks are always satisfied. Faults
are detected by monitoring the application timing and fault-recovery is
achieved via full platform restart and software reload, enabled by the short
restart time of embedded systems. Schedulability analysis is used to ensure
that the timing constraints of critical plant control tasks are always
satisfied in spite of faults and consequent restarts. We derive schedulability
results for four restart-tolerant task models. We use a simulator to evaluate
and compare the performance of the considered scheduling models
Scheduling Techniques for Operating Systems for Medical and IoT Devices: A Review
Software and Hardware synthesis are the major subtasks in the implementation of hardware/software systems. Increasing trend is to build SoCs/NoC/Embedded System for Implantable Medical Devices (IMD) and Internet of Things (IoT) devices, which includes multiple Microprocessors and Signal Processors, allowing designing complex hardware and software systems, yet flexible with respect to the delivered performance and executed application. An important technique, which affect the macroscopic system implementation characteristics is the scheduling of hardware operations, program instructions and software processes. This paper presents a survey of the various scheduling strategies in process scheduling. Process Scheduling has to take into account the real-time constraints. Processes are characterized by their timing constraints, periodicity, precedence and data dependency, pre-emptivity, priority etc. The affect of these characteristics on scheduling decisions has been described in this paper
์ต์ ECU๋ณด๋๋ฅผ ํ์ฉํ์ฌ ์ํํธ์๋ฌ๋ค์ ์ค์๊ฐ ๋ณต๊ตฌํ๋ ๊ธฐ๋ฒ
ํ์๋
ผ๋ฌธ (์์ฌ) -- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ์ปดํจํฐ๊ณตํ๋ถ, 2020. 8. ์ด์ฐฝ๊ฑด.This dissertation presents the fault-tolerant real-time scheduling using dynamic mode
switch support of modern ECU hardware. This dissertation first describes the optimal
capacity of the Periodic Resource which contains harmonic periodic task set using
the exact time supply function.We show that the optimal capacity can be represented
as sum of the each individual utilization of the task in the harmonic periodic task set
for both normal state(i.e. no faults) and faulty state. Then, this dissertation proposes
non-critical task overlapping technique by only using the idle time intervals of the Periodic
Resource in order to overlap the non-critical tasks which ensures no additional
capacity increase. Finally, this dissertation proposes the basic form of the Periodic
Resources in order to efficiently use the dynamic mode switch support. Next, we also
proposes the bin-packing heuristic algorithm that considers both making sub-taskset
as a one Periodic Resource and Periodic Resource wide bin-packing which has the
pseudo-polynomial time complexity. Experimental results show that the proposed
algorithm performs better than the traditional partitioned fixed-priority scheduling
approach and partitioned mixed-criticality scheduling approach. Also, the achievement
is made up to 18% in terms of the total needed cores compared to traditional
partitioned fixed-priority approach for making the given input task set schedulable.๋ณธ ๋
ผ๋ฌธ์์๋ ํจ์จ์ ์ธ ์ฌ๊ตฌ์ฑ๊ฐ๋ฅ ์์คํ
์ฌ์ฉ์ ์ํ ๊ณ์ธต๊ธฐ๋ฐ ์ค์๊ฐ ๊ฒฐํจ ๊ฐ๋ด ์ค์ผ์ค๋ง ๊ธฐ๋ฒ์ ์ ์ํ๋ค. ๋ณธ ์ฐ๊ตฌ๋ ์ฃผ๊ธฐ ์์ ๋ชจ๋ธ์ ๊ธฐ๋ฐ์ผ๋ก, ์ต์ ์ฃผ๊ธฐ ์์ ์๋ฒ์ ์ฉ๋์ ์ฃผ๊ธฐ ์์ ๋ชจ๋ธ์ด ๊ฐ์ง๋ ์ค์๊ฐ ์ฃผ๊ธฐ ํ์คํฌ ์
์ ์ ํธ๋ผ์ด์ ์ด์
์ ํฉ์ผ๋ก ์ ์ํ๋ค. ๋ณธ ๋
ผ๋ฌธ์ ํด๋น ์ต์ ์๋ฒ ์ฉ๋์ ์์คํ
์ด ์ ์ ๋์ํ ๋์ ์ค๋์ ํ ๋ ๋ชจ๋์ ๋ํด์ ์ ์ํ๋ค. ๋ค์์ผ๋ก, ๋น์ค์ ํ์คํฌ ์
๋ค์ ์ค์ ์ฃผ๊ธฐ ์์ ์๋ฒ์ ์ฌ๋ถ ๊ณต๋ฐฑ ์๊ฐ์ ํ์ฉํด ์๋ฒ ์ฉ๋์ ์ฆ๊ฐ ์์ด ๋น์ค์ ํ์คํฌ๋ฅผ ์ค์ ์ฃผ๊ธฐ ์์ ์๋ฒ์ ํ ๋นํ๋ ๋ฐฉ๋ฒ๋ก ์ ์ ์ํ๋ค. ๋ง์ง๋ง์ผ๋ก ๋ณธ ๋
ผ๋ฌธ์ ์ฃผ๊ธฐ ์์ ์๋ฒ ๋จ์์ ํํฐ์
๊ธฐ๋ฒ๊ณผ ์ฃผ๊ธฐ ํ์คํฌ๋ฅผ ํ๋์ ์ฃผ๊ธฐ ์์ ์๋ฒ๋ก ๋ง๋๋ ๋นํจํน ํด๋ฆฌ์คํฑ ์๊ณ ๋ฆฌ์ฆ์ ์ ์ํ๋ค. ์คํ ๊ฒฐ๊ณผ, ๋ณธ ๋
ผ๋ฌธ์์ ์ ์ํ ์๊ณ ๋ฆฌ์ฆ์ ๊ธฐ์กด์ ์ฌ์ฉ๋์๋ ํํฐ์
๊ธฐ๋ฐ ์ฐ์ ์์ ์ค์ผ์ค๋ง ์๊ณ ๋ฆฌ์ฆ๊ณผ ํํฐ์
๊ธฐ๋ฐ ์ฐ์ ์์ ํผ์ก ์ค์๋ ์๊ณ ๋ฆฌ์ฆ๋ณด๋ค ๋ ์์ ์์ ์ฝ์ด์ ๊ฐ์๋ฅผ ๋์ถ ํ ์ ์์์ ๋ณด์ธ๋ค. ์คํ๊ฒฐ๊ณผ๋ฅผ ๊ธฐ๋ฐ์ผ๋ก, ๋ณธ ์ฐ๊ตฌ์์ ์ ์ํ ์๊ณ ๋ฆฌ์ฆ์ ์ฌ๊ตฌ์ฑ๊ฐ๋ฅ ์์คํ
์ ํ์ฉํ๋ค๋ฉด ๊ธฐ์กด ๋ฐฉ๋ฒ ๋๋น ์ต๋ 18%์ ์ฝ์ด์ ๊ฐํจ๊ณผ๋ฅผ ๊ธฐ๋ํ ์ ์๋ค.1 Introduction 1
1.1 Motivation and Objective 1
1.2 Approach 2
1.3 Organization 6
2 System Model 7
3 Schedulability Analysis 10
3.1 Background 10
3.2 Optimal Capacity Analysis During Normal State 14
3.3 Optimal Capacity Analysis During Fault State 16
3.4 Periodic Resource Wide Schedulability Test 20
3.5 Non-Critical Task Overlapping 24
4 Proposed Approach 26
4.1 Minimum Harmonic Partitions of the Task Set 26
4.2 Proposed Heuristic Algorithm 28
4.2.1 Choosing Detection method 28
4.2.2 Packing Minimum Harmonic Partitions 29
4.2.3 Packing Free Tasks 30
4.2.4 Packing Non-Critical Tasks 31
4.3 Algorithm Description 32
5 Evaluation 35
5.1 Experimental Setup 35
5.2 Simulation Results 36
5.2.1 Free Task Bin-Packing 38
5.2.2 Minimum Harmonic Partitions Bin-Packing 40
5.2.3 Effect of Non-Critical Task Overlapping 43
5.2.4 Effect of State-Wise Computation 45
6 Related Works 46
6.1 Hierarchical Fault-Tolerant Real-Time Scheduling 46
6.2 Error Detection Method 46
7 Conclusion 48
References 50Maste
Performance Analysis of Preemptive Based Uniprocessor Scheduling
All the real-time systems are boundย with response time constraints, or else, there is a risk ofย severe consequences, which includes failure. The System will fail when not able to meet the requirements accordingย to the specifications. The problem of real-time scheduling is very vast, ranging from uni-processor to complicated-multiprocessor. In this paper, we have compared the performance of real-time tasks that should be scheduled properly, to get optimum performance. Analysis methodology and the concept of optimization leads to the design of appropriate scheduling. We have doneย the analysisย among RM and EDFย algorithm that are important for scheduling in uni-processor
Adaptive Fault Tolerance and Graceful Degradation Under Dynamic Hard Real-time Scheduling
Static redundancy allocation is inappropriate in hard realtime systems that operate in variable and dynamic environments, (e.g., radar tracking, avionics). Adaptive Fault Tolerance (AFT) can assure adequate reliability of critical modules, under temporal and resources constraints, by allocating just as much redundancy to less critical modules as can be afforded, thus gracefully reducing their resource requirement. In this paper, we propose a mechanism for supporting adaptive fault tolerance in a real-time system. Adaptation is achieved by choosing a suitable redundancy strategy for a dynamically arriving computation to assure required reliability and to maximize the potential for fault tolerance while ensuring that deadlines are met. The proposed approach is evaluated using a real-life workload simulating radar tracking software in AWACS early warning aircraft. The results demonstrate that our technique outperforms static fault tolerance strategies in terms of tasks meeting their timing constraints. Further, we show that the gain in this timing-centric performance metric does not reduce the fault tolerance of the executing tasks below a predefined minimum level. Overall, the evaluation indicates that the proposed ideas result in a system that dynamically provides QOS guarantees along the fault-tolerance dimension
Software Fault Tolerance in Real-Time Systems: Identifying the Future Research Questions
Tolerating hardware faults in modern architectures is becoming a prominent problem due to the miniaturization of the hardware components, their increasing complexity, and the necessity to reduce the costs. Software-Implemented Hardware Fault Tolerance approaches have been developed to improve the system dependability to hardware faults without resorting to custom hardware solutions. However, these come at the expense of making the satisfaction of the timing constraints of the applications/activities harder from a scheduling standpoint. This paper surveys the current state of the art of fault tolerance approaches when used in the context real-time systems, identifying the main challenges and the cross-links between these two topics. We propose a joint scheduling-failure analysis model that highlights the formal interactions among software fault tolerance mechanisms and timing properties. This model allows us to present and discuss many open research questions with the final aim to spur the future research activities
Energy-Efficient Fault-Tolerant Scheduling Algorithm for Real-Time Tasks in Cloud-Based 5G Networks
ยฉ 2013 IEEE. Green computing has become a hot issue for both academia and industry. The fifth-generation (5G) mobile networks put forward a high request for energy efficiency and low latency. The cloud radio access network provides efficient resource use, high performance, and high availability for 5G systems. However, hardware and software faults of cloud systems may lead to failure in providing real-time services. Developing fault tolerance technique can efficiently enhance the reliability and availability of real-time cloud services. The core idea of fault-tolerant scheduling algorithm is introducing redundancy to ensure that the tasks can be finished in the case of permanent or transient system failure. Nevertheless, the redundancy incurs extra overhead for cloud systems, which results in considerable energy consumption. In this paper, we focus on the problem of how to reduce the energy consumption when providing fault tolerance. We first propose a novel primary-backup-based fault-tolerant scheduling architecture for real-time tasks in the cloud environment. Based on the architecture, we present an energy-efficient fault-tolerant scheduling algorithm for real-time tasks (EFTR). EFTR adopts a proactive strategy to increase the system processing capacity and employs a rearrangement mechanism to improve the resource utilization. Simulation experiments are conducted on the CloudSim platform to evaluate the feasibility and effectiveness of EFTR. Compared with the existing fault-tolerant scheduling algorithms, EFTR shows excellent performance in energy conservation and task schedulability
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