Schedulability-Driven Frame Packing for Multi-Cluster Distributed Embedded Systems

We present an approach to frame packing for multi-cluster distributed embedded systems consisting of time-triggered and event-triggered clusters, interconnected via gateways. In our approach, the application messages are packed into frames such that the application is schedulable. Thus, we have also proposed a schedulability analysis for applications consisting of mixed event-triggered and time-triggered processes and messages, and a worst case queuing delay analysis for the gateways, responsible for routing inter-cluster traffic. Optimization heuristics for frame packing aiming at producing a schedulable system have been proposed. Extensive experiments and a real-life example show the efficiency of our frame-packing approach

사물인터넷 애플리케이션의 적응형 동적 스케줄링 기법

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 컴퓨터공학부, 2019. 2. 하순회.IoT시스템은매우다른성능과기능을가진이기종스마트장치로구성된분산임베디드시스템이다. IoT시스템에서일반적으로리소스요구사항과실시간요구사항이서로 다른 많은 IoT 애플리케이션들이 동시에 실행된다. 또한, 전력 소비 및 장치 수명과 같은 비 기능적 특성이 중요하게 고려된다. IoT 애플리케이션은 언제든지 추가되거나 제거 될 수 있으며 런타임에 디바이스 상태가 변경 될 수 있다. 이 같이 시스템은 동적 특성을 갖기 때문에 IoT 애플리케이션을 스마트 디바이스에 매핑/스케줄링 하는 것은 매우까다로운문제이다.이문제를해결하기위해점진적매핑및글로벌재매핑의두 가지 스케줄링 기법으로 구성된 새로운 적응적 스케줄링 기법을 제안한다. 동적 환경 변화에 대한 빠른 응답을 제공하기 위해 점진적 매핑 방법을 제안하며, 정적 상태에서 비 기능적 특성에 기초하여 주어진 목적 함수를 최적화하기 위해 주기적으로 IoT 애플리케이션의 전체 태스크를 모두 다시 스케줄링 하는 유전 알고리즘 기반 글로벌 재 매핑 방법은 제안한다. 제안 된 스케줄링 방법의 두 가지 성능 지표로 애플리케이션 수용 비율 및 에너지 소비량을 사용하였으며, 성능 및 실용성은 무작위로 생성 된 시나리오를 사용한 시뮬레이션 환경을 통해 검증한다.An IoT system can be regarded as a distributed embedded system that is composed of heterogeneous smart devices with very different performance and functions. Also many IoT applications that have different resource requirements and real-time requirements will run concurrently in the IoT system. In addition, non-functional properties such as power consumption and device lifetime are considered important. Since an IoT application can be added or removed anytime and the device status may change at run-time, the system is unprecedentedly dynamic in its configuration, which brings up a challenging scheduling problem of IoT applications onto the smart devices. To tackle this problem, we propose a novel adaptive scheduling technique that consists of two scheduling techniques, incremental and global. An incremental heuristic method is proposed to provide fast responsiveness to dynamically changing configuration. During the steady-state operation, a GA-based method is applied to perform global rescheduling of IoT applications periodically to optimize a given objective function based on non-functional properties. We use the acceptance ratio of new applications and energy consumption as two performance metrics of the proposed scheduling method. The viability of the proposed approach is verified by extensive simulations with randomly generated scenarios.Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v List of Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. Problem Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Target IoT system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Motivational Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Problem Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3. Schedulability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1 Transformation of a Task Graphs to Independent Tasks . . . . . . . . . . 10 3.2 Schedulability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Proposed Mapping Technique . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 Incremental Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.2 Global Re-mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5. Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 5.1 Benchmarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 5.2 Experiment 1 (Incremental Mapping) . . . . . . . . . . . . . . . . . . . 23 5.3 Experiment 2 (Global Re-mapping) . . . . . . . . . . . . . . . . . . . . 25 5.4 Experiment 3 (Sensitivity Analysis) . . . . . . . . . . . . . . . . . . . . 27 6. RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 요 약 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Maste

Exploring Alternatives to use Master/Slave Full Duplex Switched Ethernet for Avionics Embedded Applications

The complexity of distributed real-time systems, including military embedded applications, is increasing due to an increasing number of nodes, their functionality and higher amounts of exchanged data. This higher complexity imposes major development challenges when nonfunctional properties must be enforced. On the other hand, the current military communication networks are a generation old and are no longer effective in facing such increasingly complex requirements. A new communication network, based on Full Duplex Switched Ethernet and Master/slave approach, has been proposed previously. However, this initial approach is not efficient in terms of network bandwidth utilization. In this paper we propose two new alternative approaches that can use the network bandwidth more efficiently. In addition we provide a preliminary qualitative assessment of the three approaches concerning different factors such as performance, scalability, complexity and flexibility