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Real-time locking protocols employ progress mechanism(s) to ensure that resource-holding jobs are scheduled. These mechanisms are required to bound the duration of priority-inversion blocking (pi-blocking) for jobs sharing resources. Examples of such progress mechanisms include priority inheritance and priority donation. Unfortunately, some progress mechanisms can cause any job, including those that...
Semi-partitioned scheduling has become the subject of recent interest for multiprocessors due to better utilization results, compared to conventional global and partitioned scheduling algorithms. Under semi-partitioned scheduling, a major group of tasks are assigned to fixed processors while a low number of tasks are allocated to more than one processor. Various task assigning techniques have recently...
This paper presents the model splitting method for large-scale interactive network simulation, which addresses the separation of concerns between network researchers, who focus on developing complex network models and conducting large-scale network experiments, and simulator developers, who are concerned with developing efficient simulation engines to achieve the best performance on parallel platforms...
This paper presents the first real-time multiprocessor locking protocol that supports fine-grained nested resource requests. This locking protocol relies on a novel technique for ordering the satisfaction of resource requests to ensure a bounded duration of priority inversions for nested requests. This technique can be applied on partitioned, clustered, and globally scheduled systems in which waiting...
This paper addresses the problem of scheduling periodic parallel tasks on a multi-resource platform, where tasks have real-time constraints. The goal is to exploit the inherent parallelism of a platform comprised of multiple heterogeneous resources. A resource model is proposed, which abstracts the key properties of any heterogeneous resource from a scheduling perspective. A new scheduling algorithm...
The synchrophasor technology has become focus of many theoretical, conceptual and practical studies lately due to an increased opportunity to improve power system reliability and security through enhanced monitoring, protection and control. The paper provides a survey of signal processing, communication and networking issues surrounding this topic so that professionals from related areas can benefit...
Ethernet switches are increasingly used in real-time distributed systems as a technical solution to guarantee the timeliness in communications. However, there are still limitations related to real-time behavior caused by the limited number of priority levels and the possibility of memory overruns with consequent message losses. These limitations can be eliminated using a master/slave technique such...
Time synchronization is crucial to Wireless Sensor Networks (WSNs) due to the requirement of coordination between sensor nodes. Existing secure time synchronization protocols of WSNs introduce high overhead when used for global time synchronization. In this paper, we propose a lightweight secure global time synchronization protocol for WSNs. In the proposed protocol, a broadcast synchronization packet...
Ethernet is a popular technology for industrial networking thanks to its low cost and high bandwidth. The current proposals to achieve real-time communication over Ethernet do not consider the determinism of the control applications resulting in inefficient use of bandwidth resources. We proposed a protocol stack architecture that works with standard Ethernet to address this problem. This paper describes...
PTIDES, a programming model for distributed real-time systems, was proposed previously. The model captures both the functionality of the system and the desired timing of interactions with the environment. The PTIDES simulator supports simulation of both of these aspects. In this work, we focus on the PTIDES development environment in the context of applications drawn from the control of electric power...
This paper presents a self-stabilizing distributed clock synchronization protocol in the absence of faults in the system. It is focused on the distributed clock synchronization of an arbitrary, non-partitioned digraph ranging from fully connected to 1-connected networks of nodes while allowing for differences in the network elements. This protocol does not rely on assumptions about the initial state...
Fault-tolerant clock synchronization is the foundation of synchronous architectures such as the Time-Triggered Architecture (TTA) for dependable cyber-physical systems. Clocks are typically local counters that are increased with a given rate according to real time, and clock synchronization algorithms ensure that any two clocks in the system read about the same value at about the same point in real...
In uniprocessor real-time systems, resource sharing is usually done using protocols such as Stack Resource Policy, Priority Ceiling Protocol and Priority Inheritance Protocol. Unfortunately these protocols did not work as expected on real-time multiprocessor systems. Such problem must be addressed with different approaches like Multiprocessor Priority Ceiling Protocol (MPCP) and Multiprocessor Stack...
This paper presents the A-Stack, a real-time protocol stack for time-synchronized, multi-channel and slotted communication in multi-hop wireless networks. The stack is developed to meet the reliability, latency and accuracy requirements of real-time applications such as wireless automation and wireless structural health monitoring and to provide a flexible development environment for such applications...
The IEEE 1588 standard could synchronizes independent clocks running on separate nodes of a distributed measurement and control system to a high degree of accuracy and precision. But the standard did not present the method to implement the protocol in detail. An implementation of the IEEE 1588 based on an FPGA is presented in this paper. And the result of the experiment shows this method could achieve...
This article describes our experience from the implementation of PRISM in the Castalia simulator. PRISM is a recently-proposed protocol for real-time monitoring in single-hop and multi-hop wireless sensor networks. The protocol allows to define the maximum number of nodes, the requirements on the network synchronization and the data-rate in a flexible manner, in order to accommodate for different...
Cyber Physical Systems (CPS) comprise the integration of embedded computer systems and the physical processes that these computer systems interact with. Examples of such systems stretch from small embedded devices, e.g., intelligent sensor systems, to larger and often complex industrial systems, e.g., industrial automation systems. These systems are not only subject to functional requirements, but...
In this paper we propose a synchronization protocol for resource sharing among independently-developed real-time systems on multi-core platforms. The systems may use different scheduling policies and they may have their own local priority settings. Each system is allocated on a dedicated processor (core). In the proposed synchronization protocol, each system is abstracted by an interface which abstracts...
In real time scheduling, preemption is one of the causes of run time overhead and large memory requirements. This paper focuses on reducing the number of preemptions in Earliest Deadline First (EDF) scheduling using a technique called Dynamic Preemption Threshold Scheduling (DPTS) in uniprocessor platform. This method is an improvement over existing threshold algorithms, but the complexity is slightly...
The production needs and the more complex working sessions in agricultural field ask for machine cluster in order to achieve a parallel and complete treatment of crops and fields. All heterogeneous or homogeneous machines of the cluster, both in series and in parallel, have to be synchronized to match safety requirements and to comply with task control requirements. The synchronization specifications...
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