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The IEC 61499 is an open standard for the next generation of distributed control and automation. Data Distribution Service for Real-Time Systems (DDS) is a specification of a publish/subscribe middleware for distributed systems, created by the Object Management Group (OMG) to standardize a data-centric publish-subscribe programming model for distributed systems. This paper evaluates the DDS communication...
Hierarchical scheduling is instrumental to efficiently deploy component-based designs and achieve composability. It allows partitioning resources into multiple levels, hiding the complexity within each partition behind its respective interface. In this paper we focus on the network resource, particularly on Ethernet using ordinary COTS switches, and we show how hierarchical scheduling can be efficiently...
In our previous work, we have introduced an adaptive hierarchical scheduling framework as a solution for composing dynamic real-time systems, i.e., systems where the CPU demand of their tasks are subjected to unknown and potentially drastic changes during run-time. The framework uses the PI controller which periodically adapts the system to the current load situation. The conventional PI controller...
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...
Hierarchical scheduling provides a modular framework for integrating, scheduling and guaranteeing timing constraints of compositional real-time systems. In such a scheduling framework, all modules should receive a sufficient portion of the shared CPU to be able to guarantee timing constraints of their internal parts. In dynamic systems i.e., systems where the execution time of tasks are subjected...
The Flexible Time-Triggered communication over Switched Ethernet protocol (FTT-SE) was proposed to overcome the limitation of guaranteeing the real-time communication requirements of conventional switches, and at the same time to support reconfiguration of dynamic adaptive systems. The protocol fragments large messages into a sequence of packets that are individually scheduled. The maximum transmission...
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...
Nowadays, most complex embedded systems follow a distributed approach in which a network interconnects potentially large numbers of nodes. One technology that is being increasingly used is switched Ethernet, but real-time variants of this protocol typically limit scalability. In this paper, we focus on the scalability of the Flexible Time Triggered communication over Switched Ethernet (FTT-SE), which...
Hierarchical scheduling frameworks (HSFs) provide means for composing complex real-time systems from well-defined independently developed and analyzed subsystems. To support shared logical resources requiring mutual exclusive access in two-level HSFs, overrun without payback has been proposed as a mechanism to prevent budget depletion during resource access arbitrated by the stack resource policy...
Supporting resource sharing in multiprocessor architectures is one of the major problems that limit the potential performance benefits of using such architectures for real-time systems. Many approaches and algorithms have been proposed to support resource sharing, however, most of them impose either high blocking times on tasks or require a large memory allocation. In this paper we investigate the...
In a hierarchical scheduling framework, a resource can be shared among modules with different criticality levels. In our recently introduced adaptive hierarchical scheduling framework, modules receive a dynamic portion of the CPU during run-time. While providing temporal isolation is one of the main advantages of hierarchical scheduling, in an adaptive framework, for example when the CPU is overloaded,...
The complexity of Networked Embedded Systems (NES) has been growing steeply, due to increases both in size and functionality, and is becoming a major development concern. This situation is pushing for paradigm changes in NES design methodologies towards higher composability and flexibility. Component-oriented design technologies, in particular supported by server-based scheduling, seem to be good...
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