Changing how the operating system handles interrupt processing and scheduling can greatly reduce the difference between worst-case and average-case message latencies, thus increasing a program's performance.
Changing how the operating system handles interrupt processing and scheduling can greatly reduce the difference between worst-case and average-case message latencies, thus increasing a program's performance.
The automation of today's large-scale industrial systems relies on the operation of distributed controller devices that perform local computations and exchange information via communication networks. The subject o...
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The automation of today's large-scale industrial systems relies on the operation of distributed controller devices that perform local computations and exchange information via communication networks. The subject of this paper is the development of a family of shared-medium industrial communication protocols that support the transmission of real-time (RT) and nonreal-time (nRT) data among distributed controller devices. Different from existing protocols, we suggest to incorporate information that is available from the control application in the protocol definition. As a result, our protocols dynamically change the bandwidth allocation on the shared medium according to the instantaneous communication requirements while ensuring hard RT guarantees. Following the recent developments in industrial automation, our protocols can be realized as software layers on top of low-cost conventional Ethernet.
Modern complex embedded systems are evolving into mixed-criticality systems in order to satisfy a wide set of non-functional requirements such as security, cost, weight, timing or power consumption. Partitioning is an...
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Modern complex embedded systems are evolving into mixed-criticality systems in order to satisfy a wide set of non-functional requirements such as security, cost, weight, timing or power consumption. Partitioning is an enabling technology for this purpose, as it provides an environment with strong temporal and spatial isolation which allows the integration of applications with different requirements into a common hardware platform. At the same time, embedded systems are increasingly networked (e.g., cyber-physical systems) and they even might require global connectivity in open environments so enhanced communication mechanisms are needed to develop distributed partitioned systems. To this end, this work proposes an architecture to enable the use of data-centric real-time distribution middleware in partitioned embedded systems based on a hypervisor. This architecture relies on distribution middleware and a set of virtual devices to provide mixed-criticality partitions with a homogeneous and interoperable communication subsystem. The results obtained show that this approach provides low overhead and a reasonable trade-off between temporal isolation and performance.
This paper presents a survey of results in developing real-time CORBA, a standard for rear-time management of distributed objects. This paper includes background on two areas that have been combined to realize Rear-Ti...
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This paper presents a survey of results in developing real-time CORBA, a standard for rear-time management of distributed objects. This paper includes background on two areas that have been combined to realize Rear-time CORBA: the CORBA standards that have been produced by the international Object Management Group;and techniques for distributedreal-time computing that have been produced in the research community. The survey describes major RT CORBA research efforts, commercial development efforts, and standardization efforts by the Object Management Group.
In a real-time database system, an application supports a mix of transactions. These include the real-time transactions that require completion by a given deadline. time-critical requirements also exist in many distri...
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In a real-time database system, an application supports a mix of transactions. These include the real-time transactions that require completion by a given deadline. time-critical requirements also exist in many distributed multi-media system applications. Existing concurrency control procedures introduce excessive delays due to non-availability of data resources. In this study, we ignore the delays incurred by ordinary transactions, in order to achieve a non-interference mode of execution (near parallel) for the time-critical transactions. For this purpose, a data allocation model has been studied. It is a stochastic process model based on the use of two-phase locking. It highlights the available possibilities for reductions of delays for time-critical transactions within a distributedreal-time database systems. Based on the new conceptual model, modified synchronization techniques for time-critical transactions have been proposed.
This paper presents an integrated approach for specification and design of software for distributed hard real-timesystems. The approach adopts a graph-based model, combined with a pre-run-time scheduling. This gives ...
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In this paper, we describe a general approach for dynamic and intelligent reconfiguration of real-timedistributed control systems that utilizes the IEC 61499 function block model. This work is central to the developm...
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In this paper, we describe a general approach for dynamic and intelligent reconfiguration of real-timedistributed control systems that utilizes the IEC 61499 function block model. This work is central to the development of distributed intelligent control systems that are inherently adaptable and dynamically reconfigurable. The approach that is used takes advantage of distributed artificial intelligence at the planning and control levels to achieve significantly shorter up-front commissioning times as well as significantly more responsiveness to change. This approach is based on object-oriented and agent-based methods, and aims at overcoming the difficulties associated with managing real-time reconfiguration of an intelligent manufacturing system.
Many real-timesystems must control their CPU utilizations in order to meet end-to-end deadlines and prevent overload. Utilization control is particularly challenging in distributedreal-timesystems with highly unpre...
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Many real-timesystems must control their CPU utilizations in order to meet end-to-end deadlines and prevent overload. Utilization control is particularly challenging in distributedreal-timesystems with highly unpredictable workloads and a large number of end-to-end tasks and processors. This paper presents the Decentralized End-to-end Utilization CONtrol (DEUCON) algorithm, which can dynamically enforce the desired utilizations on multiple processors in Such systems. In contrast to centralized control schemes adopted in earlier works, DEUCON features a novel decentralized control structure that requires only localized coordination among neighbor processors. DEUCON is systematically designed based on recent advances in distributed model predictive control theory. Both control-theoretic analysis and simulations show that DEUCON can provide robust utilization guarantees and maintain global system stability despite severe variations in task execution times. Furthermore, DEUCON can effectively distribute the computation and communication cost to different processors and tolerate considerable cornmunication delay between local controllers. Our results indicate that DEUCON can provide a scalable and robust utilization control for large-scale distributedreal-timesystems executing in unpredictable environments.
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