The Eventbuilder of the ZEUS experiment is a real-timeparallel data formatting and transport system. It combines data flows originating from various detector components and transfers them to the third level trigger p...
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The Eventbuilder of the ZEUS experiment is a real-timeparallel data formatting and transport system. It combines data flows originating from various detector components and transfers them to the third level trigger processor farm. The Eventbuilder is based on an asynchronous packet-switching transputer network and uses transputer links for bulk data transfer. A high-speed 64x64 custom made crossbar switch allows dynamic linking of any detector component to any branch of third level processor nodes, offering a bandwidth of more than 24 MB/s over a distance of 100 m. Experience gained in operating a transputer network, constructing transputer specific hardware, and developing parallel software is promising. Multi-transputer systems are easy-to-build, can be efficiently programmed in the common high-level language C, and are running stably and reliably.
The scheduling of tasks in distributedreal-timesystems has attracted many researchers in the recent past. The distribute real-time system considered here consists of uniprocessor or multiprocessor nodes connected th...
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ISBN:
(纸本)0818680970
The scheduling of tasks in distributedreal-timesystems has attracted many researchers in the recent past. The distribute real-time system considered here consists of uniprocessor or multiprocessor nodes connected through a multihop network. Scheduling in such a system involves scheduling of dynamically arriving tasks within a node (local scheduling) and migration of tasks across the network (global scheduling) if it is not possible to schedule them locally. Most of the existing schemes on distributedreal-time task scheduling ignore the underlying message scheduling required for global scheduling of tasks. These schemes consider the load on the processors at a node as the basis to migrate tasks from a heavily loaded node (sender) to a lightly loaded node (receiver). We believe that the identification of a receiver node should by based not only on the load on its processors, but also on the availability of a lightly loaded path from the sender to that receiver. In this paper, we present an integrated framework for distributedreal-time dynamic task scheduling (i) by proposing algorithms for transfer, location, and information policies which take into account the states of both the processors and the links, and (ii) by proposing interactions among these policies and schedulers so that the guarantee ratio (ratio of number of tasks guaranteed to the number of tasks arrived) is improved as compared to algorithms where only local scheduling is done. For local scheduling, we use a variation of myopic algorithm [10]. The effectiveness of the proposed framework has been evaluated through simulation.
Concurrent C is an upward-compatible parallel extension of C which runs on a variety of uniprocessors and multiprocessors. A Concurrent C program consists of a set of processes which execute in parallel and interact w...
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Concurrent C is an upward-compatible parallel extension of C which runs on a variety of uniprocessors and multiprocessors. A Concurrent C program consists of a set of processes which execute in parallel and interact with each other by sending messages. Fault-Tolerant (FT) Concurrent C, an extension of Concurrent C, is a tool for writing fault-tolerant distributed programs, based on the replication of critical processes. All details of interaction with replicated (fault-tolerant) processes are handled by the FT Concurrent C runtime system. Consequently, writing fault-tolerant distributed programs is almost the same as writing ordinary distributed programs. In this paper, we briefly describe Concurrent C, discuss its real-time facilities and describe FT Concurrent C.
Although there are some commercial real-time operating systems available on the market today, the common prejudices against their use for implementing control algorithms are still justified. Consequently, most control...
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Although there are some commercial real-time operating systems available on the market today, the common prejudices against their use for implementing control algorithms are still justified. Consequently, most control applications are designed to run on bare hardware, to avoid system overhead and ensure predictable response times throughout the entire application. This paper introduces new concepts for building an operating system, that scales the overhead according to present real-time constraints by adapting its set of services provided, so that any application requirements can be fulfilled provided that sufficient hardware resources are available.
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.
distributedreal-timesystems should be composable out of a set of autonomous components such that important system properties can be derived from the properties of the components. This paper proposes a communication ...
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distributedreal-timesystems should be composable out of a set of autonomous components such that important system properties can be derived from the properties of the components. This paper proposes a communication infrastructure for distributedreal-timesystems that supports this goal. After a discussion of some fundamental conflicts between desirable protocol objectives, the characteristics of different real-time communication protocols are investigated and compared. Finally, a new combination of intra-node and inter-node protocols is presented.
A novel approach, called Aeneas, which is based on the execution state of distributed programs, is proposed in this paper. It is for the real-time performance analysis of distributed programs with reliability-constrai...
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A novel approach, called Aeneas, which is based on the execution state of distributed programs, is proposed in this paper. It is for the real-time performance analysis of distributed programs with reliability-constrains. In Aeneas, there are two important factors, the available data files and the transmission paths of each available data file. Some algorithms are designed to find all the transmission paths of each data file needed while the program executes, count the transmission time for each transmission path, then get the aggregate expression of transmission time, calculate the fastest response time and the slowest response time of distributed programs with reliability-constrains. In order to justify the feasibility and the availability of this approach, a series of experiments have been done. The results show that it is feasible and efficient to evaluate the real-time performance for distributed software with reliability-constrains.
Current trends in real-timesystems identify Java as a new alternative to develop both centralized and distributedreal-timesystems. Many efforts have been devoted to develop the real-time Specification for Java (RTS...
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Current trends in real-timesystems identify Java as a new alternative to develop both centralized and distributedreal-timesystems. Many efforts have been devoted to develop the real-time Specification for Java (RTSJ), and there is substantial ongoing activity to produce a straightforward and valuable distributedreal-time Specification for Java (DRTSJ). The current paper provides a contribution to this latter activity defining, from different angles, a synchronous scheduling service aligned with principles of some popular real-time architectures. This service orchestrates the system in such a way that it provides end-to-end guarantees in the distributed transactions, guaranteeing their timely execution across the network and nodes. The service is described from two points of view: the system one, characterizing a portable model;and the programmer one, defining a distributed object-oriented implementation of a model based on real-time Remote Method Invocation (RTRMI). Finally, it also presents results of an implementation carried out to judge the efficiency of the service, offering a preliminary predictability and performance assessment of a distributedreal-time Java technology.
parallel processing facilitates the real-time implementation of an end-effector velocity controller for elastic robotic manipulators. The approach has potential application in teleoperation.
parallel processing facilitates the real-time implementation of an end-effector velocity controller for elastic robotic manipulators. The approach has potential application in teleoperation.
Designing and reasoning about real-timesystems are difficult activities, in which timing and reactive behaviour requirements add significant complexity to system validation. In this paper, a new technique for distrib...
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Designing and reasoning about real-timesystems are difficult activities, in which timing and reactive behaviour requirements add significant complexity to system validation. In this paper, a new technique for distributed prototyping of real-timesystems is presented. It enables system prototypes to be concurrently developed and tested by a geographically distributed team, in such a way that each developer can validate his or her part of the system against the other parts which are being built in other development sites. A set of tools hits been implemented that supports validation of functional and time behaviour through distributed animation of graphical prototypes with a consistent vision of simulated time.
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