Current trends in embedded applications aim towards implementations with sets of interoperating tasks and elaborate scheduling schemes. The quest for flexibility and universal applicability results in higher resource ...
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Current trends in embedded applications aim towards implementations with sets of interoperating tasks and elaborate scheduling schemes. The quest for flexibility and universal applicability results in higher resource demands and reduced predictability. If the functional and connection problems are handled separately with the aid of appropriate tools, subsequent code generators can convert design specific issues, such as parallel structures in the functional part and the various periodicities in the connection part to linear and deterministic pieces of code. Such implementations do away with complicated run-time scheduling, make better use of the available resources and can be analyzed exhaustively before installation on a target.
We believe we have demonstrated for the first time wavelength-division multiplexing (WDM) all-optical IP tag switching with wavelength conversion and subcarrier multiplexed addressing. Switching over four wavelengths ...
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Current pricing and charging methods for the Internet are not based on actual usage of this service, which leads to unfairness and more important, it does not deliver the right signals through financial incentives to ...
Current pricing and charging methods for the Internet are not based on actual usage of this service, which leads to unfairness and more important, it does not deliver the right signals through financial incentives to network providers to upgrade critical links of their networks. The development of new multimedia applications and the convergence to an integrated services network will foster the tremendous growth of the Internet even more. With the Next Generation Internet not only technical services like bandwidth reservation will be introduced, but also new applications will emerge within the Internet. Charging the Internet in a fashion that provides feedback to users and providers has been proposed since the early '90s, however, only a few implementations and real-world examples are known today. This is due to subsidizing the Internet in its early stages and due to a technical development that did not care much about charging. With the recent redesign of the Internet protocol suite and discussions on multiple service classes in the Internet, architectures for charging and accounting have to be revisited, too. Economic models for the Internet cannot be tested fully and validated in non-real-world environments, because of the unknown user behavior. With this uncertainty over what models and pricing schemes to choose, it is evident that a specific charging and accounting platform will never be accepted by the community. In this paper a novel and flexible architecture for charging and accounting is proposed that provides a wide range of mechanisms and lets researchers experiment in an environment as close as possible to the targeted system. As a first step, four different pricing schemes are described, qualitatively assessed on the proposed platform, and a prototypical implementation performed. One of the economic models that have been implemented on Arrow is based on different service classes including reservation and recalculates prices dynamically depending on the t
The resource management for ASHMEN (ATM over Shared Media networks) is concerned with Quality-of-Service (QoS) support and QoS provision in the local area networking environment in order to offer wide area ATM (Asynch...
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ISBN:
(纸本)0780371720
The resource management for ASHMEN (ATM over Shared Media networks) is concerned with Quality-of-Service (QoS) support and QoS provision in the local area networking environment in order to offer wide area ATM (Asynchronous Transfer Mode) services over shared media networks. Based on a prototypical implementation, including the design of a highly flexible resource management scheme, empirical values in terms of statistical QoS guarantees for delay and throughput have been investigated. The approach developed determines that in-advance performance assumptions can be maintained during the operation of ATM connections between an ATM backbone and ASHMEN-capable end systems attached to a shared media network via an Attachment Device.
In this paper, we suggest interval diagram techniques for formal verification of real-time systems modeled by means of timed automata. Interval diagram techniques are based on interval decision diagrams (IDDs)-represe...
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In this paper, we suggest interval diagram techniques for formal verification of real-time systems modeled by means of timed automata. Interval diagram techniques are based on interval decision diagrams (IDDs)-representing sets of system configurations of, for example, timed automata-and interval mapping diagrams (IMDs)-modeling their transition behavior. IDDs are canonical representations of Boolean functions and allow for their efficient manipulation. Our approach is used for performing both timed reachability analysis and real-time symbolic model checking. We present the methods necessary for our approach and compare its results to another, similar verification technique-achieving a speedup of 7 and more.
The primary/backup with deallocation approach of S. Ghosh et al. (1997) is a strategy for the fault-tolerant online scheduling of hard realtime tasks. In this scheme, tasks are either rejected within a short time afte...
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The primary/backup with deallocation approach of S. Ghosh et al. (1997) is a strategy for the fault-tolerant online scheduling of hard realtime tasks. In this scheme, tasks are either rejected within a short time after the request or guaranteed to be executed even in case of a processor failure. In this paper several heuristics for the guarantee algorithm are investigated. For the first time different processor selection strategies for guarantee algorithms with execution time constraints are compared. In addition, the concept of a decision deadline is introduced which then leads to an extension of the primary and backup checking routines. The thus modified checking routines are shown to achieve a lower rejection ratio for right task deadlines and constrained scheduler execution times than the modification making use of task slack suggested S. Ghosh et al. (1997).
This paper addresses the problem of exploiting simultaneously trade-offs between program memory, data memory and execution time requirements for algorithms specified by synchronous data flow graphs. A code generation ...
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This paper addresses the problem of exploiting simultaneously trade-offs between program memory, data memory and execution time requirements for algorithms specified by synchronous data flow graphs. A code generation model is used, that includes many variable parameters. The search space includes all valid schedules of a graph, different models of buffer organization and different ways of code invocation. An evolutionary algorithm (EA) is applied to this multi-objective optimization problem. This approach is evaluated and compared with existing methods.
In this paper, an internal design model called FunState (functions driven by state machines) is presented that enables the representation of different types of system components and scheduling mechanisms using a mixtu...
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ISBN:
(纸本)9780780358324
In this paper, an internal design model called FunState (functions driven by state machines) is presented that enables the representation of different types of system components and scheduling mechanisms using a mixture of functional programming and state machines. It is shown how properties relevant for scheduling and verification of specification models like boolean dataflow, cyclostatic dataflow, synchronous dataflow, marked graphs, and communicating state machines as well as Petri nets may be represented in the FunState model. Examples of methods suited for FunState are described, such as scheduling and verification. They are based on the representation of the model's state transitions in form of a periodic graph.
Real-time requirements, space constraints, and the tight interlock of functional and interface parts in embedded systems often degrade software reuse to scavenging components from previous work. The presented strategy...
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Real-time requirements, space constraints, and the tight interlock of functional and interface parts in embedded systems often degrade software reuse to scavenging components from previous work. The presented strategy separates concerns, supports development on a high level of abstraction, and relies on the assistance of code generators. This paper points out the benefits of this approach to software reuse. An architectural view separates functional aspects of a system from their connection to the environment. The functionality is modeled as a collection of cooperating extended state machines; it is attached to a physical environment using access routines in a static schedule. Appropriate tools favor the creation of detachable, self-contained components. Functional models that reflect the behavior of a component in the environment are especially fit candidates for finding generic solutions to recurrent problems. For example, a mechanical switch simply corresponds to its counterpart in the model, which will be used with the same confidence as its match. Elements needed to attach a functional solution to specific environments are difficult to reuse. Together with a code generator that creates efficient, deterministic and balanced schedules, such components can be included unaltered in various environments. These measures open up new possibilities for reuse, and because they help to raise the abstraction level for the development work, both software quality and developer productivity improve.
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