Idle workstations in a network represent a significant computing potential. In particular, their processing power can be used by parallel-distributed programs that treat the network as a loosely-coupled multiprocessor...
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This conference proceedings contains 27 papers. The main subjects are shared memory multiprocessors, achievement of causal consistency, semantics of distributed services, storage management, message-passing systems, c...
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This conference proceedings contains 27 papers. The main subjects are shared memory multiprocessors, achievement of causal consistency, semantics of distributed services, storage management, message-passing systems, clock synchronization algorithms, high speed network control, analysis of communication protocols, reasoning about probabilistic algorithms, and totally asynchronous systems.
We describe the control protocols of the PARIS experimental network. This high bandwidth network for integrated communication (data, voice, video) is currently operational as a laboratory prototype. It will also be de...
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ISBN:
(纸本)9780897914048
We describe the control protocols of the PARIS experimental network. This high bandwidth network for integrated communication (data, voice, video) is currently operational as a laboratory prototype. It will also be deployed within the AURORA Testbed that is part of the NSF/DARPA Gigabit Networking program. The high bandwidth dicates the need of specialized hardware to support faster packet handling and control protocols. A new network control architecture is presented which exploits the specialized hardware in order to support the expected real time needs of future traffic. In particular, since control information can be distributed quickly, decisions can be made based upon more complete and accurate information. In some respects, this has the effect of having the benefits of centralized control (e.g. easier bandwidth resource allocation to connections), while retaining the fault-tolerance and scalability of a distributed architecture.
Processes in concurrent logic programs communicate and synchronize using shared single-assignment variables. Communication is performed via unification operations, while synchronization is performed through input matc...
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ISBN:
(纸本)9780897914048
Processes in concurrent logic programs communicate and synchronize using shared single-assignment variables. Communication is performed via unification operations, while synchronization is performed through input matching. The more expressive concurrent logic languages employ atomic unification as the basic communication primitive. Atomic unification can be thought of as an atomic transaction that either fails with no trace or succeeds in writing on all of the necessary writable variables occurring in the unification instance. This paper presents a distributed variable server algorithm that can be used as the key component in a distributed implementation of concurrent logic languages with atomic unification. The variable server provides an abstraction in which processes can act as if all of the shared variables are local. It thus allows programs to be written for a shared memory model and executed in a system in which memory is distributed. We rigorously specify the requirements the variable server must fulfill, present an algorithm satisfying the specification, and prove its correctness with respect to the specification. The algorithm has been implemented for the language Flat Concurrent Prolog (FCP) and is incorporated in the distributed version of the Logix system.
The main contribution of this paper is the Cancelback Protocol, an extension of the Time Warp mechanism that handles storage management. It includes both fossil collection, the recovery of storage for messages and sta...
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The main contribution of this paper is the Cancelback Protocol, an extension of the Time Warp mechanism that handles storage management. It includes both fossil collection, the recovery of storage for messages and states that can never again influence the computation, and cancelback, the recovery of storage assigned to messages and states at times so far in the future that their memory would be better used for more immediate purposes. It guarantees that Time Warp is optimal in its storage requirements when run in shared memory, i.e. Time Warp will successfully complete a simulation using no more space than it would take to execute the same simulation with the sequential event list algorithm. This is better by a factor of two than the only previously published result. Without this protocol (or equivalent) Time Warp's behavior can be unstable;hence it should be considered an essential part of Time Warp mechanism, rather than simply a refinement. In addition we also prove that asynchronous conservative algorithms, including all of the Chandy-Misra-Bryant (CMB) mechanisms, are not optimal;they cannot necessarily execute a simulation in the same amount of space as a sequential execution. In some cases a simulation requiring space n+k when executed sequentially might require O(nk) space when executed on n processors by CMB.
To provide high availability for services such as mail or bulletin boards, data must be replicated. One way to guarantee consistency of replicated data is to force service operations to occur in the same order at all ...
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ISBN:
(纸本)089791404X
To provide high availability for services such as mail or bulletin boards, data must be replicated. One way to guarantee consistency of replicated data is to force service operations to occur in the same order at all sites, but this approach is expensive. In this paper, we propose lazy replication as a way to preserve consistency by exploiting the semantics of the service's operations to relax the constraints on ordering. Three kinds of operations are supported: operations for which the clients define the required order dynamically during the execution, operations for which the service defines the order, and operations that must be globally ordered with respect to both client ordered and service ordered operations. The method performs well in terms of response time, amount of stored state, number of messages, and availability. It is especially well suited to applications in which most operations require only the client-defined order.
The proceedings contains 15 papers. The following topics are dealt with: A macro-preprocessor for the simulation language Network II.5;model instantiation for query-driven simulation in active KDL;simulating a complex...
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ISBN:
(纸本)0818620676
The proceedings contains 15 papers. The following topics are dealt with: A macro-preprocessor for the simulation language Network II.5;model instantiation for query-driven simulation in active KDL;simulating a complex software system;simulation of final stop consonants in speech perception using the bicameral neural network model;effect of data compression of ERP signals preprocessed by FWT algorithm upon a neural network classifier;optimization of a digital neuron design;simulation of an expert model-based adaptive controller;the role of simulation in developing game playing strategies;a computer simulation for a space-time satellite positioning system;application of extreme value theory to the analysis of a network simulation;simulation of RAM-based asynchronous sequential circuits;numerical modeling of the conformational transition of a spiral focusing surface;nonlinear operator equations and applications to modelling;distributed simulation using distributed control systems;and modeling the cost of resource allocation in distributed control.
A high-speed network is a new environment motivated by recent advances in transmission technology. The high-speed environment requires that the network node operate (fast) based solely on local information (at least m...
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ISBN:
(纸本)089791404X
A high-speed network is a new environment motivated by recent advances in transmission technology. The high-speed environment requires that the network node operate (fast) based solely on local information (at least most of the time). This fact implies properties that are much different than those existing in current architectures and algorithms for traditional large-area networks. The new environment poses new challenges for the network architect and the algorithm designer. In this paper we present principles of operation for the basic control functions of a high-speed network with an arbitrary topology, we then suggest a design of such a network. In the architecture we design, on one hand a node can try to transmit asynchronously, without reservation, as much as it can, and on the other hand the network access and flow control will ensure no loss, fair access to the network, no deadlocks and self-routing. The switching over this network requires only a single buffer on each side of the full-duplex links. The transmission via the receiving buffer can be 'cut through', i.e., the incoming packet can be sent to the next link before the entire packet has arrived (unlike 'store-and-forward'). A dynamic self-routing technique is implemented, in which the packet header contains only the destination identification when it leaves the source. This information is sufficient for reaching the destination, not necessarily on the same route each time, and to overcome congrestion and failures. All these properties are implemented in a distributed manner. The system is asynchronous and designed for transmission of variable size packets.
This work applies microeconomic principles to the problem of load sharing in distributed computer systems. We consider a distributed system of processors connected in a possibly incomplete, point-to-point fashion. Job...
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This work applies microeconomic principles to the problem of load sharing in distributed computer systems. We consider a distributed system of processors connected in a possibly incomplete, point-to-point fashion. Jobs in the system compete for system resources in a distributed economy. We explore three extensions of previous work using this approach. In the first, we consider a fully connected network. The second is system heterogeneity, in particular different processor speeds. The third is the addition of a real-time element to the system, in which each job has a deadline. We study the performance of such systems by means of simulation programs written in the SIMSCRIPT simulation language. We compare the performance of these systems, and draw some conclusions about efficient implementation of microeconomic policies.
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