the author presents a comprehensive routing system for dispatching an object between action stops, finding the principals (on the basis of functional information), notifying them in turn when their action is required,...
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the author presents a comprehensive routing system for dispatching an object between action stops, finding the principals (on the basis of functional information), notifying them in turn when their action is required, and potentially relocating the routed object to their nodes. Additional mechanisms for nagging principles who forget to act on the object, reporting progress (or lack thereof) to other principles, handling routing exceptions, sharing action paths, and routing an object on a parallel path are discussed. the routing system is built as a generic service layer above object-support services. It is easy to use, flexible, and reliable.< >
the author proposes a filter component to be included in a load-sharing algorithm to detect short-lived jobs not worth considering for remote execution. three filters are presented. One filter, called History, detects...
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the author proposes a filter component to be included in a load-sharing algorithm to detect short-lived jobs not worth considering for remote execution. three filters are presented. One filter, called History, detects short-lived jobs by using job names and statistics based on previous executions. Job traces are allocated from diskless work stations connected by a local area network and supported by a distributed file system. Trace-driven simulation is then used to evaluate History with respect to the other filters. Two load-sharing algorithms show significant improvement of the mean job response ratio when the History filter is added.< >
Structure-oriented computer architecture is a research direction that tries to join the parallel processing facilities and decentralized control of multiprocessors or data-flow architectures withthe efficient memory ...
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Structure-oriented computer architecture is a research direction that tries to join the parallel processing facilities and decentralized control of multiprocessors or data-flow architectures withthe efficient memory access and pipelining techniques of data structure architectures. the main concepts and the motivation for introducing this term are shown. Data structure architectures are compared withthe successful concept of multiprocessors, and some limits of the latter are shown. the term structure-oriented computer architectures is introduced for a class of compound architectures built up from two rival architecture classes. Some effects of these architectures on software quality are discussed. An example of a proposed structure-oriented computer architecture is presented.< >
An introduction to the Axon architecture is presented. Axon is a host communication architecture for the distributed systems which can support interprocess communication with high throughput and low latency across a v...
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An introduction to the Axon architecture is presented. Axon is a host communication architecture for the distributed systems which can support interprocess communication with high throughput and low latency across a very high-speed internetwork. Network virtual storage (NVS) in the Axon host communication architecture for distributed applications is described. NVS extends segmented paged virtual storage management and address translation mechanisms to include segments located across an internetwork. this provides the ability to use efficiently the shared-memory paradigm in distributed systems for high-performance applications, such as scientific visualization and imaging.< >
this model is an extension of the Tantawi and Towsley (1985) single-job-class model as applied to a multiple-job-class model. Some properties of the optimal solution are shown. On the basis of these properties, a stra...
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this model is an extension of the Tantawi and Towsley (1985) single-job-class model as applied to a multiple-job-class model. Some properties of the optimal solution are shown. On the basis of these properties, a straightforward and efficient algorithm for optimal load balancing of multiclass jobs is derived. the performance of this algorithm is compared withthat of two other well-known algorithms for multiclass jobs, the flow deviation (FD) algorithm and the Dafermos algorithm. the authors' algorithm and the FD algorithm both require a comparable amount of storage that is far less than that required by the Dafermos algorithm. Numerical experiments show that for obtaining the optimal solution the authors' algorithm and the Dafermos algorithm require comparable computation times that are far less than that of the FD algorithm.< >
the authors define a causal distributed breakpoint, which is initiated by a sequential breakpoint in one process of a distributed computation and restores each process in the computation to its earliest state that ref...
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the authors define a causal distributed breakpoint, which is initiated by a sequential breakpoint in one process of a distributed computation and restores each process in the computation to its earliest state that reflects all events that happened before the breakpoint. An algorithm for finding the causal distributed breakpoint, given a sequential breakpoint in one of the processes, is presented. Approximately consistent checkpoint sets are used for efficiently restoring each process to its state in a causal distributed breakpoint. Causal distributed breakpoints assume deterministic processes that communicate solely by messages. the dependencies that arise from communication between processes are logged. Dependency logging and approximately consistent checkpoint sets are implemented on a network of SUN workstations running the V-System. Overhead on the message-passing primitives varies between 1% and 14% for dependency logging. Execution time overhead for a 200*200 Gaussian elimination is less than 4% and generates a dependency log of 288 kbytes.< >
the use of weakly consistent memories in distributed shared memory systems to combat unacceptable network delay and to allow such systems to scale is proposed. Proposed memory correctness conditions are surveyed, and ...
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the use of weakly consistent memories in distributed shared memory systems to combat unacceptable network delay and to allow such systems to scale is proposed. Proposed memory correctness conditions are surveyed, and how they are related by a weakness hierarchy is demonstrated. Multiversion and messaging interpretations of memory are introduced as means of systematically exploring the space of possible memories. Slow memory is presented as a memory that allows the effects of writes to propagate slowly through the system, eliminating the need for costly consistency maintenance protocols that limit concurrency. Slow memory processes a valuable locality property and supports a reduction from traditional atomic memory. thus slow memory is as expressive as atomic memory. this expressiveness is demonstrated by two exclusion algorithms and a solution to M.J. Fischer and A. Michael's (1982) dictionary problem on slow memory.< >
the authors present a general methodology for bounding the range of sequence numbers utilized in a distributed program to order events. this methodology requires explicit knowledge of bounds on the rate at which proce...
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the authors present a general methodology for bounding the range of sequence numbers utilized in a distributed program to order events. this methodology requires explicit knowledge of bounds on the rate at which processes may increment sequence numbers and the time required to transmit a message. It may also require the inclusion of additional synchronization in a distributed application which utilizes the bounded sequence numbers. the methodology is demonstrated in three contexts. It is shown how a scheme for bounding sequence numbers on requests for network mutual exclusion is consistent withthe methodology. Sequence numbers are bound in a network mutual exclusion protocol. the methodology is utilized to bound the size of sequence numbers used in successive fault-tolerant broadcasts among a group of fail-stop processors. In all three cases, with totally different message-passing patterns and means of incrementing sequence numbers, consistent application of the methodology is stressed.< >
A combination of join and semijoin operations is applied to minimize the communication cost for distributed query processing. A formula is developed to estimate the cardinality of a relation resulting from join operat...
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A combination of join and semijoin operations is applied to minimize the communication cost for distributed query processing. A formula is developed to estimate the cardinality of a relation resulting from join operations specified by a query graph. Two important concepts which occur withthe use of join operations as reducers in query processing are studied and exploited, namely, gainful semijoins and pure join attributes. Some semijoins, though not profitable themselves, may benefit from the execution of subsequent joint operations and become profitable owing to the use of join operations as reducers. Such a semijoin is termed a gainful semijoin. Also, join attributes which are not part of the output attributes are referred to as pure join attributes. A formula to estimate the cardinality of a relation resulting from a projection operation is derived. the results show the attractiveness of the approach of applying a combination of joins and semijoins as reducers to distributed query processing.< >
Interconnection structures that can provide access to multiple levels of a shared memory hierarchy in a multiprocessor are investigated. the results are also applicable to distributed memory architectures in which loc...
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Interconnection structures that can provide access to multiple levels of a shared memory hierarchy in a multiprocessor are investigated. the results are also applicable to distributed memory architectures in which localities of communication can be statically defined. All the structures presented conform in some fashion to the binary cube topology with per-processor logic cost ranging from O(log N) to O(log/sup 2/N). the results illustrate that without resorting to separate networks for access at each level, several architectures can provide fast access at lower levels in the hierarchy and progressively slower access at higher levels. Even at the highest communication level (corresponding to system wide communication), messages encounter less delay than in a nonhierarchical access situation.< >
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