Interactive program steering is a promising technique for improving the performance of parallel and distributed applications. Steering decisions are typically based on visual presentations of some subset of the comput...
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ISBN:
(纸本)0818677937
Interactive program steering is a promising technique for improving the performance of parallel and distributed applications. Steering decisions are typically based on visual presentations of some subset of the computation's current state, a historical view of the computation's behavior, or views of metrics based on the program's performance. As in any endeavor good decisions require accurate information. However the distributed nature of the collection process may result in distortions in the portrayal of the program's execution. These distortions stem from the merging of streams of information from distributed collection points into a single stream without enforcing the ordering relationships that held among the program components that produced the information. An ordering filter placed at the point at which the streams are merged can ensure a valid ordering, leading to more accurate visualizations and better informed steering decisions. In this paper we describe the implementation of such filters in the Falcon interactive steering toolkit, and present a methodology for their specification for automated generation.
Symbolic computing is one of fastest growing areas of scientific computing. An overview of the state-of-the-art in symbolic computations on distributed architectures, in particular Web and Grid architectures, is prese...
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ISBN:
(纸本)9780769529172
Symbolic computing is one of fastest growing areas of scientific computing. An overview of the state-of-the-art in symbolic computations on distributed architectures, in particular Web and Grid architectures, is presented. The background information, including typical application areas, is followed by a list of past and on-going projects involving symbolic computations on distributed computing environments. To illustrate in more details issues involved in porting computer algebra systems to the Grid, some case studies involving popular environments are presented.
Encrypted databasessystems and searchable encryption schemes still leak critical information (e.g.: access patterns) and require a choice between privacy and efficiency. We show that using ORAM schemes as a black-box...
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ISBN:
(纸本)9781665438193
Encrypted databasessystems and searchable encryption schemes still leak critical information (e.g.: access patterns) and require a choice between privacy and efficiency. We show that using ORAM schemes as a black-box is not a panacea and that optimizations are still possible by improving the data structures. We design an ORAM-based secure database that is built from the ground up: we replicate the typical data structure of a database system using different optimized ORAM constructions and derive a new solution for oblivious searches on databases. Our construction has a lower bandwidth overhead than state-of-the-art ORAM constructions by moving client-side computations to a proxy with an intermediate (rigorously defined) level of trust, instantiated as a server-side isolated execution environment. We formally prove the security of our construction and show that its access patterns depend only on public information. We also provide an implementation compatible with SQL databases (PostgresSQL). Our system is 1.2 times to 4 times faster than state-of-the-art ORAM-based solutions.
Vector prefix and reduction are collective communication primitives in which all processors must cooperate. We present two parallel algorithms, the direct algorithm and the split algorithm, for vector prefix and reduc...
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ISBN:
(纸本)0818684038
Vector prefix and reduction are collective communication primitives in which all processors must cooperate. We present two parallel algorithms, the direct algorithm and the split algorithm, for vector prefix and reduction computation on coarse-grained, distributed-memory parallel machines. Our algorithms are relatively architecture independent and can be used effectively in many applications such as Pack/Unpack, Array Prefix/Reduction Functions, and Array Combining Scatter Functions, which are defined in Fortran 90 and in High Performance Fortran. Experimental results on the CM-5 are presented.
In this note, the method given in [13] is extended to a certain distributed parameter systems to check the stability of the convex combinations of the irrational polynomials. Illustrative examples are included.
ISBN:
(纸本)0780312813
In this note, the method given in [13] is extended to a certain distributed parameter systems to check the stability of the convex combinations of the irrational polynomials. Illustrative examples are included.
New biological experimental techniques are continuing to generate large amounts of data using DNA, RNA, human genome and protein sequences. The quantity and quality of data from these experiments makes analyses of the...
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ISBN:
(纸本)0769522815
New biological experimental techniques are continuing to generate large amounts of data using DNA, RNA, human genome and protein sequences. The quantity and quality of data from these experiments makes analyses of their results very time-consuming, expensive and impractical. Searching on DNA and protein databases using sequence comparison algorithms has become one of the most powerful techniques to better understand the functionality of particular DNA, RNA, genome, or protein sequence. This paper presents a technique to effectively combine fine and coarse grain parallelism using general purpose processors for sequence homology database searches. The results show that the classic Smith-Waterman sequence alignment algorithm achieves super linear performance with proper scheduling and multi-level parallel computing at no additional cost.
Most work on database integration has considered only support for data retrieval, not support for updates, and often the use for a special semantically rich data model has been required. The authors present an approac...
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ISBN:
(纸本)0818608935
Most work on database integration has considered only support for data retrieval, not support for updates, and often the use for a special semantically rich data model has been required. The authors present an approach to database integration which supports updates and which uses only the standard relational data model. Many of the ideas used in this approach are applicable to database integration in the context of other data models as well.
The following topics are dealt with: access methods;distributed operating systems and databases;database design and implementation;performance evaluation;architectural support for database management;evaluating recurs...
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ISBN:
(纸本)0818607629
The following topics are dealt with: access methods;distributed operating systems and databases;database design and implementation;performance evaluation;architectural support for database management;evaluating recursive queries;file structures;parallel processing database systems;object-based systems;performance in distributedsystems;improving concurrency in distributedsystems;fault tolerance and correctness;knowledge representation;resiliency in distributedsystems;fault-tolerant storage systems;data modeling;historical databases;extending the relational model;CAD/CAM systems;and query processing. 85 papers are published in the present proceedings.
Cyber-physical systems (CPS) are computer systems with integrated software and physical components that ideally seamlessly interact with the real world and each other. While the use of distributed CPS has rapidly grow...
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ISBN:
(纸本)9781665438193
Cyber-physical systems (CPS) are computer systems with integrated software and physical components that ideally seamlessly interact with the real world and each other. While the use of distributed CPS has rapidly grown over the past decade, so has the need for developing efficient methods to ascertain reliability of these systems by validating their correctness. Since exhaustively validating correctness of a distributed CPS is usually not feasible nor possible, many modern validation methods involve run-time verification of distributed CPS based on safety properties. Our work focuses on developing time and resource efficient assurance techniques that can run in parallel with the execution of these systems to ensure reliability.
Heterogeneity is becoming quite common in distributedparallel computing systems, both in processor architectures and in communication networks. Different types of networks have different performance characteristics, ...
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ISBN:
(纸本)0818681187
Heterogeneity is becoming quite common in distributedparallel computing systems, both in processor architectures and in communication networks. Different types of networks have different performance characteristics, while different types of messages may have different communication requirements. In this work, we analyze two techniques for exploiting these heterogeneous characteristics and requirements to reduce the communication overhead of parallel application programs executed an distributed computing systems. The performance based path selection (PBPS) technique selects the best (lowest latency) network among several for each individual message, while the second technique aggregates multiple networks into a single virtual network. We present a general approach for applying and evaluating these techniques to a distributed computing system with multiple interprocessor communication networks, We also generate performance curves for a cluster of IBM workstations interconnected with Ethernet, ATM, and Fibre Channel networks. As we show with several of the NAS benchmarks, these curves can be used to estimate the potential improvement in communication performance that can be obtained with these: techniques, given some simple communication characteristics of an application program.
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