So-called worms, viruses, and Trojan horses that attack computer systems are defined. The vehicle that allows these attacks to occur, namely, the open computer internetwork, is examined. The problem ...of providing protection against attack in an internetwork environment is discussed. The need for professional responsibility on the part of the scientific and engineering community in enforcing strong ethical practices and neither tolerating nor condoning such practices is stressed.< >
The authors focus on techniques for enhancing the feasibility of using graphic visualization in analyzing the complexities of parallel software. The central drawback to applying such visual ...techniques is the overhead in developing analysis tools with flexible, customized views. The PARADISE system alleviates some of this design overhead by providing an abstract, object-oriented, visual modeling environment which expedites custom visual tool development. PARADISE is a visual tool which is used to develop other visual tools, or a meta-tool. The authors complement previous work on PARADISE by describing the philosophy behind its design, and how that philosophy leads to a methodology for constructing visual models which characterize parallel systems in general. The emphasis is on the crucial issues in utilizing visualization for parallel software development, and on how PARADISE deals with these issues.< >
Addresses the problem of creating software tools for visualizing the dynamic behavior of parallel applications and systems. PARADISE (PARallel Animated Debugging and Simulation Environment) ...approaches this problem by providing a meta-tool environment for generating custom visual analysis tools. PARADISE is a meta-tool because it is a tool which is utilized to create other tools. The authors focus on the user's view of the use of PARADISE for constructing tools which analyze the interaction between parallel systems and parallel applications. An example of its use, involving the PASM Parallel Processing System, is given.< >
The Seamless parallel system being developed at the University of Iowa ECE Department provides a method for providing latency tolerance in physically-distributed memory systems utilizing ...“off-the-shelf” RISC CPU's without incurring the overhead of multithreading. Seamless encompasses an evolutionary new programming model emphasizing data locality that views communication as data movement rather than message passing I/O. A hardware Locality Manager is added to each processing element to perform this data movement concurrently with computation.
Experimental analyses of an implementation of an SIMD algorithm for recursive digital filtering using the partitionable SIMD/MIMD (PASM) parallel processing system prototype at Purdue University are ...presented. The algorithm used easily generalizes to use N processing elements (PEs). Timing-based analyses are made based on a four-PE version by examining the following constituent execution times: microcontroller execution time, PE execution time, broadcast communication time, and the execution time of five additional phases in the recursive digital filtering summation calculation. Broadcast execution time was found to account for roughly 44% of the total execution time, and the implication of this is discussed for larger problem sizes and machine sizes. The total measured execution time is verified through summation of execution times for the various components of the algorithm.< >
Experimentation aimed at determining the potential benefit of mixed-mode SIMD/MIMD parallel architectures is reported. The experimentation is based on timing measurements made on the PASM system ...prototype at Purdue utilizing carefully coded synthetic variations of a well-known algorithm. The synthetic algorithms used to measure and evaluate this system were based on bitonic sorting of sequences stored in the processing elements. This computation was mapped to both the SIMD and MIMD modes of parallelism, as well as two hybrids of the SIMD and MIMD modes. The computations were coded in these four ways and experiments were performed that explore the trade-offs among them. The results of these experiments are presented and are discussed with special consideration of the effects of the system's architecture. The goal is to (as much as possible) obtain implementation independent analyses of the attributes of mixed-mode parallel processing with respect to the computational characteristics of the application being examined. The results are used to gain insight into the impact of computation mode on synchronization and data-conditional aspects of system performance.
As multiprocessor software solutions find their way into critical applications such as avionics as a means of increasing performance and reliability, the need for both debugging and testing tools ...increases dramatically. The authors focus on the gathering of accurate run-time information providing support for both debugging and testing of embedded multiprocessor systems by using run-time identification of simple events and postexecution identification of compound events. Additionally, they propose a way of combining specification-based (black-box) system testing and automatic monitoring to substantially reduce the complexity, tedium, and cost of complete structural (white-box) testing.< >
Experimentation aimed at determining the potential benefit of mixed-mode SIMD/MIMD (single instruction, multiple data/multiple instruction, multiple data) parallel architectures is reported. The ...experimentation is based on timing measurements made on the PASM (Partitionable SIMD/MIMD) system prototype utilizing carefully coded synthetic variations of a well-known algorithm. The synthetic algorithms used to measure and evaluate this system were based on bitonic sorting of sequences stored in the processing elements. This computation was mapped to both the hybrids of the SIMD and MIMD modes. The computations were coded in these four ways and experiments were performed that explore the tradeoffs among them. The results of these experiments are presented and discussed, with special consideration of the effects of the system's architecture. The goal is to obtain implementation-independent analyses of the attributes of mixed-mode parallel processing with respect to the computational characteristics of the application being examined.< >
This paper discusses the following: effective instrumentation as the key to effective monitoring; distributed monitoring systems as a basis for general purpose distributed multiprocessors; problems ...and prospects; performance monitoring, fact and fancy; and software aspects.< >
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