摘要:

AbstractPetri nets are proposed as a general‐purpose design and modelling tool for parallel programs. The advantages of Petri nets for this purpose are discussed, and a solution to the Dining Philosophers problem is developed using simple Place‐Transition nets. The limitations of Place‐Transition nets are described, and the Dining Philosophers problem is used to illustrate how Coloured Petri nets can overcome these limitations. A more complex example of a Coloured Petri net is then given, and it is shown how a collection of processes in the Occam programming language can be developed directly from the properties of the net. Another Petri net model of a simple process farm is given, and a solution is developed in Parallel C: this further highlights the suitability of Petri nets as a design tool for parallel pro

ISSN:1040-3108    

DOI:10.1002/cpe.4330050202

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWe report significant speed‐up for seismic migration running in parallel on networkconnected IBM RISC/6000 workstations, A sustained performance of 15 MFLOP is obtained on a single‐entry‐level model 320, and speed‐ups as high as 5 are obtained for six workstations connected by Ethernet or token ring. Our parallel software uses remote procedure calls provided by NCS (Network Computing System). We have run over a dozen workstations in parallel, but speed‐ups become limited by network data rate. Fiber‐optic communication should allow much greater speed‐ups, and we describe our preliminary results with the fiberoptic serial link adapter of the RISC/6000. We also present a simple theoretical model that agrees well with our measurements and allows speed‐up to be predicted from a knowledge of the ratio of computation to communication, which can be determined empirically before the program is parallellzed. We conclude with a brief discussion of alternative software approaches and programming models for network‐connected parallel systems. In particular, our program was recently ported to PVM and Linda, and preliminary measurements yield speed‐ups very close to t

ISSN:1040-3108    

DOI:10.1002/cpe.4330050203

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe transputer is one of the most cost‐effective multicomputer components to buy, but still one of the hardest to program. Even if the parts of a program that are destined for individual transputers are programmed in a familiar high‐level language (Ada or Fortran or C), users are forced to be aware of occam when connecting transputers together with harnesses. Moreover, the design of parallel and distributed algorithms is in itself a challenging field. This paper describes experience with using the Alsys Ada compiler on single and multiple transputer configurations, and considers whether Ada makes it any easier to gain access to the power of multi‐transputers. Early performance figures indicate that Ada running on transputer arrays compares favourably with the speed of other languages. An assessment of the impact of the proposed Ada 9X support for distribution is

ISSN:1040-3108    

DOI:10.1002/cpe.4330050204

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA solution is proposed to the problem of interactive visualization and rendering of volume data. Designed for parallel distributed memory MIMD architectures, the volume rendering system is based on the ray tracing (RT) visualization technique, the Sticks representation scheme (a data structure exploiting data coherence for the compression of classified data sets), the use of a slice‐partitioning technique for the distribution of the data between the processing nodes and the consequent ray‐data‐flow parallelizing strategy.The system has been implemented on two different architectures: an inmos Transputer network and a hypercube nCUBE 6400 architecture. The high number of processors of this latter machine has allowed us to exploit a second level of parallelism (parallelism on image space, or parallelism on pixels) in order to arrive at a higher degree of scalability. In both proposals, the similarities between the chosen data‐partitioning strategy, the communications pattern of the visualization processes and the topology of the physical system architecture represent the key points and provide improved software design and efficiency. Moreover, the partitioning strategy used and the network interconnection topology reduce the communications overhead and allow for an efficient implementation of a static load‐balancing technique based on the prerendering of a low resolution image.Details of the practical issues involved in the parallelization process of volumetric RT, commonly encountered problems (i.e. termination and deadlock prevention) and the sw migration process between different architectures are

ISSN:1040-3108    

DOI:10.1002/cpe.4330050205

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1040-3108    

DOI:10.1002/cpe.4330050201

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY