41,775 research outputs found
Scheduling multiple divisible loads on a linear processor network
Min, Veeravalli, and Barlas have recently proposed strategies to minimize the
overall execution time of one or several divisible loads on a heterogeneous
linear network, using one or more installments. We show on a very simple
example that their approach does not always produce a solution and that, when
it does, the solution is often suboptimal. We also show how to find an optimal
schedule for any instance, once the number of installments per load is given.
Then, we formally state that any optimal schedule has an infinite number of
installments under a linear cost model as the one assumed in the original
papers. Therefore, such a cost model cannot be used to design practical
multi-installment strategies. Finally, through extensive simulations we
confirmed that the best solution is always produced by the linear programming
approach, while solutions of the original papers can be far away from the
optimal
Inviwo -- A Visualization System with Usage Abstraction Levels
The complexity of today's visualization applications demands specific
visualization systems tailored for the development of these applications.
Frequently, such systems utilize levels of abstraction to improve the
application development process, for instance by providing a data flow network
editor. Unfortunately, these abstractions result in several issues, which need
to be circumvented through an abstraction-centered system design. Often, a high
level of abstraction hides low level details, which makes it difficult to
directly access the underlying computing platform, which would be important to
achieve an optimal performance. Therefore, we propose a layer structure
developed for modern and sustainable visualization systems allowing developers
to interact with all contained abstraction levels. We refer to this interaction
capabilities as usage abstraction levels, since we target application
developers with various levels of experience. We formulate the requirements for
such a system, derive the desired architecture, and present how the concepts
have been exemplary realized within the Inviwo visualization system.
Furthermore, we address several specific challenges that arise during the
realization of such a layered architecture, such as communication between
different computing platforms, performance centered encapsulation, as well as
layer-independent development by supporting cross layer documentation and
debugging capabilities
OpenCL + OpenSHMEM Hybrid Programming Model for the Adapteva Epiphany Architecture
There is interest in exploring hybrid OpenSHMEM + X programming models to
extend the applicability of the OpenSHMEM interface to more hardware
architectures. We present a hybrid OpenCL + OpenSHMEM programming model for
device-level programming for architectures like the Adapteva Epiphany many-core
RISC array processor. The Epiphany architecture comprises a 2D array of
low-power RISC cores with minimal uncore functionality connected by a 2D mesh
Network-on-Chip (NoC). The Epiphany architecture offers high computational
energy efficiency for integer and floating point calculations as well as
parallel scalability. The Epiphany-III is available as a coprocessor in
platforms that also utilize an ARM CPU host. OpenCL provides good functionality
for supporting a co-design programming model in which the host CPU offloads
parallel work to a coprocessor. However, the OpenCL memory model is
inconsistent with the Epiphany memory architecture and lacks support for
inter-core communication. We propose a hybrid programming model in which
OpenSHMEM provides a better solution by replacing the non-standard OpenCL
extensions introduced to achieve high performance with the Epiphany
architecture. We demonstrate the proposed programming model for matrix-matrix
multiplication based on Cannon's algorithm showing that the hybrid model
addresses the deficiencies of using OpenCL alone to achieve good benchmark
performance.Comment: 12 pages, 5 figures, OpenSHMEM 2016: Third workshop on OpenSHMEM and
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Advanced manned space flight simulation and training: An investigation of simulation host computer system concepts
The findings of a preliminary investigation by Southwest Research Institute (SwRI) in simulation host computer concepts is presented. It is designed to aid NASA in evaluating simulation technologies for use in spaceflight training. The focus of the investigation is on the next generation of space simulation systems that will be utilized in training personnel for Space Station Freedom operations. SwRI concludes that NASA should pursue a distributed simulation host computer system architecture for the Space Station Training Facility (SSTF) rather than a centralized mainframe based arrangement. A distributed system offers many advantages and is seen by SwRI as the only architecture that will allow NASA to achieve established functional goals and operational objectives over the life of the Space Station Freedom program. Several distributed, parallel computing systems are available today that offer real-time capabilities for time critical, man-in-the-loop simulation. These systems are flexible in terms of connectivity and configurability, and are easily scaled to meet increasing demands for more computing power
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