45488813
Parallel application performance on shared high performance reconfigurable computing resources
The use of a network of shared, heterogeneous workstations each harboring a reconfigurable computing (RC) system offers high performance users an inexpensive platform for a wide range of computationally demanding problems. However, effectively using the full potential of these systems can be challenging without the knowledge of the system's performance characteristics. While some performance models exist for shared, heterogeneous workstations, none thus far account for the addition of RC systems. Our analytic performance model includes the effects of the reconfigurable device, application load imbalance, background user load, basic message passing communication, and processor heterogeneity. The methodology proves to be accurate in characterizing these effects for applications running on shared, homogeneous, and heterogeneous HPRC resources. The model error in all cases was found to be less than 5% for application runtimes greater than 30s, and less than 15% for runtimes less than 30s.
7156330
Balancing FPGA Resource Utilities
Balancing the use of FGPA resources such as FPGA slices, block RAMs, and block multipliers is desirable in many FPGA applications. This task can be carried out manually by experienced hardware designers with the use of hardware description languages, such as Verilog and VHDL. However, many users of reconfigurable computers are software developers who depend on hardware synthesis tools or even high-level synthesis tools to deal with the details beneath the application logic. In this paper, a motivating example of balancing FPGA resource utilities is given first. A module selection optimization problem is then formulated, in which, balancing FPGA resource utilities is treated as a constraint, so that the solution to the module selection problem is the balanced use of the FPGA resources. Several variations of the problem formulation are discussed. A naive algorithm and an efficient greedy algorithm to solve the problem are provided and compared. Some experimental results are also presented.
52872904
Simulative analysis of dynamic scheduling heuristics for reconfigurable computing of parallel applications
The demand for processing power has been ever increasing with the growth of high-performance computing (HPC) applications and so have the constraints restricting the solutions to such requirements. High-performance distributed and parallel computing and custom-built, hardware-based computing have attempted to address this problem with some success but at a substantial cost. Recently, systems augmented with Field-Programmable Gate Arrays (FPGAs) offering a fusion of traditional parallel and distributed machines with customizable and dynamically reconfigurable hardware have emerged as a cost-effective alternative to traditional systems. However, providing a robust runtime environment for such systems to which HPC users have become accustomed has been fraught with numerous challenges. Dynamic scheduling of large-scale HPC applications in such parallel reconfigurable computing (RC) environments is one such challenge and has not been sufficiently studied to our knowledge. In this paper, we simulatively analyze the performance of several common HPC scheduling heuristics that can be used by an automated job management service to schedule application tasks on a parallel RC system. We also present a performance prediction model which the scheduling heuristics employ to schedule several common HPC applications on a collection of typical FPGA processing platforms.
7182268
Accelerating scientific applications with the SRC-6 reconfigurable computer: methodologies and analysis
Reconfigurable computing offers the promise of performing computations in hardware to increase performance and efficiency while retaining much of the flexibility of a software solution. Recently, the capacities of reconfigurable computing devices, like field programmable gate arrays, have risen to levels that make it possible to execute 64b floating-point operations. SRC Computers has designed the SRC-6 MAPstation to blend the benefits of commodity processors with the benefits of reconfigurable computing. In this paper, we describe our effort to accelerate the performance of several scientific applications on the SRC-6. We describe our methodology, analysis, and results. Our early evaluation demonstrates that the SRC-6 provides a unique software stack that is applicable to many scientific solutions and our experiments reveal the performance benefits of the system.
6340669
Phylospaces: reconstructing evolutionary trees in tuple space
Phylospaces is a novel framework for reconstructing evolutionary trees in tuple space, a distributed shared memory that permits processes to communicate and coordinate with each other. Our choice of tuple space as a concurrency model is somewhat unusual, given the prominence and success of pure message passing models, such as MPI. We use phylospaces to devise cooperative Rec-I-DCM3, a population-based strategy for navigating tree space. Cooperative Rec-I-DCM3 is based on Rec-I-DCM3, the fastest sequential algorithm under maximum parsimony. We compare the performance of the algorithms on two datasets consisting of 2,000 and 7,769 taxa, respectively. Our results demonstrate that cooperative Rec-I-DCM3 outperforms its sequential counterpart by at least an order of magnitude
10633849
Assessing differential usage of usenet social accounting meta-data
We describe a usage study of NetscanTech, a system that generates and publishes daily a range of social metrics across three dimensions: newsgroup, author, and thread, for a set of approximately 15,000 technical newsgroups in Usenet. We bring together three interlinked datasets: survey data, usage log data and social accounting data from Usenet participation, to triangulate the relationship between various user roles and differential usage of social metrics in NetscanTech. We found our most frequent users focused on information related to individual authors far more than any other information provided. In contrast, users that visited less frequently focused more on information related to newsgroups and viewing newsgroup metrics. Our results suggest features that designers and developers of online communities may wish to include in their interfaces to support the cultivation of different community roles.
840524
Newsgroup Crowds and AuthorLines: visualizing the activity of individuals in conversational cyberspaces
We discuss the design, implementation and evaluation of two related visualizations of authors' activities in Usenet newsgroups. Current Usenet news browsers focus on messages and thread structures while disregarding valuable information about the authors of messages and the participants of the various discussions. Newsgroup Crowds graphically represents the population of authors in a particular newsgroup. Authors are displayed according to the number of messages they contribute to each thread and the number of different days they appear in the space, illustrating and contrasting the interaction patterns of participants within the newsgroup. AuthorLines visualizes a particular author's posting activity across all newsgroups over a period of one year. This visualization reveals temporal patterns of thread initiation and reply that can broadly characterize the roles authors play in Usenet. We report the results of a user study that explored the value of these interfaces for developing high-level awareness of the activity and population in these conversational spaces. We suggest that interfaces that convey information about the social histories of populations and individuals may support better selection and evaluation of newsgroup content.
5238518
Evolving video skims into useful multimedia abstractions
This paper reports two studies that measured the effects of different “video skim” techniques on comprehension, navigation, and user satisfaction. Video skims are compact, content-rich abstractions of longer videos, condensations that preserve frame rate while greatly reducing viewing time. Their characteristics depend on the image- and audio-processing techniques used to create them. Results from the initial study helped refine video skims, which were then reassessed in the second experiment. Significant benefits were found for skims built from audio sequences meeting certain criteria.
7589048
Security considerations when designing a distributed file system using object storage devices
We present the design goals that led us to developing a distributed object-based secure file system, Brave. Brave uses mutually authenticated object storage devices, SCARED, to store file system data. Rather than require a new authentication infrastructure. we show how we use a simple authentication protocol that is bridged into existing security infrastructures, even if there is more than one authentication protocol or domain present. We position our work in the context of some of the current work going on in distributed secure file systems and present our implementation of our file system. We also present some security weaknesses that are shared with other distributed file systems that may not be apparent when designing these systems.