704070
Model-Guided Empirical Optimization for Multimedia Extension Architectures: A Case Study
Compiler technology for multimedia extensions must effectively utilize not only the SIMD compute engines but also the various levels of the memory hierarchy: superword registers, multi-level caches and TLB. In this paper, we describe a compiler that combines optimization across all levels of the memory hierarchy with automatic generation of SIMD code for multimedia extensions. At the high-level, model-guided empirical optimization is used to transform code to optimize for all levels of the memory hierarchy. This compiler interacts with a backend compiler exploiting superword-level parallelism that takes sequential code as input and produces SIMD code. This paper discusses how we have combined these technologies into a single framework. Through a case study with matrix multiply, we observe performance results that outperform the hand-tuned Intel MKL library, and achieve performance that is within 4% of the ATLAS self-tuning library with architectural defaults and more than 4X faster than the native Intel compiler.
596165
Combining models and guided empirical search to optimize for multiple levels of the memory hierarchy
This paper describes an algorithm for simultaneously optimizing across multiple levels of the memory hierarchy for dense-matrix computations. Our approach combines compiler models and heuristics with guided empirical search to take advantage of their complementary strengths. The models and heuristics limit the search to a small number of candidate implementations, and the empirical results provide the most accurate information to the compiler to select among candidates and tune optimization parameter values. We have developed an initial implementation and applied this approach to two case studies, matrix multiply and Jacobi relaxation. For matrix multiply, our results on two architectures, SGI R10000 and Sun UltraSparc IIe, outperform the native compiler, and either outperform or achieve comparable performance as the ATLAS self-tuning library and the hand-tuned vendor BLAS library. Jacobi results also substantially outperform the native compilers.
2976234
Spec-based repeater insertion and wire sizing for on-chip interconnect
Recently Lillis, et al. (see Proc. Custom Integrated Conf., p. 259-262, May 1995) presented an elegant dynamic programming approach to RC interconnect delay optimization through driver sizing, repeater insertion, and, wire sizing which employs the Elmore delay model for RC delay estimation and a crude repeater delay model. This approach, however, ignores an equally important aspect of interconnect optimization: transition time constraints at the sinks. More importantly, Elmore delay techniques because of their inherent inaccuracy are not suited to spec-based design which is directed towards synthesizing nets with user-specified delay/transition time requirements at the sinks. In this paper we present techniques for delay and transition time optimization for RC nets in the context of accurate moment-matching techniques for computing the RC delays and transition times, and an accurate driver/repeater delay model. The asymptotic increase in runtime over the Elmore delay model is O(q/sup 2/) where q is the order of the moment-matching approximation. Experiments on industrial nets indicate that this increase in runtime is acceptable. Our algorithm yields delay and transition time estimates within 5% of circuit simulation results.
14518854
Detecting and mapping thematic changes in transient networks
Research fronts are the forefront of a scientific field timely identifying emerging trends and abrupt changes in scientific literature is not only beneficial for users of digital libraries, but also instrumental for users to trace the movement of a research front. A research front can be seen as a dynamic and transient mapping from the state of the art to its immediate prior art - the intellectual base. Citation and co-citation analysis primarily focuses on the structure and dynamics of the intellectual base, information retrieval and related research mainly focuses on intrinsic properties of text documents. In this article, we describe a novel approach that enables us to detect and visualize the transient relationship over time. Temporal associations between content words connected to a surge of interest in scientific papers and high-impact articles in the intellectual base are identified and visualized as a time-variant network. We apply the approach to the detection of thematic changes over time in information visualization and research in terrorism.
18259111
An Empirical Study of Memory and Information Retrieval with a Spatial User Interface
The rapid advances in information retrieval, especially with visualisation-oriented user interface design, highlight the need for an understanding of the interplay between cognitive abilities of users and the design of visual user interfaces. In this study, we focus on two aspects of memory abilities of users in attempts to reveal their roles in facilitating information-seeking tasks. In particular, we study the relationships between associative memory and the use of a spatial user interface, and the relationship between visual memory and the same user interface. The design of the spatial user interface draws upon information visualisation techniques in order to highlight the strongest semantic relations in the search space. Two retrieval tasks were performed. While associative memory was strongly correlated with the first task, visual memory was negatively correlated with the second task. Both correlations were statistically significant. Implications for user interface design and suggestions for further empirical studies are also discussed.
9635823
Domain visualization for digital libraries
Domain visualization aims to reveal the most significant intellectual structure associated with a subject domain. This article illustrates how domain visualization enables novel ways of accessing scientific literature in digital libraries. The domain of computer graphics is visualized based on a citation analysis of articles appeared in the prestigious IEEE Computer Graphics and Applications over 18 years (1982-1999). The derived the high-dimensional domain structure is uncovered through the use of various visualization and animation techniques. Author co-citation maps open up new ways of visual information retrieval. Not only can users explore domain visualizations as a virtual landscape, but also invoke queries directly to a digital library. In this article, the domain visualization is linked to various citation-related information of scientific literature on the Web through NEC's ResearchIndex system.
43110
A study of self-adjusting quality of service control schemes
We report simulation methods and results for analyzing a self-adjusting quality of service (QoS) control scheme for multimedia/telecommunication systems based on resource reservation. We study the case in which high priority clients' QoS requirement is not changed throughout the service period, while low priority clients' QoS may be adjusted by the system between the maximum and minimum QoS levels specified in order to adapt to the load of the system. The goal of the system design is to optimize the system reward as a result of servicing clients with different QoS and reward/penalty requirements. A QoS manager in these systems can do a table lookup operation using the simulation result reported to optimize the system total reward dynamically in response to changing workloads during the run time. The simulation result is particularly applicable to multimedia and telecommunication systems in which dynamic QoS negotiation/renegotiation is used as a mechanism to optimize the overall system performance.