1,720,986 research outputs found
Characterization of the evolution a news Web site
No full textThe Web has become a ubiquitous tool for distributing knowledge and information and for conducting businesses. To exploit the huge potential of the Web as a global information repository, it is necessary to understand its dynamics. These issues are particularly important for news Web sites as they are expected to provide fresh information on current world events to a potentially large user population. This paper presents an experimental study aimed at characterizing and modeling the evolution of a news Web site. We focused on the MSNBC Web site as it is a good representative of its category in terms of structure, news coverage and popularity. Specifically, we analyzed how often and to what extent the content of this site changed and we identified models describing its dynamics. The study has shown that the rate of page creations and updates was characterized by some well defined patterns that varied as a function of time of day and day of week. On the contrary, the content of individual pages changed to a different extent. Most updates involved a very small fraction of their content, whereas very few were more extensive and spread over the whole page. By taking into accounts all these aspects, we derived analytical models able to accurately capture and reproduce the evolution of the news Web site
A Methodology Towards Automatic Performance Analysis of Parallel Applications
No full textTuning and debugging the performance of parallel applications is an iterative process consisting of several steps dealing with identification and localization of inefficiencies, repair, and verification of the achieved performance. In this paper, we address the analysis of the performance of parallel applications from a methodological viewpoint with the aim of identifying and localizing inefficiencies. Our methodology is based on performance metrics and criteria that highlight the properties of the applications and the load imbalance and dissimilarities in the behavior of the processors. A few case studies illustrate the application of the methodology
Redistribution strategies for portable parallel FFT: a case study
No full textThe best approach to parallelize multidimensional FFT algorithms has long been under debate, Distributed transposes are widely used, but they also vary in communication policies and hence performance. In this work we analyze the impact of different redistribution strategies on the performance of parallel FFT, on various machine architectures. We found that some redistribution strategies were consistently superior, while some others were unexpectedly inferior, An in-depth investigation into the reasons for this behavior is included in this work. Copyright (C) 2001 John Wiley & Sons, Ltd
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