共查询到20条相似文献,搜索用时 15 毫秒
1.
Jake Cobb Author Vitae Author Vitae 《Journal of Systems and Software》2008,81(9):1539-1558
Web proxy caches are used to reduce the strain of contemporary web traffic on web servers and network bandwidth providers. In this research, a novel approach to web proxy cache replacement which utilizes neural networks for replacement decisions is developed and analyzed. Neural networks are trained to classify cacheable objects from real world data sets using information known to be important in web proxy caching, such as frequency and recency. Correct classification ratios between 0.85 and 0.88 are obtained both for data used for training and data not used for training. Our approach is compared with Least Recently Used (LRU), Least Frequently Used (LFU) and the optimal case which always rates an object with the number of future requests. Performance is evaluated in simulation for various neural network structures and cache conditions. The final neural networks achieve hit rates that are 86.60% of the optimal in the worst case and 100% of the optimal in the best case. Byte-hit rates are 93.36% of the optimal in the worst case and 99.92% of the optimal in the best case. We examine the input-to-output mappings of individual neural networks and analyze the resulting caching strategy with respect to specific cache conditions. 相似文献
2.
In this paper, Web cache optimization by utilizing syntactic features extracted from cache objects is studied. A nonlinear model is used to predict the value of each cache object by using features from the HTTP responses of the server, the access log of the cache, and from the HTML structure of the object. In a case study, linear and nonlinear models are used to classify about 50,000 HTML documents according to their popularity. The nonlinear model yields classification percentages of 64 and 74 for the documents to be stored or to be removed from the cache, respectively. A synthetic workload is then used to study the performance gain from the classifier in a conventional Least Recently Used cache model. The results suggest that the proposed approach can improve the performance of the cache substantially. 相似文献
3.
Many geographically distributed proxies are increasingly used for collaborative Web caching to improve performance. In hashing-based collaborative Web caching, the response times can be negatively impacted for those URL requests hashed into geographically distant or overloaded proxies. In this paper, we present and evaluate a latency-sensitive hashing scheme for collaborative Web caching. It takes into account latency delays due to both geographical distances and dynamic load conditions. Each URL request is first hashed into an anchor hash bucket, with each bucket mapping to one of the proxies. Secondly, a number of nearby hash buckets are examined to select the proxy with the smallest latency delay to the browser. Trace-driven simulations are conducted to evaluate the performance of this new latency-sensitive hashing. The results show that (1) with the presence of load imbalance due to skew in request origination or hot-spot references, latency-sensitive hashing effectively balances the load by hashing into geographically distributed proxies for collaborative Web caching, and (2) when the overall system is lightly loaded, latency-sensitive hashing effectively reduces latency delays by directing requests to geographically closer proxies. 相似文献
4.
Timing predictability of cache replacement policies 总被引:1,自引:0,他引:1
Hard real-time systems must obey strict timing constraints. Therefore, one needs to derive guarantees on the worst-case execution
times of a system’s tasks. In this context, predictable behavior of system components is crucial for the derivation of tight
and thus useful bounds. This paper presents results about the predictability of common cache replacement policies. To this
end, we introduce three metrics, evict, fill, and mls that capture aspects of cache-state predictability. A thorough analysis of the LRU, FIFO, MRU, and PLRU policies yields the
respective values under these metrics. To the best of our knowledge, this work presents the first quantitative, analytical
results for the predictability of replacement policies. Our results support empirical evidence in static cache analysis.
相似文献
Reinhard WilhelmEmail: |
5.
代理缓存一致性策略和替换策略的研究 总被引:5,自引:1,他引:5
针对代理缓存的一致性策略和替换策略还没有很好地结合起来,从而影响了代理缓存系统的整体性能的现状,分别探讨了基于Internet的代理缓存一致性策略和替换策略的处理流程、性能评价指标和研究现状,进而给出将这两种策略结合起来的一致性一替换算法的处理流程,并提出陈旧命中比是其主要性能评价指标,能很好地衡量代理缓存的各种算法的优劣和代理缓存系统的整体性能。 相似文献
6.
This paper examines a novel cache management policy applied to non-collaborative and collaborative environments of more than one proxy server that serve homogeneous or even heterogeneous client requests for video streaming over the Internet. This cache management policy, which we call LRLFU because of a combination between an LRU and an LFU policy, is capable of capturing the changing popularities of the various videos by attaching a caching value to every video according to how recently and how frequently the video was requested, and decides to cache the most ‘valuable’ videos. Our event-driven simulations have shown that LRLFU when applied to a simple non-collaborative topology of proxies and compared with previous work in this area (1) improve the byte-hit ratio (BHR), (2) significantly reduce the fraction of user requests with delayed starts and (3) require less CPU overhead. Furthermore, our simulation results have shown that the collaborative hierarchical tree topology of proxies that we examine achieves a much higher BHR when using the same overall cache capacity with the simple topology and in general provides better performance characteristics.This work was conducted while A. Satsiou was a MSc student in the Department of Electronic and Computer Engineering Technical University of Crete. 相似文献
7.
Yong H Shin 《Information Processing Letters》2004,91(5):227-232
A new Web cache sharing scheme is presented. Our scheme reduces the duplicated copies of the same objects in global shared Web caches. It also reduces the message overhead of existing schemes significantly. Trace-driven simulations with actual Web cache logs show that the proposed scheme performs better than the two well-known Web cache sharing schemes, the Internet Cache Protocol and the Cache Array Routing Protocol. 相似文献
8.
Web prefetching is an attractive solution to reduce the network resources consumed by Web services as well as the access latencies perceived by Web users. Unlike Web caching, which exploits the temporal locality, Web prefetching utilizes the spatial locality of Web objects. Specifically, Web prefetching fetches objects that are likely to be accessed in the near future and stores them in advance. In this context, a sophisticated combination of these two techniques may cause significant improvements on the performance of the Web infrastructure. Considering that there have been several caching policies proposed in the past, the challenge is to extend them by using data mining techniques. In this paper, we present a clustering-based prefetching scheme where a graph-based clustering algorithm identifies clusters of “correlated” Web pages based on the users’ access patterns. This scheme can be integrated easily into a Web proxy server, improving its performance. Through a simulation environment, using a real data set, we show that the proposed integrated framework is robust and effective in improving the performance of the Web caching environment. 相似文献
9.
Web caches are traditionally organised in a simple tree like hierarchy. In this paper, a new architecture is proposed, where federations of caches are distributed globally, caching data partially. The advantages of the proposed system are that contention on global caches is reduced, while at the same time improving the scalability of the system since extra cache resources can be added on the fly. Among other topics discussed in this papers, is the scalability of the proposed system, the algorithms used to control the federation of Web caches and the approach used to identify the potential Web cache partners. In order to obtain a successful collaborative Web caching system, the formation of federations must be controlled by an algorithm that takes the dynamics of the Internet traffic into consideration. We use the history of Web cache access in order to determine how federations should be formed. Initial performance results of a simulation of a number of nodes are promising. 相似文献
10.
Web 2.0 systems are more unpredictable and customizable than traditional web applications. This causes that performance techniques, such as web caching, limit their improvements. Our study was based on the hypotheses that the use of web caching in Web 2.0 applications, particularly in content aggregation systems, can be improved by adapting the content fragment designs. We proposed to base this adaptation on the analysis of the characterization parameters of the content elements and on the creation of a classification algorithm. This algorithm was deployed with decision trees, created in an off-line knowledge discovery process. We also defined a framework to create and adapt fragments of the web documents to reduce the user-perceived latency in web caches. The experiment results showed that our solution had a remarkable reduction in the user-perceived latency even losses in the cache hit ratios and in the overhead generated on the system, in comparison with other web cache schemes. 相似文献
11.
本地缓存和代理服务器环境下的网络日志挖掘 总被引:5,自引:0,他引:5
介绍了网络日志挖掘的基本概念,提出了一个网络日志挖掘通用系统的结构,分析了本地缓存和代理服务器对日志挖掘的影响,并给出了一种近似解决方案。这种方案通过网络拓扑结构和日志文件记录的结合,将杂乱无章的日志记录组合成具有语义信息的事务记录,从而使挖掘结果更有意义。 相似文献
12.
代理Web Cache性能分析 总被引:3,自引:0,他引:3
采用WebCache技术提高当前Internet性能已成为一个主流的研究领域,其功能原理就象处理器和文件系统中的多级高速缓存一样。大规模Web高速缓存系统已成为许多国家Internet基础设施的重要组成部分。该文从三个不同访问规模的代理WebCache的跟踪日志出发,分析了WebCache的用户访问模式、Cache命中率、Cache服务器处理延迟等统计特征,提出基于分布式共享RAM和外存储结合的两级协同WebCache集群技术,可以提供可扩展的高性能并行Web高速缓存服务。 相似文献
13.
王春娟 《数字社区&智能家居》2008,(3)
在Internet快速发展的今天,用户通过网络获取大量的信息,各种各样的Web应用系统也随之产生,用户对Web应用系统的响应速度上升到最高需求。为提高用户的感受并降低企业和服务提供者的成本,经过研究和分析,发现缓存技术是在不增加成本的前提下提高Web应用系统性能的最有效的解决方案之一。 相似文献
14.
In this paper, we propose a novel approach to enhancing web proxy caching, an approach that integrates content management
with performance tuning techniques. We first develop a hierarchical model for management of web data, which consists of physical
pages, logical pages and topics corresponding to different abstraction levels. Content management based on this model enables
active utilization of the cached web contents. By defining priority on each abstraction level, the cache manager can make
replacement decisions on topics, logical pages, and physical pages hierarchically. As a result, a cache can always keep the
most relevant, popular, and high-quality content. To verify the proposed approach, we have designed a content-aware replacement
algorithm, LRU-SP+. We evaluate the algorithm through preliminary experiments. The results show that content management can
achieve 30% improvement of caching performance in terms of hit ratios and profit ratios (considering significance of topics)
compared to content-blind schemes.
Received 19 March 2001 / Revised 17 April 2001 / Accepted in revised form 25 May 2001 相似文献
15.
16.
17.
18.
集中管理式Web缓存系统及性能分析 总被引:5,自引:0,他引:5
共享缓存文件是减少网络通信量和服务器负载的重要方法,本文在介绍Web Caching技术及流行的Web缓存通信协议ICP的基础上,提出了一种集中管理式Web缓存系统,该系统通过将用户的HTTP请求,按照一定的算法分发到系统中某一合适的缓存服务器上,从而消除了缓存系统内部服务器之间庞大的通信开销及缓存处理负担,减少了缓存内容的冗余度.通过分析,证明了集中管理式Web缓存系统比基于ICP的简单缓存系统具有缓存效率高、处理开销低、延迟小等优点,并且该系统具有良好的可扩展性. 相似文献
19.
一种基于Web挖掘的网站性能评价方法 总被引:10,自引:0,他引:10
文章分析了影响网站性能的各种因素,建立了评价网站性能的指标体系,提出了一种基于Web日志挖掘的评价网站性能的方法,有效地解决了网站性能的评价问题。 相似文献
20.
该文论述HTTP协议的主要特性,分析了TCP和HTTP的传输过程,阐述了HTTP与TCP影响Web服务器性能的原因,分析了各种网络特性对Web服务器性能的影响和影响Web服务器性能的主要因素,最后提出了优化WWW系统性能的主要方法。 相似文献