PCI协议对Cache的支持

论述了Ｃａｃｈｅ在高性能计算机系统中的作用和访问Ｃａｃｈｅ的过程，以及Ｃａｃｈｅ数据一致性问题和解决的方法，介绍和分析了ＰＣＩ协议对Ｃａｃｈｅ的支持。     

Cache一致性协议的研究与评价

Ｃａｃｈｅ一致性是紧耦合多处理机系统设计中的一项重要课题．为提高访存效率，每台处理机通常带有高速缓冲存储器Ｃａｃｈｅ。这便产生了Ｃａｃｈｅ一致性问题，要求共享数据在各Ｃａｃｈｅ间以及Ｃａｃｈｅ与主存间保持一致。为此出现了多种Ｃａｃｈｅ一致性协议。本文分析了几种类型的一致性协议，并对其进行了软件模拟和性能评价．     

RISC工作站的Cache设计

Ｃａｃｈｅ技术是改善计算机系统性能的最重要和最有效的手段之一。近年来兴起的ＲＩＳＣ结构更扩大了Ｃａｃｈｅ技术应用领域。在ＲＩＳＣ系统中，整机性能与处理器对内存的有效访问直接相关，从而使得Ｃａｃｈｅ也更为重要。本文对ＲＩＳＣ系统Ｃａｃｈｅ设计中的许多问题进行讨论，并给出华胜４０００系列ＲＩＳＣ工作站的Ｃａｃｈｅ设计作为实例。     

Cacheman—加速你的Windows

你想加速你的Ｗｉｎｄｏｗｓ吗？ Ｃａｃｈｅ－ｍａｎ能够帮到你。它是一个用于优化Ｗｉｎｄｏｗｓ缓存设置的工具,可以让你方便快捷地设置Ｃａｃｈｅ中的某些参数,分别对 Ｄｉｓｋ Ｃａｃｈｅ（磁盘缓存）和 ＦｉｌｅＣａｃｈｅ（文件缓存）进行优化,并可以对不同的使用环境进行不同的优化设置,使之最大限度地发挥自己的威力,从而有效地提高系统的运行速度。 Ｃａｃｈｅｍａｎ的界面做得非常体贴用户。如图１所示,我们可以在该窗口的上半部分看到系统当前的内存使用状况,包括物理内存（Ｐｈｙｓｉｃａｌ ｍｅｍｏｒｙ）和虚拟内存（…     

廉价冗余磁盘阵列（RAID）Cache浅析

廉介冗余磁盘陈列技术已掀起研究开发热潮，磁盘Ｃａｃｈｅ技术的研究早在七十年代就已广泛展开，但是关于磁盘阵列Ｃａｃｈｅ技术的专门性研究文献在国内外并不多见。本文论述了磁盘阵列中引入高速缓存Ｃａｃｈｅ的必要性，综述了磁盘阵列Ｃａｃｈｅ技术的国内外技术动态，提出了磁盘阵列Ｃａｃｈｅ研究中的几个关键问题，并阐述了作者的观点。     

Cache代理:一种改进WWW性能的协议机制

ＷｏｒｌｄＷｉｄｅＷｅｂ等全球范围的分布式信息系统的使用日益广泛，占用了Ｉｎｔｅｒｎｅｔ上很大一部分可用带宽，服务器负载繁重，网络延迟难以满足用户需求。Ｃａｃｈｅ代理机制不但可显著减少响应时间，对服务器负载分流及降低网络带宽占用也有重要影响。本文分析了ＷＷＷ信息服务的访问特性和Ｃａｃｈｅ代理的有效性，给出分布式信息系统传输协议应用层Ｃａｃｈｅ协议的工作机理和一致性维护模型（过期模型和验证模型），讨论了Ｃａｃｈｅ代理同服务器的协同工作方式。     

Pentium的Cache组织结构及其在多机系统中的一致性机制

本文对Ｐｅｎｔｉｕｍ的片内Ｃａｃｈｅ工作机理进行分析和研究，由此得到与Ｃａｃｈｅ系统设计有关的Ｐｅｎｔｉｕｍ芯片的引脚信号，通过分析这些引脚信号的作用为设计Ｃａｃｈｅ系统提供了参考和依据     

WWW代理技术现状与改进方案

客户机Ｃａｃｈｅ技术、ＷＷＷ上的代理技术、公共Ｃａｃｈｅ技术,指出了它们各自的局限性。提出了一种改进方案─—ＷＷＷ本地代理的公共Ｃａｃｈｅ和辅助代理相结合的解决方案。     

Intel Itamium处理器的Cache

Ｉｎｔｅｌ最近更新了关于第一款ＩＡ－６４体系微架构的Ｉｔａｎｉｕｍ处理器的新特点,这款６４ｂｉｔ　Ｉｔａｎｉｕｍ处理器采用有限的Ｌ２－Ｃａｃｈｅ,只有９６ＫＢ,双Ｌ１－Ｃａｃｈｅ将分别为１６ＫＢ,另外,Ｉｔａｎｉｕｍ还拥有一个非常快的１２８位结构Ｌ３－Ｃａｃｈｅ,容量可达２－４ＭＢ,而Ｉｔａｎｉｕｍ的升级版本ＭｃＫｉｎｌｅｙ则拥有更大的Ｌ１和Ｌ２－Ｃａｃｈｅ。 下面是ＩｔａｎｉｕｍＣａｃｈｅ的细节情况： Ｌ１－Ｃａｃｈｅ容量为１６Ｋｂｙｔｅ,采用３２ｂｙｔｅ管线４路（４－ｗａｙ）联合指令; 统一Ｌ…     

软件拾零

Ｃａｃｈｅ离线浏览器这是一套整理Ｃａｃｈｅ的软件。当您浏览某个站点后，不论图像还是Ｊａｖａ等资料均会暂时存在您的Ｃａｃｈｅ目录里，不过这些资料都很难从名称上判断其内容。ＮｅｔｓｃａｐｅＣａｃｈｅＥｘｐｌｏｒｅｒ的目的就是帮助用户分门别类地整理这些保存...     

An Effective Cache Replacement Algorithm in Transcoding-Enabled Proxies

In this paper, we address the problem of cache replacement for transcoding proxy caching. Transcoding proxy is a proxy that has the functionality of transcoding a multimedia object into an appropriate format or resolution for each client. We first propose an effective cache replacement algorithm for transcoding proxy. In general, when a new object is to be cached, cache replacement algorithms evict some of the cached objects with the least profit to accommodate the new object. Our algorithm takes into account of the inter-relationships among different versions of the same multimedia object, and selects the versions to replace according to their aggregate profit which usually differs from simple summation of their individual profits as assumed in the existing algorithms. It also considers cache consistency, which is not considered in the existing algorithms. We then present a complexity analysis to show the efficiency of our algorithm. Finally, we give extensive simulation results to compare the performance of our algorithm with some existing algorithms. The results show that our algorithm outperforms others in terms of various performance metrics.     

针对固定码率(CBR)流媒体的动态替换算法(DRA)

流媒体代理服务器缓存是针对流媒体访问的一项技术,能有效的提高流媒体访问质量。缓存算法是缓存代理服务器的重要技术组成部分,包括缓存保存方式、替换算法及进入策略三个方面。文中将介绍一套针对固定码率(CBR)流媒体的缓存算法,在包含码率分级保存方法的同时,使用了包含流媒体缓存基本特性的动态替换算法(DRA,Dynamic Replication Algorithm)。     

Proxy-based hybrid cache management in Mobile IP systems

In this paper, we propose and analyze a proxy-based hybrid cache management scheme for client-server applications in Mobile IP (MIP) networks. We leverage a per-user proxy as a gateway between the server and the mobile host (MH) such that any communication between the MH and server must pass through the proxy. The proxy has dual responsibilities in our design. It keeps track of the current location of the MH by acting as a regional Gateway Foreign Agent (GFA) as in the MIP Regional Registration protocol for mobility management. The proxy is also responsible for cache consistency management and query processing on behalf of the MH. To reduce the network traffic, a threshold-based hybrid cache consistency management policy is applied. That is, when a data object is updated at the server, the server sends an invalidation report to the MH through the proxy to invalidate the cached data object, provided that the size of the data object exceeds the given threshold. Otherwise, the server sends a fresh copy of the data object through the proxy to the MH. We identify the best “threshold” value that would minimize the overall network traffic incurred due to mobility management, cache consistency management, and query processing, when given a set of parameter values characterizing the operational and workload conditions of the MIP network.     

Performance evaluation of Web proxy cache replacement policies

The continued growth of the World-Wide Web and the emergence of new end-user technologies such as cable modems necessitate the use of proxy caches to reduce latency, network traffic and Web server loads. In this paper we analyze the importance of different Web proxy workload characteristics in making good cache replacement decisions. We evaluate workload characteristics such as object size, recency of reference, frequency of reference, and turnover in the active set of objects. Trace-driven simulation is used to evaluate the effectiveness of various replacement policies for Web proxy caches. The extended duration of the trace (117 million requests collected over 5 months) allows long term side effects of replacement policies to be identified and quantified.

Our results indicate that higher cache hit rates are achieved using size-based replacement policies. These policies store a large number of small objects in the cache, thus increasing the probability of an object being in the cache when requested. To achieve higher byte hit rates a few larger files must be retained in the cache. We found frequency-based policies to work best for this metric, as they keep the most popular files, regardless of size, in the cache. With either approach it is important that inactive objects be removed from the cache to prevent performance degradation due to pollution.     

Linux下基于Squid的多能代理系统与透明网关解决方案

本文给出一个Linux下基于Squid的多能代理系统与透明网关解决方案，允许内部网络通过NAT透明网关访问外部网络的同日寸，并给出外部网络分享Squid缓存的方法，同日寸给出一套端口密码动态切换和自动封禁的机制。通过在网关开设硬盘空间存放缓存，可以提高40％网络请求的访问速度，效果良好。     

部分缓存算法在流媒体内容分发网络中的应用研究

内容分发网络是互联网中解决响应速度、提高服务质量的一种应用技术,而流媒体内容分发网络是将内容分发网络应用于流媒体传输领域。流媒体内容分发网络中的边缘服务器缓存策略是流媒体内容分发网络的核心。本文深入研究了现有各种缓存策略;在流媒体内容分发网络中,提出了一种部分缓存算法。实践证明,这种部分缓存策略能明显提高流媒体内容分发网络的并发性能、命中率和服务质量等性能。     

基于高斯混合模型的Web代理服务器缓存替换策略

Web代理服务器缓存能够在一定程度上解决用户访问延迟和网络拥塞问题,Web代理缓存的缓存替换策略直接影响缓存的命中率,从而影响网络请求响应的效果;为此,使用一种通过固定大小的循环滑动窗口提取Web日志数据的多项特征,并使用高斯混合模型对Web日志数据进行聚类分析,预测在窗口时间内可能再次访问到Web对象,结合最近最少使用(LRU)算法,提出一种新的基于高斯混合模型的Web代理服务器缓存替换策略;实验结果表明,与传统的缓存替换策略LRU、LFU、FIFO、GDSF相比,该策略有效提高了Web代理缓存的请求命中率和字节命中率。     

一种新的基于代理缓存的流媒体分送策略

提出了一种新的带缓存的补丁调度策略,有效地将代理缓存与服务器调度技术结合起来,采用基于缓存窗口自适应伸缩的缓存分配方案,实现了流媒体对象在代理服务器中缓存的数据段数与其流行度成正比的原则。理论分析及实验结果表明,该策略有效地降低了服务器及骨干网络带宽资源的消耗,对于客户请求到达速率的变化具有非常好的适应性。     

Web object-based storage management in proxy caches

Proxy caches are essential to improve the performance of the World Wide Web and to enhance user perceived latency. Appropriate cache management strategies are crucial to achieve these goals. In our previous work, we have introduced Web object-based caching policies. A Web object consists of the main HTML page and all of its constituent embedded files. Our studies have shown that these policies improve proxy cache performance substantially.In this paper, we propose a new Web object-based policy to manage the storage system of a proxy cache. We propose two techniques to improve the storage system performance. The first technique is concerned with prefetching the related files belonging to a Web object, from the disk to main memory. This prefetching improves performance as most of the files can be provided from the main memory rather than from the proxy disk. The second technique stores the Web object members in contiguous disk blocks in order to reduce the disk access time. We used trace-driven simulations to study the performance improvements one can obtain with these two techniques. Our results show that the first technique by itself provides up to 50% reduction in hit latency, which is the delay involved in providing a hit document by the proxy. An additional 5% improvement can be obtained by incorporating the second technique.     

一种新的基于分区的多媒体代理协作管理策略

多媒体代理缓存是提高媒体流化质量和减轻网络负载的重要手段，将基于协作的多媒体代理缓存技术引入无线网络，提出一种新的分区缓存管理模型（Partition-based caching manager,PBCM)，通过对系统中各个代理的部分缓存空间（称为静态分区）采取集中式管理，可以合理配置缓存资源，降低缓存的冗余度，从全局角度优化系统的整体性能，具体地，PBCM中制定了一种全局对象放置策略来管理静态分区缓存的内容，该策略被模型化为一个优化问题，并采用改进遗传算法来求解，仿真实验表明该模型及算法是有效可行的。