SGI助阵八运

10月6日,作为国际互联网服务器的唯一指定厂商,SGI公司向八运会组委会提供价值118万元的SGI WebFORCE Origin 200集成多处理器Web服务器,用于八运会期间的信息网络服务。 WebFORCE Origin200是S2MP系列产品中的新一代网络服务器。它集MIPS RISC多处理器的功能与可伸缩共享储存多处理器(S2MP)结构于一体,是为WWW和Intranet将来的进一步发展而设计的,可以满足网上多媒体内容要求,并为新一代动态交互的Intranet应用提供服务。同时,WebFORCE服务集成了SGI     

VOD系统节目分送子系统中的多线程技术

VOD（VideoOnDemand,即VOD）技术是当前多媒体应用技术中的一项热点技术。节目分送子系统的目标是根据节目排程自动把省中心视频服务器节目及相应的资料下载到地市州视频服务器中。该文在简介VOD节目分送子系统的基础上,主要讨论了在下载过程中使用的多线程技术。     

8处理器正相宜 IT管理人员青睐多CPU服务器

目前,许多希望所管理的信息系统能够容纳更多用户及处理更大应用的IT管理人员纷纷转向新的多处理器服务器系统。这些新的多处理器服务器系统之所以能够吸引如此多的IT管理人员,主要有以下几个方面的因素:与目前流行的4-CPU服务器相比,这些新的系统具有更好的性能,可更大程度地满足人们日益增长的处理需求,可提供对分布式应用的更有力的支持,并可成为众多小型服务器的理想替代系统。例如,DEC公司的Alpha 8200和8400服务器最多可支     

AMD-760~(TM)MP技术白皮书之——领先的双独立总线技术

高性能……可升级性……易管理性,这些重要特性决定了一款关键任务平台的性能,这类任务对服务器和工作站来说至关重要,因为服务器和工作站都需要高性能计算能力、高性能内存以及强大的I/O子系统。AMD-760TMMP平台是专为服务器/工作站级应用程序设计的一款高性能、双通道多处理器(MP)系统解决方案。由AMD Athlon MP处理器和AMD-     

细解多处理器技术

多处理器技术的分类 PC服务器的多处理器技术实际上可视为早期大型计算机的多处理机技术。所谓多处理机技术就是用两个以上的处理机去协同处理同一套任务,其体系结构可分为对称多处理机(SMP--SymmetricMultiProcessor)和大规模并行处理机(MPP-     

科技要闻

AMD推出首款服务器用多处理器平台 AMD近日在台北国际电脑展(Computex)上宣布推出其首款供服务器及工作站用的多处理器平台,预计新平台的推出使AMD可以进一步拓展商用系统市场。这个多处理器平台采用AMD Athlon MP处理器及AMD—760MP芯片组,可支持双倍数据传输率(DDR)存储器,而且更采用AMD最新推出的Smart MP技术。 AMD计算产品部工作站及服务器市场营销副总裁表示“根据业内基准测试显示,全新AMD Athlon MP处     

数据仓库的服务器抉择

与其它的数据应用不一样,数据仓库环境本身具有不同的负载特征。要解决数据仓库环境下的服务器选择问题,就必须分析现有的服务器技术,对其特征加以比较,从而针对数据仓库环境的负载特征进行取舍。服务器技术种类从体系结构来看,目前的商用服务器大体可以分为三类,即对称多处理器结构(SMP:SymmetricMulti-Processor),非一致存储访问结构(NUMA:Non-Uni-formMemoryAccess),以及海量并行处理结构(MPP:MassiveParallelProcessing)。每种服务器都有着自己独特的体系结构和特征。SMP(SymmetricMulti-Processor)所谓对称多处理器结构,是…     

基于Telnet的节目分送系统的设计原理与实现

ＶＯＤ技术是当前多媒体应用技术中的一项热点技术,节目分送子系统的目标是根据节目排程自动把省中心视频服务器节目及相应的资料下载到地市州视频服务器中,在简介ＶＯＤ系统的基础上,主要讨论了节目分送系统的原理与实现。     

产品剧场

Acer Altos 22000 Acer向企业用户推出具有业内公认的高品质、高可靠性的服务器系统—新一代Altos 22000多处理器企业级服务器,为企业级用户提供更胜一筹的计算处理能力,是企业级用户的     

ATCA媒体资源服务器中存储刀片的实现

媒体资源服务器是IP多媒体子系统中的一个重要实体,而文件存储又是媒体资源服务器的一个关键功能．本文介绍了ATCA存储刀片作为媒体资源服务器中存储资源的技术实现．该方案还可以作为一种通用的设计,在ATcA架构的产品中用来代替中小规模的磁盘阵列柜,提高产品的集成度．     

Multiprocessors should support simple memory consistency models

In the future, many computers will contain multiple processors, in part because the marginal cost of adding a few additional processors is so low that only minimal performance gain is needed to make the additional processors cost effective. Intel, for example, now makes cards containing four Pentium Pro processors that can easily be incorporated into a system. Multiple processor cards like Intel's will help multiprocessing spread from servers to the desktop. But how will these multiprocessors be programmed? The evolution of the programming model is already under way. One important function of the programming model is to describe how memory operates. For a multiprocessor, a reasonable model is sequential consistency (SC), which makes a multiprocessor behave like a multitasking uniprocessor. Nevertheless, many commercial multiprocessors support more relaxed memory models. The author argues that multiprocessors should support SC because-with speculative execution, relaxed models do not provide sufficient additional performance to justify exposing their complexity to the authors of low level software     

Distributed two-level cloud-based multimedia task scheduling

Recently, Multimedia cloud is emerging as a promising technology to effectively process multimedia services. A key problem in multimedia cloud is how to deal with task scheduling and load balancing to satisfy the quality of service demands of users. In this paper, we propose a two levels task scheduling mechanism for multimedia cloud to addresses the problem. The first level scheduling is from the users’ multimedia application to the data centers, and the second is from the data centers to servers. The data centers and virtual machines both are modeled as M/M/1 queuing systems. The algorithm proposed formulates the task-scheduling problem as cooperative game among data centers. Then we allocate the tasks received by a data center to servers using cooperative game again among servers. Various simulations are conducted to validate the efficiency of the proposed task scheduling approaches. The results showed that the proposed solutions provided better performance as compared to the existing approaches.     

Multimedia Caching Strategies for Heterogeneous Application and Server Environments

In a multimedia system, storage and bandwidth are critical resources since any presentation requires a large volume of data to be delivered in real-time. Caching of multimedia documents in local storage can alleviate large retrieval bandwidth requirements. An important requirement for a multimedia caching policy is to guarantee continuous delivery even when a stream is served from cache. It should also cope with dynamic changes in workload and heterogeneity arising from large and small multimedia files. The proposed Generalized Interval Caching (GIC) policy, that caches intervals between successive streams of a large file as well as entire small files, satisfies all the above criteria. A caching policy needs to cope with additional challenges in a large scale distributed multimedia environment consisting of many heterogeneous servers. The issues include a) routing of requests to ensure good cache hits in each server, and b) balancing of loads across servers. For routing of requests, we introduce the notion of an asset group and propose an affinity routing policy based on this concept. Finally, we adapt the GIC policy for load balancing across servers.     

基于托管完成端口的流媒体交换矩阵模型

在设计服务器数目较多的流媒体业务时,如果客户端在多个服务器之间频繁切换,不仅会加重服务器的负担,还会增大对动态变化的客户组的管理难度.流媒体交换矩阵通过转发流媒体数据包,在两者之间建立映射关系,较好地解决了这一问题.为提高流媒体交换矩阵对数据包的转发速率,在对两种典型的网络模型进行比较之后,提出结合.NET平台,以托管完成端口机制作为流媒体交换矩阵的底层网络I/O模型.经测试,不仅可有效提高对数据包的转发速率,而且做到了跨平台实现,扩大了流媒体交换矩阵产品的应用范围.     

Application-Layer Protocol for Collaborative Multimedia Presentations

Many multimedia presentation applications involve retrieval of objects from more than one collaborating server. Presentations of objects from different collaborating servers might be interdependent. For instance, we can consider distributed video servers where blocks of movies are distributed over a set of servers. Here, blocks of a movie from different video servers have to be retrieved and presented continuously without any gaps in the presentation. Such applications first need an estimate of the available network resources to each of the collaborating server in order to identify a schedule for retrieving the objects composing the presentation. A collaborating server can suggest modifications of the retrieval schedule depending on its load. These modifications can potentially affect the retrieval schedule for other collaborating applications. Hence, a sequence of negotiations have to be carried out with the collaborating servers in order to commit for a retrieval schedule of the objects composing the multimedia presentation. In this paper, we propose an application sub-layer protocol, Resource Lock Commit Protocol (RLCP), for handling the negotiation and commitment of the resources required for a collaborative multimedia presentation application.     

Load sharing in distributed multimedia-on-demand systems

Service providers have begun to offer multimedia-on-demand services to residential estates by installing isolated, small-scale multimedia servers at individual estates. Such an arrangement allows the service providers to operate without relying on a highspeed, large-capacity metropolitan area network, which is still not available in many countries. Unfortunately, installing isolated servers can incur very high server costs, as each server requires spare bandwidth to cope with fluctuations in user demand. The authors explore the feasibility of linking up several small multimedia servers to a (limited-capacity) network, and allowing servers with idle retrieval bandwidth to help out servers that are temporarily overloaded; the goal is to minimize the waiting time for service to begin. We identify four characteristics of load sharing in a distributed multimedia system that differentiate it from load balancing in a conventional distributed system. We then introduce a GWQ load sharing algorithm that fits and exploits these characteristics; it puts all servers' pending requests in a global queue, from which a server with idle capacity obtains additional jobs. The performance of the algorithm is captured by an analytical model, which we validate through simulations. Both the analytical and simulation models show that the algorithm vastly reduces wait times at the servers. The analytical model also provides guidelines for capacity planning. Finally, we propose an enhanced GWQ+L algorithm that allows a server to reclaim active local requests that are being serviced remotely. Simulation experiments indicate that the scheduling decisions of GWQ+L are optimal, i.e., it enables the distributed servers to approximate the performance of a large centralized server     

IMS Application Servers: Roles, Requirements, and Implementation Technologies

The IP multimedia subsystem (IMS) defines a generic architecture to support communication services over a Session Initiation Protocol (SIP) infrastructure. In the IMS architecture, application servers host and execute the IMS service logic. These servers can be SIP application servers, open services architecture (OSA) application servers, or a customized applications for mobile networks using enhanced logic (Camel) service environment. Some technologies used in telephony and voice-over-IP (VoIP) application servers are also applicable to IMS application servers, but such servers have some unique requirements that could limit the extent to which these technologies can meet them.     

Wireless resource management mechanism with green communication for multimedia streaming

In the face of massive parallel multimedia streaming and user access, multimedia servers are often in an overload state, resulting in the delay of service response and the low utilization of wireless resources, which makes it is difficult to satisfy the user experience quality. Aiming at the problems of low utilization rate of multimedia communication resources and large computing load of servers, this paper proposes a self management mechanism and architecture of wireless resources based on multimedia flow green communication. First, based on the combination of multimedia server, relay base station and user cluster, a multimedia green communication system architecture is built based on the comprehensive utilization rate of multimedia communication, and a cluster green communication control algorithm is proposed. Secondly, aiming at the dynamic service demand and asynchronous multimedia communication environment, aiming at ensuring the balance of resource allocation and accelerating the speed of resource allocation, we build a dynamic multimedia wireless resource architecture. Finally, the experimental results of statistics and analysis, from the server in different scale parallel multimedia streams under different scale delay, number of users relay network free resources proportion, user satisfaction, packet loss rate and other performance show that the proposed algorithm is effective and feasible.

     

分布式多媒体系统的设计要点

分布式多媒体系统由于其管理的信息的特点,其设计和实现在许多方面不同于一般的分布式系统。本文根据国内外研究的情况,从系统结构、服务器、客户机、网络等方面讨论分布式多媒体系统的设计要点,重点讨论服务策略和服务质量控制问题。     

Collaborative Multimedia Presentations in Mobile Environments

Distributed multimedia documents systems, distributed video servers are examples of multimedia presentations involving collaboration among multiple information sources. In such applications, objects have to be retrieved from their sources and presented to users according to specified temporal relationships. Objects retrieval in these collaborative applications is influenced by their presentation times, durations, and network throughput available to their sources. Replication of objects amongst the set of collaborating systems gives a choice for object retrieval. Client going through a multimedia presentation can be in a mobile environment. Here, object retrievals from collaborating servers are carried out by base stations to which the client is attached. Mobile client then downloads objects from the base station.In this paper, we present a graph-search based algorithm for computing and negotiating throughput requirements of collaborating multimedia presentations with replicated objects in a mobile environment. This algorithm maximizes the number of cached objects (that have already been played) for handling operations such as reverse presentation.