Next-generation distributed systems will support corLtLzLzLous medLa (digztal audio and video) in the same framework as other data. Many applications that use continuous media need guaran-teed end-to-end performance (bounds on throughput and delay). To reliably support these requirements, system components such as CPU schedulers, networks, and file systems must offer performance guarantees. A rnetasclzedtder coordinates these components, negotiating end-to-end guarantees on behalf of clients. The CM-resource model, described in this paper, provides a basis for such a metascheduler. It defines a workload parameterizatlon, an abstract interface to resources, and an algorithm for reserving multiple resources. The model uses an economic approach to dividing end-to-end delay, and it allows system components to “work ahead,” improving the performance of nonreal-time workload.

Fiber-Distributed Data Interface (FDDI) is a lOO-Mbps Local Area Network (LAN) standard being developed by the American National Standards Institute (ANSI). It uses a timed-token access method and allows up to!jOO stations to be connected with a total fiber length of 200 km. We analyze the performance of FDDI using a simple analytical model and a simulation model. The performance metrics of response time, efficiency, and maximum access delay are considered. The efficiency is defined as the ratio of maximum obtainable throughput to the nominal bandwidth of the network. The access delay is detined as the time it takes to receive a usable token. The performance of FDDI depends upon several workload parameters; for example; the arrival pattern, frame size, and configuration parameters, such as the number of stations on the ring, extent of the ring, and number of stations that are waiting to transmit. In addition, the performance is affected by a parameter called the Target Token Rotation Time (TTRT), which can be controlled by the network manager. We considered the effect of TTRT on various performance metrics for different ring configurations, and concluded that a TTRT value of 8 m.3 provides a good performance over a wide range of configurations and workloads. 1

In computer graphics, rendering is the process by which an abstract description of a scene is converted to an image. When the scene is complex, or when high-quality images or high frame rates are required, the rendering process becomes computationally demanding. To provide the necessary levels of performance, parallel computing techniques must be brought to bear. Although parallelism has been exploited in computer graphics since the early days of the field, its initial use was primarily in specialized applications. The VLSI revolution of the late 1970Õs and the advent of scalable parallel computers during the late 1980Õs changed this situation. Today, parallel hardware is routinely used in graphics workstations, and numerous software-based rendering systems have been developed for general-purpose parallel architectures. This article provides a broad introduction to the subject of parallel rendering, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of parallel rendering algorithms and systems. We examine the different types of parallelism and how they can be applied in rendering applications. Concepts from parallel computing, such as data decomposition, task granularity, scalability, and load balancing, are considered in relation to the rendering

In the past couple of years, significant progress has been made in the development of message-passing libraries for parallel and distributed computing, and in the area of high-speed networking. These advances in computing technology have also led to a tremendous increase in the amount of data being manipulated and produced by scientific and commercial application programs. Despite their popularity, message-passing libraries only provide part of the support necessary for most high performance distributed computing applications -- support for high speed parallel I/O is still lacking. In this paper, we provide an overview of the conceptual design of a parallel and distributed I/O file system, the Virtual Parallel File System (VIP-FS), and describe its implementation. VIP-FS makes use of message-passing libraries to provide a parallel and distributed file system which can execute over multiprocessor machines or heterogeneous network environments.

This letter examines the optimality of three published `optimal' synchronous bandwidth allocation (SBA) schemes for guaranteeing synchronous message deadlines with the timed token medium access control protocol. It is found that none of these three schemes is optimal. The non-optimality has been demonstrated by a numerical example and the root cause behind has been indicated. The development of an optimal SBA scheme remains a challenge.

this report we will derive some properties of token rotation time and then use these properties to yield a close formula for the minimum total synchronous message transmission time a node can have during any message period. 2 Background and Definitions

The IEEE Working group 802.17 is standardizing a new ring topology network architecture, called the Resilient Packet Ring (RPR), to be used mainly in metropolitan and wide area networks. This paper presents a technology background, gives an overview, and explains some of the design choices behind RPR. Some major architectural features are illustrated and compared by showing performance evaluation results using the RPR simulator developed at Simula Research Laboratory using the OPNET Modeler simulation environment.

Networks that use the timed token protocol (such as the 100 Mbit/s FDDI network) are well suited for real-time applications because they guarantee, to each node, an average bandwidth and a bounded access time to the communication network. This guarantee is necessary but not sufficient for the timely delivery of deadline-constrained messages; protocol parameters must be carefully selected to ensure that these messages meet their deadlines. This paper addresses the issue of selecting the protocol parameters TTRT (Target Token Rotation Time) and the synchronous capacities assigned to each node. The objective is to guarantee that each synchronous message is transmitted before its deadline. An upper bound is derived on the Worst Case Achievable Utilization (WCAU) of any parameter selection scheme. The WCAU of a scheme is defined as the maximum utilization U such that the scheme guarantees all synchronous messages as long as their utilization is less than U. An algorithm for selecting the ...

With the current advances in computer and networking technology coupled with the availability of software tools for parallel and distributed computing, there has been increased interests in high-performance distributed computing (HPDC). We envision that HPDC environments with supercomputing capabilities will be available in the near future. However, a number of issues have to be resolved before future network-based applications can exploit fully the potential of HPDC environment. In this paper, we present an architecture of a high-speed local area network and a communication system that provides HPDC applications with high bandwidth and low latency. We also characterize the message-passing primitives required in HPDC applications and develop a communication protocol that implementes these primitives efficiently. 1 Introduction Decades of "experimentation" with parallel and distributed computing has established the importance of handling real-world applications. Enormous amount of rese...

Real-time communication with performance guarantees is expected to become an important and necessary feature of future computer networks. In this paper, we present a scheme which can provide real-time communication services with both absolute and statistical performance guarantees on multiaccess bus networks for given input traffic characteristics and performance requirements. The proposed scheme reserves network bandwidth for real-time connections according to their needs. It also allows for independent addition and deletion of real-time connections while preserving existing guarantees. Our extensive simulation results for motion video communication have shown the proposed scheme to outperform the other well-known schemes.