M. Hayter. A Workstation Architecture to Support Multimedia. Technical Report 319, University of Cambridge Computer Laboratory, September 1993. Ph.D. Dissertation. (pp 2, 74)  Home/Search   Document Details and Download   Summary   Related Articles   Check

....streams but not their direct manipulation by applications. The observation that bus based workstations (where data traversed the bus many times) were not ideal led to a prototype second generation multimedia workstation replacing the bus with an ATM based interconnect the Desk Area Network [Hayter91, Hayter93, Barham95]. Operating system support for continuous media streams has also been under investigation; the creation of the Pegasus project [Mullender92] was intended to develop such a system. At the time of writing, the Pegasus project has begun an implementation of some of the low levels of such a system. ....

....thread contention or remote invocation need also be considered. A device driver process may have specific scheduling requirements in order to meet its quality of service contracts. In particular it is likely to require a nonblocking access method to I O channels. 73 5.2. 5 Streaming Memory In [Hayter93] the concept of a stream cache was defined. A stream cache is a special area of the cache on a system which is used directly for I O without the data actually being represented in the underlying memory. It is particularly suited to the processing of multimedia streams. The MMU on the system ....

M. Hayter. A Workstation Architecture to Support Multimedia. Technical Report 319, University of Cambridge Computer Laboratory, September 1993. Ph.D. Dissertation. (pp 2, 74)

....: 187 C.4 Mobility Profile Augmentation : 187 Bibliography 189 ix List of Figures 1.1 Structure of the dissertation : 3 2. 1 The CCITT ATM cell format (from [Hayter 93] 7 2.2 Simplified architecture of GSM PLMN system (from [Steele 92] 12 2.3 Architecture of the WINLAB Cellular Packet Switch (from [Goodman 91b] 13 2.4 Wireless addition to the ATM protocol stack (from [Raychaudhuri 94] 18 3.1 Minimum ....

....characteristics and requirements. Each header is also protected by its own Header Checking Code (HEC) UNI NNI GFC VPI VPI VCI 16 PLT 3 C L P t 4 Bits 12 Bits 8 Bits Header (5 Bits) Payload (48 Bytes) HEC 8 Bits i B Bits Bits Figure 2. 1: The CCITT ATM cell format (from [Hayter 93] The channel identifier is partitioned into two parts: the Virtual Path Identifier (VPI) and the Virtual Circuit Identifier. It is possible to multiplex multiple virtual circuits onto a single virtual path between two points of the network. The entities between a virtual path end points need to ....

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M. D. Hayter, "A Workstation Architecture to Support Multimedia," Ph.D. Thesis, Cambridge University Computer Laboratory, November 1993.

....fabric is used as the main bus of the system. Multimedia devices (video and audio, capture and display) and processor 1 Thanks are due to Olivetti Research Ltd. for permission to replicate the design. cache memory systems all using the Fairisle fabric have been built and are described elsewhere [6, 11, 7]. Of more direct relevance to the network research are the Null Port Controller and Multicast fabric. 2.4.1 Null Port Controller The Null Port Controller is a fifo queueing port controller for the Fairisle switch. The device is extremely basic; besides the standard transmission daughter board, ....

M. D. Hayter. A Workstation Architecture to Support Multimedia. Technical Report 319, University of Cambridge Computer Laboratory, 1993. Ph.D. dissertation.

....interconnect has a limited synergy effect when the system is connected to an ATM based LAN or WAN. 1. Introduction The term Desk Area Network (DAN) has been introduced for networks that interconnect devices typically found at a desk top, such as displays, cameras, speakers and microphones [3][6][11] 12] 14] 5] ATM was originally developed to carry integrated communication streams in a Wide Area Network (WAN) It has also shown itself as a viable Local Area technology. The primary advantages of ATM are high bandwidth, ability to carry integrated communication streams, potential for ....

....to carry integrated communication streams, potential for resource reservation, ability to scale, and independence of a given physical layer. ATM is therefore a prime candidate for a DAN. There is an interest in utilizing switching technology, such as ATM, for memory and multiprocessor interconnect [6][5] since the traditional memory buses do not scale [10] For memory interconnect ATM has the following potential advantages: 1) cost effectiveness since ATM chips and modules are proliferating, and 2) ATM used as a memory interconnect could offer synergy between external ATM based communication ....

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M. Hayter, A Workstation Architecture to Support Multimedia, Ph. D Thesis St. John's College, University of Cambridge, September 1993

....approach, the input and output devices are separate components, each independently connected to the network. A similar but slightly less radical approach has been taken by a group which has built clusters of tightly coupled input and output devices around standard workstations [2] Other groups [1,4,5] have been even more radical than us, dividing the workstation itself into separate components, with CPUs, caches and memories all directly connected to the ATM network. We have stopped before this point, preferring instead to concentrate on providing a wide variety of input and output devices and ....

M. Hayter, "A Workstation Architecture to Support Multimedia," PhD Thesis, Cambridge University Computer Laboratory, Technical Report 319, January 1994.

....first to make use of distributed processing methodologies in the ATM control plane, as well as doing extensive traffic analyses on real ATM data. It was also at the Computer Laboratory that the data transfer capabilities of ATM were first used to replace a workstation bus in the Desk Area Network [Hayter93] 2.1.2 Distributed Processing Environments Early Distributed Processing Environments (DPEs) include the Cambridge Distributed Computing System [Needham82] which later matured into the ANSA architecture [Herbert94a] More recently the advent of object oriented technology progressed these ....

M.D. Hayter. A workstation architecture to support multimedia. Technical Report 319, University of Cambridge Computer Laboratory, November 1993. (p 14)

.... Map Cache and Stream Address Error Data in past Trap to kernel Reschedule process Data in future Valid Stream data Valid old data Process sees cache miss User Address Wraps Before Wrap Cache signals kernel Stream data replaces old data in cache User Base Address Frame array [0] 1] 2] 3] 4] [5] [6] 7] 8] 9] A B C D Figure 1: Addressing a Stream Figure 1 illustrates how the address mapping may be done. User addresses will span some space, possibly having to wrap after a large time has passed. As shown, the operating system will set up the memory management unit (or a more specialised ....

....3 The Desk Area Network and the CPU node The Desk Area Network (DAN) is an architecture for a multimedia workstation. Its main feature is the use of an ATM interconnect between the parts of the machine. The architecture was proposed in [6] and has been developed by a series of research projects [2, 5, 8]. The aim is to provide improved system performance by the use of a device and processor interconnect which: ffl permits direct device device as well as CPU device communications, ffl is amenable to implementation as a space division switch fabric, ffl provides frequent preemption points, ffl ....

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MD Hayter. A workstation architecture to support multimedia. Technical Report 319, Cambridge University Computer Laboratory, November 1993. Ph.D. dissertation.

....10 8 shaped video and graphical windows against each other with very little loss of performance, the main bottleneck proving to be the speed at which the processor was capable of draining the receive FIFOs of the ATM interface. 3. 5 The Processor Node The processor node developed for the DAN [Hayter93] allowed investigation of two areas: the use of the interconnect to carry CPU memory traffic and to allow processing to take place on multimedia data types. It is noticeable that in many existing systems multimedia data are second class, the only operations that can usually be performed in ....

.... 44.4 Figure 5: Service Time with High Priority Contention To understand the shape of the graph it is important to note that 74 of accesses are reads with a service time of just under eight cell times and that a single cell time is very large compared 12 These experiments are fully reported in [Hayter93] 10 14 to the CPU speed. Therefore eight cell times after a request there is very likely to be another request. Hence when the gap size is eight and a request succeeds in the first cell time of the gap a subsequent request will collide with the start of the next burst and be delayed. This ....

MD Hayter. A Workstation Architecture to Support Multimedia. Technical Report 319, Cambridge University Computer Laboratory, November 1993. Ph.D. dissertation. (pp 10--9, 10--14)

....and switch fabric of the Fairisle switch to implement a workstation in which the fabric is used as the main bus of the system. Multimedia devices (video and audio, capture and display) and processor cache memory systems all using the Fairisle fabric have been built and are described elsewhere [Hayter91, McAuley93, Hayter93]. Of more direct relevance to the network research are the Null Port Controller and Multicast fabric. 2.4.1 Null Port Controller The Null Port Controller is a fifo queueing port controller for the Fairisle switch. The device is extremely basic; besides the standard transmission daughter board, ....

M. D. Hayter. A Workstation Architecture to Support Multimedia. Technical Report 319, University of Cambridge Computer Laboratory, 1993. Ph.D. dissertation. (p 9--5)

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