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5 USING PATHS FOR RESOURCE MANAGEMENT

USING PATHS FOR RESOURCE MANAGEMENT

The greatest of all gifts is the power to
estimate things at their true worth.

-- La Rochefoucauld


This chapter serves two purposes. First, it provides a concrete example for building a simple, yet fully functional Scout appliance. The appliance presented is a network-attached TV that can display MPEG encoded video [54, 67].

Second, this chapter demonstrates path-derived resource management benefits. To emphasize resource management---as opposed to the path-code related benefits described in the previous chapter---it is best to choose an appliance that spends most of its CPU time in just one or a few modules. To this end, MPEG decoding is ideal. This compression algorithm is capable of reducing the size of a video by a factor of 10 to 100 and with this high compression ratio comes a relatively expensive decompression algorithm. Workstations have only recently become fast enough to perform MPEG decoding in realtime. For example, on a first generation Alpha, it is not atypical that displaying a single video uses up all available CPU time---ninety percent or more of which is spent in the MPEG decoder. This means that code-path overhead such as cross-module call overhead or extraneous operations due to abstraction boundaries are irrelevant for all practical purposes. On the other hand, proper resource management, such as CPU scheduling or buffer management, is crucial when multiple loads are put on the system simultaneously.

5.1 Building NetTV

5.2 Resource Management


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