Lecture14nFull - COT 4600 Operating Systems Spring 2011...

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Click to edit Master subtitle style 8/1/11 Lecture 14 COT 4600 Operating Systems Spring 2011 Dan C. Marinescu Office: HEC 304 Office hours: Tu-Th 5:00 – 6:00 PM
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Lecture 14 8/1/11 n Last time: n Midterm ¨ Today n Solution of the midterm problems and midterm discussion ¨ Next time n Virtualization n Locks Lecture 14 – Tuesday, March 15, 2011 22
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Lecture 14 8/1/11 Naming n Conceptual/abstract model: a description which retains the most important characteristics of the process/object in a given context. ¨ The model of an airplane wing ¨ The abstraction of an interpreter 33
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Lecture 14 8/1/11 Example 1- abstract model of an interpreter – Figure 2.5 44
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Lecture 14 8/1/11 Naming MODEL – (see Lecture 8) n Naming allows objects ¨ to refer to each other ¨ to locate another objects ¨ to determine the properties of other objects n for a spectrum of objects and implementations; examples ¨ Searching for an address in phone book ¨ Compiling a program which uses a library ¨ Identifying the registers used during execution of a compiled program n Four components: n Name space (the universe of names) n Mapping function n The universe of values n Context ¨ A function which has as input: a name and a context and produces a value 55
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Lecture 14 8/1/11 Example 2: Abstract model of naming: Figure 2.10 66
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Lecture 14 8/1/11 The role of the context for modular sharing n Modular sharing: allows one module to use another module developed independently, without the danger of name collision (page 117 of the text book) n All names encountered during the name resolution for module A are resolved using the context of A; in other words trhe context of module A points to all modules used by A (including A); n The context allows modular sharing; if both modules A and B use a function called W, but the two functions are different (call them WA and WB for convenience) then the context of A will point to the function WA and the context of B will point to WB 77
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Lecture 14 8/1/11 Example: context used for modular sharing, Figure 3.5 88
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Lecture 14 8/1/11 99
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Lecture 14 8/1/11 Problem 2 – UNIX file system n Lecture 8 ¨ Basic concepts related to file handling ¨ How UNIX users access a file – API ¨ Internal implementation of file operations for a generic system n How to map logical to physical organization ¨ UNIX 1010
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Lecture 14 8/1/11 B. The software layer: the file abstraction n File: memory abstraction used by the application and OS layers ¨ linear array of bits/bytes ¨ properties: n durable X information will not be changed in time n has a name „ n which defines the current position in the file. n
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Lecture14nFull - COT 4600 Operating Systems Spring 2011...

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