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重大操作系统复习提纲

发布时间:2014-06-17 11:54:31  

习题
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12.3 What is a file management system?
12.6 Why is the average search time to find a record in a file less for an indexed sequential file than for a sequential file?

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12.3 A file management system is that set of system software that provides services to users and applications in the use of files. 12.6 In a sequential file, a search may involve sequentially testing every record until the one with the matching key is found. The indexed sequential file provides a structure that allows a less exhaustive search to be performed.

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Fixed blocking: F =B div R Variable-length spanned blocking: F =(B- P)/(R+ P) Variable-length unspanned blocking: F =(B-R/2)/R

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12.3 What file organization would you choose to maximize efficiency in terms of speed of access, use of storage space, and ease of updating (adding/deleting/modifying) when the data are
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a. updated infrequently and accessed frequently in random order? b. updated frequently and accessed in its entirety relatively frequently? c. updated frequently and accessed frequently in random order?

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a. Indexed b. Indexed sequential c. Hashed or indexed

复习提纲

考试说明
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试卷为英文卷,可以中文回答,也可以 英文回答。 考试内容为教材第1—12章教学内容。 最后成绩组成:理论考试(50%)+实验 (20%)+课后作业(20%)+测验 (10%) 试卷内容包含:教学内容、每章节后的 习题、测验题、实验题等

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Processor management Memory management I/O and File system

Processor management
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Program execution Modal
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Serial execution Concurrent execution
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Process Thread

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Parallel execution

Processor management
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Process
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What is Process? Process Control Block Process States ? New: A process that has just been created but has not yet
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been admitted to the pool of executable processes by the OS. Ready: A process that is prepared to execute when given the opportunity. Running: The process that is currently being executed. Blocked: A process that cannot execute until some event occurs. Exit: A process that has been released from the pool of executable processes by the OS.

Processor management
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Modes of Process Execution
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User mode System mode process switching——When to Switch Process

Processor management
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Processor Scheduling
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Aim of Scheduling
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Response time Throughput Processor efficiency

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First-Come-First-Served Round Robin Shortest Process Next Shortest Remaining Time Highest Response Ratio Next Feedback

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Real-Time Scheduling

Processor management
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Mutual Exclusion and Synchronization
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critical resource(临界资源): nonsharable resource. Critical section(临界区): program to access critical resource Semaphores
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semWait semSignal

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Monitors Message Passing

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