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Midterm Review

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Agenda Part 1 quick review of resources, I/O, kernel, interrupts Part 2 processes, threads, synchronization, concurrency Part 3 specific synchronization considerations, concerns and techniques Part 4 classic synchronization problems, examples, and algorithms Part 5 Review of old exams

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Abstract View of System 2004, D. J. Foreman3 User Space O/S Space Application Programming Interface

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Topics Basic functions of an OS Dev mgmt Process & resource mgmt Memory mgmt File mgmt Functional organization General implementation methodologies Performance Trusted software UNIX & WindowsNT organization 2004, D. J. Foreman4

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Design Constraints Performance Security Correctness Maintainability Cost and "sell-ability" Standards Usability 2004, D. J. Foreman5

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Resource Management Resources Memory CPU cycles I/O Includes networks, robot arms, motors That is, any means of getting information (or signals) into or out of the computer 2004, D. J. Foreman6

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Resource Sharing Why do we need to share? Greater throughput Lowers cost of resources Allows more resources to be available 2004, D. J. Foreman7

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Executing User Programs Batch Programming (olden days) Scheduled tasks Maximize throughput Multiprogramming (modern OS) Multiple user programs Timesharing Maximize response time

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I/O Techniques Programmed I/O Processor repeatedly check I/O status register Interrupt-Driven I/O I/O interrupts processor when I/O is ready Processor interrupted and involved in every word of data in the Read/Write DMA Processor delegates the work to the I/O device I/O interrupts processor only upon completion

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Memory Hierarchy registers