os05-2nd - Operating System 2nd Exam. for 2005 Fall...

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Unformatted text preview: Operating System 2nd Exam. for 2005 Fall Semester Date: 11-30-2005, Time: 09:10 a.m.- 10:40 a.m. Name: Student ID: Dept: There are 9 problems in this examination. The weights for each (sub)problem is indicated. Please do all of them. 1. [Basic Concepts] These are 10(a-j) true or false problems. If your answer is false please give the true statement with respect to the original false one. (a) (4%) [Critical Section] A solution to the critical-section problem must satisfy four requirements: mutual exclusion, progress, bounded wait- ing, and race condition. (b) (4%) [Semaphores] The semaphores are executed atomically. OS pro- vides binary and counting semaphores. The value of a binary semaphore can range only between 0 and 1. The value of counting semaphore can range over an unrestricted domain. In fact, a counting semaphore can be implemented using binary semaphores. 2 (c) (4%) [Semaphores] The busy waiting problem for the classical def- inition of semaphore with nonnegative value can not be completely eliminated with the definition of the wait() and signal() operations that have negative semaphore values. Thus we only limit busy wait- ing to the critical sections of the wait() and signal() operations, and these sections are short. (d) (4%) [Monitors] The signal() operations associated with monitors differ from the corresponding operation defined for semaphores because the signal() operations associated with monitors are not persistent. On the other hand, every signals results in a corresponding increment of the semaphore value even if there are no waiting threads....
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This note was uploaded on 12/29/2009 for the course INFO ENGI 9801 taught by Professor Wu during the Spring '09 term at 東京国際大学.

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os05-2nd - Operating System 2nd Exam. for 2005 Fall...

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