Sp06 midterm 2-solutions - University of California,...

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Page 1/12 University of California, Berkeley College of Engineering Computer Science Division – EECS Spring 2006 Anthony D. Joseph Midterm #2 Exam Solutions April 26, 2006 CS162 Operating Systems Your Name: SID AND 162 Login: TA Name: Discussion Section Time: General Information: This is a closed book and notes examination. You have 90 minutes to answer as many questions as possible. The number in parentheses at the beginning of each question indicates the number of points given to the question; there are 100 points in all. You should read all of the questions before starting the exam, as some of the questions are substantially more time consuming. Write all of your answers directly on this paper. Make your answers as concise as possible. If there is something in a question that you believe is open to interpretation, then please ask us about it! Good Luck!! Problem Possible Score 1 19 2 36 3 23 4 22 Total 100
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CS 162 Spring 2006 Midterm #2 Exam April 26, 2006 Solutions Page 2/12 1. (19 points total) Short answer questions: a. (11 points) Translation Look-Aside Buffers: i) (6 points) On a TLB miss in Nachos, what data structures should you check to find a previously referenced page? List the data structures in the order that they should be checked. First, you should check the Inverted Page Table, then the swap file, and finally the application COFF file. Each correct answer was worth two points. We subtracted one point for each incorrect answer or wrong order. ii) (3 points) Give a two to three sentence description of “precise exceptions”. When a precise exception occurs, the Program Counter cleanly divides the fully executed and non-executed instructions – there are no partially executed instructions. iii) (2 points) Briefly (1-2 sentences) say why precise exceptions are nice to have. With precise exceptions, there are no side effects or instructions for the exception handler to undo or rollback, making the OS simpler.
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CS 162 Spring 2006 Midterm #2 Exam April 26, 2006 Solutions Page 3/12 b. (4 points) Networking: i) (2 points) The current version of IP uses 32-bit addresses. List one reason that we cannot use all 2 32 addresses. Two reasons: the hierarchical name allocation yields internal fragmentation of network address space, and some of the address are reserved for private networks or other purposes (e.g., x.y.z.0, 127.0.0.1, or localhost). ii) (2 points) List one reason why it would still be possible to connect more than 2 32 computers to the Internet. Two reasons: Network Address Translation allows multiple computers to be connected using a single IP address, and IP addresses can be time-shared using the Dynamic Host Configuration Protocol. c.
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This homework help was uploaded on 01/30/2008 for the course CS 162 taught by Professor Kubiatowicz during the Spring '02 term at University of California, Berkeley.

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Sp06 midterm 2-solutions - University of California,...

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