Memory Reference - Operating Systems and System Programming - Exams, Exams of Operating Systems

Main points of this exam paper are: Memory Reference, Main Memory, Regular Page, Page Table, Table Indicated, Main Memory, Regular Page, Tradeoffs, One Process, Scheduler

Typology: Exams

2012/2013

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UNIVERSITY OF CALIFORNIA
College of Engineering
Department of Electrical Engineering
and Computer Sciences
Computer Science Division
CS 162, Fall, 2001 Prof. Alan Jay Smith
Midterm 1, October 8, 2001
Part I
You have until the time announced for this exam. The exam is closed book and closed notes. All answers should be
written on the exam paper. Anything that we can’t read or understand won’t get credit. Any question for which you give
no answer at all will receive 25% partial credit. Please answer in standard English; illiterate or illegible answers to
essay questions will lose credit. If we can’t understand your answer, it is wrong. Partial credit will be given for “compu-
tation-type” problems only if your errors are obvious to the grader; we are not going to spend significant time debugging
your solution. If necessary, you may continue on the back of a page. Please watch the front board for corrections and
other information. This exam has 7 questions on 7 pages and is in two parts. Answers may be continued on the back of
a page.
Name (last, first, middle):______________________________________
Student ID #_________________________ Code #_____________________
Class Account:____________________________________
1. The discussion of a hashed (inverted) page table indicated that the size of the table was propor-
tional to the size of main memory. Why? Do you also need a regular page table? Why? How large
is the regular page table? (12)
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UNIVERSITY OF CALIFORNIA

College of Engineering Department of Electrical Engineering and Computer Sciences Computer Science Division

CS 162, Fall, 2001 Prof. Alan Jay Smith Midterm 1, October 8, 2001 Part I

You have until the time announced for this exam. The exam is closed book and closed notes. All answers should be written on the exam paper. Anything that we can’t read or understand won’t get credit. Any question for which you give no answer at all will receive 25% partial credit. Please answer in standard English; illiterate or illegible answers to essay questions will lose credit. If we can’t understand your answer, it is wrong. Partial credit will be given for “compu- tation-type” problems only if your errors are obvious to the grader; we are not going to spend significant time debugging your solution. If necessary, you may continue on the back of a page. Please watch the front board for corrections and other information. This exam has 7 questions on 7 pages and is in two parts. Answers may be continued on the back of a page.

Name ( last , first, middle):______________________________________

Student ID #_________________________ Code #_____________________

Class Account:____________________________________

  1. The discussion of a hashed (inverted) page table indicated that the size of the table was propor- tional to the size of main memory. Why? Do you also need a regular page table? Why? How large is the regular page table? (12)

Name (last, first, middle):______________________________________

  1. List and explain as many tradeoffs as you can between writing a program using: (a) one process, (b) multiple processes, and (c) one process with threads, to solve a problem. (12)

Name (last, first, middle):______________________________________

  1. You have processes 1...4 with arrival times and CPU processing requirements as shown. For each of the following scheduling algorithms, show (in a table or diagram) at each time which process is running on the CPU. Compute the average flow time over this set of jobs. You may assume that there are no overhead costs. (16)

Process Arrives CPU time 1 0 3 2 2.1 1 3 3.2 5 4 4.3 2

a) RR (quantum = 0.5) b) SRPT c) SJF d) SET (quantum = 0.5)

Name (last, first, middle):______________________________________

  1. For the following two cases, please either show a complete safe sequence or prove that there isn’t one (12):

Process has-X has-Y max-needs-X max-needs-Y A 10 20 75 50 B 0 70 50 90 C 30 10 60 40 D 50 80 100 220

(a) available: X: 40 Y: 40 (b) available: X: 40 Y: 35

Name (last, first, middle):______________________________________

  1. Explain what an open (queuing) system is and what a closed system is. Does the scheduling algorithm affect the throughput in a closed system? In an open system? Does it affect the flow time in a closed system? In an open system? Please explain your answers. (16)