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OSY216D 2021 S1 A2 - ccc

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OPERATING SYSTEMS III (OSY301T)

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Tshwane University of Technology

Academic year: 2021/2022

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OSY216D S1, 2021 Assignment 2

Page 1 of 3

Faculty of Information and Communication

Technology

Department of Information Technology

Operating Systems 226R Assignment 2

OSY216D

Due Date: 30 July 2021 at 18:

SPECIAL REQUIREMENTS : Submit a typped neat report INSTRUCTIONS TO CANDIDATES: Answer all the questions

NUMBER OF PAGES: 3 APPENDIX: 0

COURSE/S: DIPLOMA IN INFORMATION TECHNOLOGY

EXAMINER Dr. M. MIGABO

MODERATOR Mr. N. MATANGA

TOTAL MARKS: 40 FULL MARKS: 40

OSY216D S1, 2021 Assignment 2

Page 2 of 3

Question 1 – Memory Management: Theory-based questions [22]

Consider a swapping system in which memory consists of the following hole sizes in memory order: 10 MB, 4 MB, 20 MB, 18 MB, 7 MB, 9 MB, 12 MB, and 15 MB. Which hole is taken for successive segment requests of (a) 12 MB (b) 10 MB (c) 9 MB for first fit? Now repeat the question for best fit, worst fit, and next fit. (4)
For each of the following decimal virtual addresses, compute the virtual page number and offset for a 4-KB page and for an 8 KB page: 40000, 16384,
1. (4)
Suppose that a machine has 48-bit virtual addresses and 32-bit physical addresses. (a) If pages are 4 KB, how many entries are in the page table if it has only a single level? Explain. (2) (b) Suppose this same system has a TLB (Translation Lookaside Buffer) with 32 entries. Furthermore, suppose that a program contains instructions that fit into one page, and it sequentially reads long integer elements from an array that spans thousands of pages. How effective will the TLB be for this case? (4)
You are given the following data about a virtual memory system: (a)The TLB can hold 1024 entries and can be accessed in 1 clock cycle (1nsec). (b) A page table entry can be found in 100 clock cycles or 100 nsec. (c) The average page replacement time is 6 msec.

If page references are handled by the TLB 99% of the time, and only 0% lead to a page fault, what is the effective address-translation time? (4)

A student in a compiler design course proposes to the professor a project of writing a compiler that will produce a list of page references that can be used to implement the optimal page replacement algorithm. Is this possible? Why or why not? Is there anything that could be done to improve paging efficiency at run time? (4)

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