Assignment 4

Due Wednesday, March 11, 2015 at 6:00pm via sakai

Introduction

Please answer the questions concisely.

Submission

Please remember to submit your assignment as plain text, in-line HTML on sakai, or pdf (if necessary) only. You will get no credit and no second chance to resubmit any documents in Microsoft Word, Apple Pages, or other formats that will require me to run an application to read your submission.

Pay attention to the deadline and strive to get your submission well before that time to allow for any last-minute glitches. No extensions will be given.

Reading/skimming

  • Weeks 5-6 lecture notes.
  • Chapter 7 (Memory management): p. 325-364
  • Chapter 8 (Virtual memory): 8.0-8.8: p. 371-413;
    8.9.2-8.9.4 (page size, TLB reach, inverted page tables): p. 414-416;

Questions

  1. [7.15] Compare paging with segmentation with respect to the amount of memory required by the address translation structures in order to convert virtual addresses to physical addresses.
  2. Assuming a 4 KB page size (12-bit offsets), what are the page numbers and offsets for the following address references (provided as decimal numbers):
    a. 1
    b. 4097
    c. 8193
    d. 503931
    e. 50568453
  3. [7.20] Consider a paging system with the page table stored in memory.
    a. If a memory reference takes 200 nanoseconds, how long does a paged memory reference take?
    b. If we add TLBs, and 75 percent of all page-table references are found in the TLBs, what is the effective memory reference time? (Assume that finding a page-table entry in the TLBs takes zero time, if the entry is there.)
  4. [8.17] What is the copy-on-write feature, and under what circumstances is it beneficial? What hardware support is required to implement this feature?