CS439: Principles of Computer Systems
Homework 8, Part 1
Due in Section on Friday, April 1, 2016 Part 1 of the
homeworks must be completed before section and brought to section. Please refer to the
homework turnin instructions.
Consider a multi-level paging system with 128 pages and a page size
of 256 bytes. The system has 1024 bytes of physical memory and is
byte addressable. Assume the first-level page table holds 8
- How many bits are in a physical address?
- How many bits of the virtual address represent the
first-level page table?
- How many bits of the virtual address represent the page number?
- How many bits are in the complete virtual address?
- What size are the page frames?
Disk requests come into the disk driver for tracks 10, 22, 20, 2, 40,
6, and 38, in that order. A seek takes 6 msec per track moved. How
much seek time is needed for the following scheduling algorithms?
c) LOOK (SCAN, but doesn't move to the end)
In all cases, the arm is initially at track 20, and you may assume
that the head is traveling towards higher numbers.
from Tannenbaum Chapter 5 Number 24.
The MegaGiga hard disk rotates at 5400 rpm with an arm seek time given
by = 4 + 0.05t msec, where t is the number of tracks the
arm seeks. Assume a block size of 512 bytes, and 1024 tracks with 512
blocks/track, and 2 platters with 4 usable surfaces.
The disk controller and DMA read or write data from/to disk at a rate of
What is the storage capacity of the disk?
Pooh Software Ltd. is selling a file system that
uses a UNIX-like file system with multi-level indexing. For more reliability,
the inode array is actually replicated on the disk in two different places.
The intent is that if one or a group of sectors that are storing either
replica of the array become bad, the system can always recover from the
replica. Discuss the effect of having this replicated data structure on
Jane would like to append data to the file
/usr/jane/classes/cs439/exam_study_notes.txt. Assuming she has
the correct permissions, describe the steps the operating system
would need to take to append the data.