Operating Systems (CS 377):
Homework 4
Due: November 7, 2002 23:59
Addendum
Please only hand in a raw text file, a postscript file, or a pdf file.
What to Hand In
Everyone must hand in their own work. Place in your Hand-In directory
(~/cs377/hw4/) one of the following: README (raw text file),
README.ps (a postscript file), or README.pdf.
The file must contain your name, user id, and answers to the questions
listed below.
Q1. Discuss the scalability of the following
network topologies: fully connected, partially connected, tree, star,
ring, and multi-access bus network.
Q2. What are the key properties of DNS? List at least 3.
Q3. In terms of reliability, what is the difference between
a transport layer protocol (TCP), and a link layer protocol?
Q4. Consider the following system snapshot using the data
structures in the Banker's algorithm, with resources A,B,C, and D, and
processors P0 to P4. The available resources now are 3,2,1,0 for
A,B,C,D, respectively.
| Processor | Allocation |
Max | Need |
| P | A | B | C | D | A | B | C | D |
A | B | C | D |
| P0 | 3 | 0 | 0 | 2 | 6 | 0 | 1 | 2 | |
| P1 | 1 | 0 | 0 | 0 | 1 | 7 | 5 | 0 | |
| P2 | 1 | 3 | 5 | 4 | 2 | 3 | 5 | 6 | |
| P3 | 0 | 6 | 3 | 2 | 1 | 6 | 5 | 2 | |
| P4 | 0 | 0 | 1 | 4 | 1 | 6 | 5 | 6 | |
- How many resources are there for A, B, C, and D?
- What are the contents of the "need" matrix?
- Is the system in a safe state? Why?
- If a request from process P4 arrives for additional resources
(1,2,0,0), can the Banker's algorithm grant the request immediately?
Why? How about if its additional resource request is (0,1,0,0)?
Q5.
How much time did you spend on this homework assignment?
fagg@cs.umass.edu
Last modified: Mon Oct 22 09:32:53 2002