perating System

Q 1.Do Problem 15.4(a,b,c) from the text:

For the DAC model discussed in Section 15.3, an alternative representation of the protection state is a directed graph. Each subject and each object in the protection state is represented by a node (a single node is used for an entity that is both subject and object). A directed line from a subject to an object indicates an access right, and the label on the link defines the access right.

a. Draw a directed graph that corresponds to the access matrix of Figure 15.3a. b. Draw a directed graph that corresponds to the access matrix of Figure 15.5. c. Is there a one-to-one correspondence between the directed graph representation

and the access matrix representation? Explain. 15.4 diagrams

15.4 a b c diagram

15.3

2. Ignoring overhead for directories and file descriptors, consider a file system in which files are stored in blocks of 16K bytes. For each of the following file sizes, calculate the percentage of wasted file space due to incomplete filling of the last block: 41,600 bytes; 640,000 bytes; 4.064,000 bytes. Fill out the table below for your answer:

File size 41,600 bytes 640,000 bytes 4,064,000 bytes NR. of blocks Total capacity

Wasted space % of wasted space