CS 377: Homework 4

Due: Friday, April 11, 19:30

OFFICIAL VERSION

Banker's Algorithm:
 1.  Assume we have the following resources: tape drives, graphic displays, printers and  disks. Consider that we have already allocated these resources among four processes as demonstrated by the following Allocation matrixAlso we  have a MAX matrix to describe the maximum resources each process needs. The available resources now are :  Available = (1, 0, 2, 0) for tape drives, graphic displays, printers and  disks, respectively.
Allocation matrix:
    Process Name     Tape Drives     Graphics     Printers     Disk Drives
    Process A                       2                   0                  1                   1
    Process B                       0                   1                   0                   0
    Process C                       1                   0                   1                   1
    Process D                       1                   1                   0                   1
MAX matrix:
    Process Name     Tape Drives     Graphics     Printers     Disk Drives
    Process A                       3                   2                  1                   1
    Process B                        0                  2                   1                  2
    Process C                        4                   1                  1                  1
    Process D                       1                   1                   1                  2
Questions:
   a)  How many total resources are available of the types: tape drives, graphic displays, printers and  disks, respectively?
   b)  What are the contents of the "Need" matrix?
   c)  Is the system in a safe state? Why?
   d)  Suppose Process A were to deallocate its resources and immediately terminate. Is the system in a safe state? Why?
   e)  Suppose further that Process B were to allocate one additional Disk. Is the system in a safe state? Why?

2.  What are the major  disadvantages of the Banker's Algorithm? (list at least three)

Deadlock:
3. Consider a system consisting of four resources of the same type that are shared by three processes, each of which needs at most two resources. Show that the  system is deadlock free (no matter what the current allocation state is).
 

File Systems:

4. What are the advantages and disadvantages of recording the name of the creating program with the file attributes (as is done in the older versions of the Macintosh operating system)?

5. Give an example of an application in which data should be accessed in the following order:
a) Sequentially
b) Randomly

6. How much time did you spend on this assignment?