Homework 10

1. (15 points)

   Suppose we have a (tiny) demand-paging system with a page size of 256 bytes. Suppose a process has the following page table:

   Frame	Valid
   8	V
   0	I
   6	V
   0	I
   0	I

   Suppose the pager selects frames from the front of the following list of free frames:
   {3, 1, 4, 2, 5, 7, 9, ...}
   If the process generates the following logical addresses, what are the corresponding physical addresses? Note: logical addresses are in hexadecimal, give your answer in hexadecimal also (this makes the math much easier).

   1. 0000
   2. 010F
   3. 023C
   4. 010E
   5. 0333

2. (21 points)

   Consider the following page-reference string:
   1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6.
   Assuming all frames are initially empty, how many page faults would occur for the following page replacement algorithms, assuming one, two, three, four, five, six, or seven frames? (Yes, you have to do this seven times per algorithm...)

   1. LRU replacement
   2. FIFO replacement
   3. Optimal replacement

3. (18 points)

   Consider a demand-paging system with the following time-measured utilizations:

   CPU Utilization:	20%
   Paging disk:	97.7%
   Other I/O devices:	5%

   For the following actions below, state whether it is likely to increase, decrease, or not change the CPU utilization. Explain your answers.

   1. Install a faster CPU.
   2. Install a larger paging disk.
   3. Increase the degree of multiprogramming.
   4. Decrease the degree of multiprogramming.
   5. Install more main memory.
   6. Install a faster paging disk, or multiple controllers with multiple disks.

You are not required to turn in this homework. Use it instead for practice.