Chapter 03 – Memory management
I. Problems
3.1. Consider a swapping system in which the memory consists of the following hole sizes: 10 K, 4 K, 20 K, 15 K, 9 K. Assume first fit/ next fit/ best fit algorithm is used.
Which holes are taken for successive segment requests of 8 K, 12 K, 10 K?
3.2. Suppose a virtual address space of 2^28 words and the page size is 2^12 words. If the virtual address is 1234567 in Hexadecimal, what would be the page number in
Hexadecimal?
3.3. A computer has four page frames. The time of loading, time of last access, and the R and M bits for each page are as shown below (the times are in clock ticks):
Page Loaded
Last ref.
R
M
-----------------------------------------------------------------------------------------------------0
226
280
0
0
1
160
265
0
1
2
110
270
1
0
3
120
285
1
1
Which page will LRU replace?
Which page will FIFO replace?
Which page will NRU replace?
Which page will Second chance method replace?
3.4. A machine with 512 MB memory has 64 bit memory word. If the frame size is 16
KB, how many bits are used to indicate the frame number?
3.5. If there are 64 pages and the page size is 2048 words, what is the length of logical address? 3.6. A computer with a 32-bit address uses a two-level page table. Virtual addresses are split into a 9-bit top-level page table field, an 11-bit second-level page table field, and an offset. How many pages are there in the address space?
3.7. A computer with a 32-bit address uses a two-level page table. Virtual addresses are split into a 10-bit top-level page table field, an 12-bit second-level page table field, and an offset. How large are the pages?
II. Summary questions
1. What is the problem with no memory abstraction?
2. What is swapping?
3. What are the two methods of keep track of memory usages?
