Problem 2 (Page Table Implementation 29 pts) In a paging system, the process’ sp
ID: 3813206 • Letter: P
Question
Problem 2 (Page Table Implementation 29 pts)
In a paging system, the process’ space is divided into consecutive pages of fixed length: Page 0, Page 1, Page 2, etc.
As such, a logical address (also called a virtual address) consists of:
Page #
Offset
In a paging system, main memory is divided into consecutive frames of fixed length (same length as the pages):
Frame 0, Frame 1, Frame 2, etc.
Some of the logical pages are placed in the physical frames. For example, pages 3, 8 and 10 might be placed in frames 104, 87 and 378, respectively, with the other pages of the process in virtual memory, i.e., on disk (or other form of secondary memory).
The goal of this exercise is to help you understand the Simple indexing and Multi-level indexing for converting a logical address (page number + offset) to a physical address (frame number + offset, or a page fault if the page is not in main memory):
Throughout this exercise, logical addresses and physical addresses are written as pairs of numbers (page number offset for logical addresses, frame number/offset for physical addresses).
Diagram:
Main Memory
Address Present Bit | Frame Number
0 104
1 334
2 45
3 891
4 115
… … …
256 0 333
257 0 228
258 0 610
259 0 200
260 1 324
261 1 900
262 1 1005
263 0 820
264 1 20
265 0 5
266 0 1005
267 0 220
268 1 4
269 1 303
270 1 689
271 0 446
272 1 848
273 0 666
274 1 111
275 1 229
Answer the following questions based on the above (completed) diagram.
Interrupt indicator
(2 pt) Logical 2 105 causes a page fault? Yes or No (circle one). If no, converts to physical: (2 pt) Logical 5 640 causes a page fault? Yes or No (circle one). If no, converts to physical: (2 pt) Logical 12 320 causes a page fault? Yes or No (circle one). If no, converts to physical:
Page #
Offset
Explanation / Answer
1) Logical Address:
2 105
LA = Page Number in page table + Offset
Therefor
2 number page is stored in 45 number of frame, so this is a page hit in the page table and it will translate into the below physical address.
Physical Address = Frame Number + Offset
PA = 45 105
2)LA = 5 640
Page# = 5 it is not present in the page table, so page table miss therefor page fault is occured.
3) LA = 12 320
Page# = 12, it is not present in the page table, so page table miss therefor so page fault is occured.
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