Main Memory Template
Assuming a 1-KB page size, indicate the page numbers and offsets for the following address references in the table below:
Address Reference Page Offset
3085
42095
215201
650000
2000001
Consider a logical address space of 256 pages with a 4-KB page size, mapped onto a physical memory of 64 frames.
How many bits are required in the logical address? Explain how you arrived at this solution.
Answer: ____________________________
Explanation:
How many bits are required in the physical address? Explain how you arrived at this solution.
Answer: ____________________________
Explanation:
Consider the following segment table:
Segment Base Length
0 219 600
1 2300 14
2 90 100
3 1327 580
4 1952 96
What are the physical addresses for the following logical addresses?
Logical Addresses Physical Addresses
0,430
1,10
2,500
3,400
4,112
Consider a paging system with the page table stored in memory.
If a memory reference takes 50 nanoseconds, how long does a paged memory reference take? Explain how you arrived at this solution.
Answer: ______________________________________________________
If we add TLBs, and 75 percent of all page-table references are found in the TLBs, what is the effective memory reference time? You must show your calculations to receive full credit.
Answer: ______________________________________________________
5. Given six memory partitions of 300 KB, 600 KB, 350 KB, 200 KB, 750 KB, and 125 KB (in order), how would the first-fit, best-fit, and worst-fit algorithms place processes of size 115 KB, 500 KB, 358 KB, 200 KB, and 375 KB ? First-fit is already done for you as an example.
a. First-fit:
115 KB is put in 300 KB partition, leaving
500 KB is put in 600 KB partition, leaving
358 KB is put in 750 KB partition, leaving
200 KB is put in 350 KB partition, leaving
375 KB is put in 392 KB partition, leaving
b. Best-fit
c. Worst-fit
d. Rank the algorithms in terms of how efficiently they use memory. Explain how and why you ranked them as you did.
6. In a minimum of 100 words, explain the difference between internal and external fragmentation.
7. In a minimum of 100 words, compare the memory organization schemes of contiguous memory allocation, pure segmentation, and pure paging with respect to the following issues:
a. External fragmentation
b. Internal fragmentation
c. Ability to share code across processes
