Project description
1) Another placement algorithm for dynamic partitioning is referred to as worst-fit. In this case, the largest free block of memory is used for bringing in a process.
a. Discuss the pros and cons of this method compared to first-, next-, and best-fit.
b. What is the average length of the search for worst-fit?
2) During the course of execution of a program, the processor will increment the con-tents of the instruction register (program counter) by one word after each instruction fetch, but will alter the contents of that register if it encounters a branch or call instruction that causes execution to continue elsewhere in the program.
Now consider Figure 7.8. There are two alternatives with respect to instruction addresses:
- Maintain a relative address in the instruction register and do the dynamic address translation using the instruction register as input. When a successful branch or call is encountered, the relative address generated by that branch or call is loaded into the instruction register.
- Maintain an absolute address in the instruction register. When a successful branch or call is encountered, dynamic address translation is employed, with the results stored in the instruction register. Which approach is preferable?
3) Consider the following string of page references 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2.Complete a figure similar to Figure 8.14, showing the frame allocation for:
a. FIFO (first-in-first-out)
b. LRU (least recently used)
c. Clock
d. Optimal (assume the page reference string continues with 1, 2, 0, 1, 7, 0, 1)
e. List the total number of page faults and the miss rate for each policy. Count page faults only after all frames have been initialized.
4) In the VAX, user page tables are located at virtual addresses in the system space. What is the advantage of having user page tables in virtual rather than main memory? What is the disadvantage?