Menu_634641185555058750_CS4108 Operating System Lab Assignment

7/29/2019 Menu_634641185555058750_CS4108 Operating System Lab Assignment

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SEMESTER-IV

CS 4108 OPERATING SYSTEM LAB ASSIGNMENT

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING, B. I. T. MESRA

1. Write a program that will simulate FCFS, SJF, SRT (shortest remaining tine first), and round robinscheduling algorithm. For each algorithm, the program should compute waiting time, turnaround

time of every job as well as the average waiting time and the average turn around time. The

average values should be consolidated in a table for easy comparison. You may use the following

data to test your program. The time quantum for round robin is 4 ms and the context switching

time is zero.

Arrival time CPU cycle(in ms)

0 6

3 2

5 1

9 7

10 5

12 314 4

16 5

17 7

19 2

Table 1

2. Using your program1, change the context switching time to 0.4 ms. Compare outputs from both

runs and print which is a better policy.

3. Using the information give in table 2 and table 3 to complete the following program

Job list

Job stream number Time Job Size

1 5 5760

2 4 4190

3 8 3290

4 2 2030

5 2 2550

6 6 6990

7 8 8940

8 10 740

9 7 3930

10 6 6890

11 5 658012 8 3820

13 9 9140

14 10 420

15 10 220

16 7 7540

17 3 3210

18 1 1380

19 9 9850


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20 3 3610

21 7 7540

22 2 2710

23 8 8390

24 5 5950

25 10 760

Table2

Memory list

Memory Block Size

1 9500

2 7000

3 4500

4 8500

5 3000

6 9000

7 1000

8 5500

9 1500

10 500Table 3

At one large batch- processing computer installation the management wants to decide what storage

placement strategy will yield the best possible performance. The installation runs a large real storage

computer under fixed partition multiprogramming. Each user program runs in a single group of contiguousstorage locations. Users state their storage requirements and time units for CPU usage on their job control

card. The operating system allocates to each user the appropriate partition and starts up the users jobs. The

jobs remain in memory until completion. A total of 50,000 memory locations are available, divided into

block as indicated in the table above.

a. Write a event driven simulation to help you decide which storage placement strategy should be

used at this installation. Your program would use the job stream and memory partitioning as

indicate previously. Rum the program until all jobs have been executed with the memory as is (inorder by address). This will give you the first fit type performance results.

b. Sort the memory partitions by size and run the program a second time; this will give the best fit

performance results. For both parts a. and b. you are investigating the performance of the system

using a typical job stream by measuring:

(i) throughput ( how many jobs are processed per given time unit)

(ii) storage utilization (percentage of partitions never used, percentage of partitions heavily used,

etc)

(iii) waiting queue length

(iv) waiting time in queue

(v) internal fragmentation

4. Suppose your system (as explained in program 3) now has a spooler (storage area in which to

temporarily hold jobs) and the job scheduler can choose which will be served from among 25resident jobs. Suppose also that the FCFS policy is replaced with SJF policy. This would require

that a sort by time be performed on the job list before running the program. Dose this make a

difference in the results. The program should be run twice to test this new policy with both best fit

and first fit.

5. Suppose your spooler (as describe in program 4) replace the previous policy with one of

Smallest Job First Served. This should require that a sort by job size be performed on the job list

before running the program. The program should be run twice to test this new policy with both

best fit and first fit. Print the result.


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6. The following sequence of requests for program words is taken from a 460 word program:

10,11,104,170,73,309,185,245,246,434,458,364. Main memory can hold a total of 200words for

this program and the page frame size will match the size of the pages into which the program has

been divided. Calculate the page number according to the page size; divide by the page size, andthe quotient gives the page number. The number of page frames in memory is the total number,

200, divided by the page size.

a. Find the success frequency for the request list using FIFO replacement algorithm and a page size

of 100 words. (There are two page frames).

b. Find the success frequency for the request list using a FIFO replacement algorithm and a page

size of 20 words. (10 pages. 0 through 9)

c. Find the success frequency for the request list using FIFO replacement algorithm and a page sizeof 200 words.

d. Repeat a. through c. above, using a main memory of 400 words. The size of each page frame will

again correspond to the size of the page.

Optional Questions

7. Given the following information for an assembly language program:

Job size = 3126 bytes

Page size = 1042 bytesInstruction at memory location 532: LOAD 1, 2098

Instruction at memory location 1156: ADD 1, 2087Instruction at memory location 2086: SUB 1, 1052

Data at memory location 1052: 015672



a. Find the number of pages needed to store the entire job?

b. Compute the page number and displacement for each of the byte addresses where the

data is stored.c. Determine whether the page number and displacements legal for this job.

8. writ a program that will simulate the FCFS, SSTF, LOOK, and C-LOOK seek optimizationstrategies. Assume that:

a. The disks outer track is the 0 track and the disk contains 200 tracks per surface.

Each track holds 8 sectors numbered 0 through 7.

b. A seek takes 10+0.1* T ms, where T is the number of tracks of motion from one request to the

next, and 10 is movement time constant.c. One full rotation takes 8 ms.

d. Transfer time is 1ms.

Use the data in table 4 to test your program.

For comparison purposes, compute the average, variance, standard deviation of time required to

accommodate all request under each of the strategies. Consolidate your result into a table.

Arrival Time Track requested Sector requested

0 45 0

23 132 6

25 20 2

29 23 1

35 198 7

45 170 5


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57 180 3

83 78 4

88 73 5

95 150 7

Table 4

Menu_634641185555058750_CS4108 Operating System Lab Assignment

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