First Come First Serve MCQ Quiz - Objective Question with Answer for First Come First Serve - Download Free PDF
Last updated on Mar 10, 2025
Latest First Come First Serve MCQ Objective Questions
First Come First Serve Question 1:
How does the number of page frames affect the number of page faults for a given memory access pattern in FIFO page replacement algorithm?
Answer (Detailed Solution Below)
First Come First Serve Question 1 Detailed Solution
The correct answer is Option 2.Key Points
- In the context of the FIFO (First-In-First-Out) page replacement algorithm, the number of page faults is influenced by the number of page frames available.
- Increasing the number of page frames generally leads to a reduction in the number of page faults because more pages can be held in memory at the same time.
- However, in some scenarios, known as Belady's anomaly, increasing the number of page frames can paradoxically increase the number of page faults.
Additional Information
- Belady's Anomaly: This phenomenon occurs in the FIFO page replacement algorithm where the number of page faults can increase as the number of page frames increases. This is counterintuitive because one would expect more page frames to always decrease page faults.
- Belady's anomaly does not occur with all page replacement algorithms; for example, it does not occur with the LRU (Least Recently Used) or OPT (Optimal) page replacement algorithms.
- It is important to analyze the specific memory access pattern to determine how the number of page frames will affect the number of page faults.
Therefore, the correct answer is that increasing the number of page frames may increase or decrease the number of page faults depending on the memory access pattern.
First Come First Serve Question 2:
If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 100.
Answer (Detailed Solution Below)
First Come First Serve Question 2 Detailed Solution
Concepts:
Sequence: 98, 37, 14, 124, 65, 100
Algorithm: First Come First Serve(FCFS)
Head is at cylinder: 32
Diagram:
Calculation:
Total Head movements= (98 32) + (98 37) + (37 14) + (124 14) + (124 65) + (100 65)
Total Head movements to serve all request = 66 + 61 + 23 + 110 + 59 + 35 = 354
First Come First Serve Question 3:
If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 100.
Answer (Detailed Solution Below)
First Come First Serve Question 3 Detailed Solution
Concepts:
Sequence: 98, 37, 14, 124, 65, 100
Algorithm: First Come First Serve(FCFS)
Head is at cylinder: 32
Diagram:
Calculation:
Total Head movements= (98 - 32) + (98 - 37) + (37 - 14) + (124 - 14) + (124 - 65) + (100 - 65)
Total Head movements to serve all request = 66 + 61 + 23 + 110 + 59 + 35 = 354
First Come First Serve Question 4:
Disk requests come to a disk driver for cylinders in the order 11, 23, 21, 3, 41, x, 25, and 39, at a time when the disk drive is reading from cylinder 15. The seek time is 4 ms/cylinder. The total seek time, if the disk arm scheduling algorithm is first-come-first-served is 560 ms. What is/are the value of x?
Answer (Detailed Solution Below)
First Come First Serve Question 4 Detailed Solution
Data:
Seek time = t = 4 ms per cylinder
Head = 15
Concept:
Since it is a first-come-first-serve scheduling request will be served in the given sequence:
11, 23, 21, 3, 41, x, 25 and 39
Diagram
Formula:
Total Seek time = total head movement × t
Calculation:
560 = total head movement × 4
total head movement = 140
Total head movement
= (15 - 11) + (23 - 11) + (23 - 21) + (21 - 3) + (41 - 3) + |41 - x| + |25 - x| + (39 - 25) = 140
= 4 + 12 + 2 + 18 + 38 + |41 - x| + |25 - x| + 14 = 140
= 88 + |41 - x| + |25 - x| = 140
= |41 - x| + |25 - x| = 52
Case 1:
66 - 2x = 52
∴ x = 7
Case 2:
2x - 66 = 52
∴ x = 59First Come First Serve Question 5:
Disk requests come to a disk driver for cylinders in the order 10, 22, 20, 2, 40, 6 and 38, at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms/cylinder. The total seek time, if the disk arm scheduling algorithms is first-come-first-served is
Answer (Detailed Solution Below)
First Come First Serve Question 5 Detailed Solution
Data:
Seek time = t = 6 ms per cylinder
Head = 20
Concept:
Since, it is a first-come-first-serve scheduling requests will be served in the given sequence:
10, 22, 20, 2, 40, 6 and 38
Diagram
Formula:
Total Seek time = total head movement × t
Calculation:
Total head movement = (20 - 10) + (22 - 10) + (22 - 2) + (40 - 2) + (40 - 6) + (38 - 6) =
= 10 + 12 + 20 + 38 + 34 + 32 = 146
Total Seek time = 146 × 6 = 876 ms.Top First Come First Serve MCQ Objective Questions
Disk requests come to a disk driver for cylinders in the order 10, 22, 20, 2, 40, 6 and 38, at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms/cylinder. The total seek time, if the disk arm scheduling algorithms is first-come-first-served is
Answer (Detailed Solution Below)
First Come First Serve Question 6 Detailed Solution
Download Solution PDFData:
Seek time = t = 6 ms per cylinder
Head = 20
Concept:
Since, it is a first-come-first-serve scheduling requests will be served in the given sequence:
10, 22, 20, 2, 40, 6 and 38
Diagram
Formula:
Total Seek time = total head movement × t
Calculation:
Total head movement = (20 - 10) + (22 - 10) + (22 - 2) + (40 - 2) + (40 - 6) + (38 - 6) =
= 10 + 12 + 20 + 38 + 34 + 32 = 146
Total Seek time = 146 × 6 = 876 ms.First Come First Serve Question 7:
Disk requests come to disk driver for cylinders 10, 153, 34, 90, 120, 205, 319, 256 and 400 in that order at a time when the disk drive is reading from cylinder 99. The cylinders are numbered from 0 to 499. Compute the total head movement incurred while servicing these requests if the disk arm scheduling algorithm is first-come-first-serve.
Answer (Detailed Solution Below) 843
First Come First Serve Question 7 Detailed Solution
Concept:
Since, it is a First-Come-First-Serve scheduling requests will be served in the given sequence:
99, 10, 153, 34, 90, 120, 205, 319, 256, 400
Diagram
Calculation:
Total head movement = (99 - 10) + (153 - 10) + (153 - 34) + (90 - 34) + (120 - 90) + (205 - 120) + (319 - 205) + (319 - 256) + (400 - 256)
= 89 + 143 + 119 + 56 + 30 + 85 + 114 + 63 + 144
= 843First Come First Serve Question 8:
Disk requests come to a disk driver for cylinders in the order 11, 23, 21, 3, 41, x, 25 and 39, at a time when the disk drive is reading from cylinder 15. The seek time is 4 ms/cylinder. The total seek time, if the disk arm scheduling algorithms is first-come-first-served is 560 ms. If the value of x is greater than 10 then what is the value of x?
Answer (Detailed Solution Below) 59
First Come First Serve Question 8 Detailed Solution
Data:
Seek time = t = 4 ms per cylinder
Head = 15
Concept:
Since it is a first-come-first-serve scheduling request will be served in the given sequence:
11, 23, 21, 3, 41, x, 25 and 39
Diagram
Formula:
Total Seek time = total head movement × t
Calculation:
560 = total head movement × 4
total head movement = 140
Total head movement
= (15 - 11) + (23 - 11) + (23 - 21) + (21 - 3) + (41 - 3) + |41 - x| + |25 - x| + (39 - 25) = 140
= 4 + 12 + 2 + 18 + 38 + |41 - x| + |25 - x| + 14 = 140
= 88 + |41 - x| + |25 - x| = 140
= |41 - x| + |25 - x| = 52
Case 1:
66 - 2x = 52
∴ x = 7
Case 2:
2x - 66 = 52
∴ x = 59First Come First Serve Question 9:
If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 100.
Answer (Detailed Solution Below)
First Come First Serve Question 9 Detailed Solution
Concepts:
Sequence: 98, 37, 14, 124, 65, 100
Algorithm: First Come First Serve(FCFS)
Head is at cylinder: 32
Diagram:
Calculation:
Total Head movements= (98 32) + (98 37) + (37 14) + (124 14) + (124 65) + (100 65)
Total Head movements to serve all request = 66 + 61 + 23 + 110 + 59 + 35 = 354
First Come First Serve Question 10:
Disk requests come to a disk driver for cylinders in the order 11, 23, 21, 3, 41, x, 25, and 39, at a time when the disk drive is reading from cylinder 15. The seek time is 4 ms/cylinder. The total seek time, if the disk arm scheduling algorithm is first-come-first-served is 560 ms. What is/are the value of x?
Answer (Detailed Solution Below)
First Come First Serve Question 10 Detailed Solution
Data:
Seek time = t = 4 ms per cylinder
Head = 15
Concept:
Since it is a first-come-first-serve scheduling request will be served in the given sequence:
11, 23, 21, 3, 41, x, 25 and 39
Diagram
Formula:
Total Seek time = total head movement × t
Calculation:
560 = total head movement × 4
total head movement = 140
Total head movement
= (15 - 11) + (23 - 11) + (23 - 21) + (21 - 3) + (41 - 3) + |41 - x| + |25 - x| + (39 - 25) = 140
= 4 + 12 + 2 + 18 + 38 + |41 - x| + |25 - x| + 14 = 140
= 88 + |41 - x| + |25 - x| = 140
= |41 - x| + |25 - x| = 52
Case 1:
66 - 2x = 52
∴ x = 7
Case 2:
2x - 66 = 52
∴ x = 59First Come First Serve Question 11:
If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 100.
Answer (Detailed Solution Below)
First Come First Serve Question 11 Detailed Solution
Concepts:
Sequence: 98, 37, 14, 124, 65, 100
Algorithm: First Come First Serve(FCFS)
Head is at cylinder: 32
Diagram:
Calculation:
Total Head movements= (98 - 32) + (98 - 37) + (37 - 14) + (124 - 14) + (124 - 65) + (100 - 65)
Total Head movements to serve all request = 66 + 61 + 23 + 110 + 59 + 35 = 354
First Come First Serve Question 12:
How does the number of page frames affect the number of page faults for a given memory access pattern in FIFO page replacement algorithm?
Answer (Detailed Solution Below)
First Come First Serve Question 12 Detailed Solution
The correct answer is Option 2.Key Points
- In the context of the FIFO (First-In-First-Out) page replacement algorithm, the number of page faults is influenced by the number of page frames available.
- Increasing the number of page frames generally leads to a reduction in the number of page faults because more pages can be held in memory at the same time.
- However, in some scenarios, known as Belady's anomaly, increasing the number of page frames can paradoxically increase the number of page faults.
Additional Information
- Belady's Anomaly: This phenomenon occurs in the FIFO page replacement algorithm where the number of page faults can increase as the number of page frames increases. This is counterintuitive because one would expect more page frames to always decrease page faults.
- Belady's anomaly does not occur with all page replacement algorithms; for example, it does not occur with the LRU (Least Recently Used) or OPT (Optimal) page replacement algorithms.
- It is important to analyze the specific memory access pattern to determine how the number of page frames will affect the number of page faults.
Therefore, the correct answer is that increasing the number of page frames may increase or decrease the number of page faults depending on the memory access pattern.
First Come First Serve Question 13:
Disk requests come to a disk driver for cylinders in the order 10, 22, 20, 2, 40, 6 and 38, at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms/cylinder. The total seek time, if the disk arm scheduling algorithms is first-come-first-served is
Answer (Detailed Solution Below)
First Come First Serve Question 13 Detailed Solution
Data:
Seek time = t = 6 ms per cylinder
Head = 20
Concept:
Since, it is a first-come-first-serve scheduling requests will be served in the given sequence:
10, 22, 20, 2, 40, 6 and 38
Diagram
Formula:
Total Seek time = total head movement × t
Calculation:
Total head movement = (20 - 10) + (22 - 10) + (22 - 2) + (40 - 2) + (40 - 6) + (38 - 6) =
= 10 + 12 + 20 + 38 + 34 + 32 = 146
Total Seek time = 146 × 6 = 876 ms.First Come First Serve Question 14:
If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 100.
Answer (Detailed Solution Below)
First Come First Serve Question 14 Detailed Solution
Concepts:
Sequence: 98, 37, 14, 124, 65, 100
Algorithm: First Come First Serve(FCFS)
Head is at cylinder: 32
Diagram:
Calculation:
Total Head movements= (98 - 32) + (98 - 37) + (37 - 14) + (124 - 14) + (124 - 65) + (100 - 65)
Total Head movements to serve all request = 66 + 61 + 23 + 110 + 59 + 35 = 354
First Come First Serve Question 15:
Consider a disk system with 100 cylinders. The requests to access the cylinders occur in the following sequence:
16, 24, 7, 9, 25, 11, 8, 87
Assuming that the head is currently at cylinder 58, what is the time taken (in ms) to satisfy all requests if first come first serve policy is used?
Answer (Detailed Solution Below) 181
First Come First Serve Question 15 Detailed Solution
(58 – 16) + (24 - 16) + (24 - 7) + (9 - 7) + (25 - 9) + (25 - 11) + (11 - 8) + (87 - 8)
= 42 + 8 + 17 + 2 + 16 + 14 + 3 + 79
= 181 ms