Consider the following disc Queue with requests for I/O to block on cylinders:…
2025
Consider the following disc Queue with requests for I/O to block on cylinders:
45, 81, 185, 33, 175, 99, 150, 77
(Consider that the head starts from location 58)
What will be the total head movement of cylinders for the SSTF disc Scheduling technique?
Answer: C. 177 — Solution (SSTF): Start at head position 58 and always serve the nearest pending request. 58 → 45 (distance 13). Cumulative = 13. 45 → 33 (distance 12).…
- A.
160
- B.
124
- C.
177
- D.
240
Attempted by 126 students.
Show answer & explanation
Correct answer: C
Solution (SSTF): Start at head position 58 and always serve the nearest pending request.
58 → 45 (distance 13). Cumulative = 13.
45 → 33 (distance 12). Cumulative = 25.
33 → 77 (distance 44). Cumulative = 69.
77 → 81 (distance 4). Cumulative = 73.
81 → 99 (distance 18). Cumulative = 91.
99 → 150 (distance 51). Cumulative = 142.
150 → 175 (distance 25). Cumulative = 167.
175 → 185 (distance 10). Cumulative = 177.
Total head movement: 177 cylinders.
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