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GATE 2020 CS – Question 21

Operating System · Memory Management and Virtual Memory · 1 mark · Multiple choice

Consider allocation of memory to a new process. Assume that none of the existing holes in the memory will exactly fit the process's memory requirement. Hence, a new hole of smaller size will be created if allocation is made in any of the existing holes. Which one of the following statements is TRUE?

  1. The hole created by first fit is always larger than the hole created by next fit.
  2. The hole created by worst fit is always larger than the hole created by first fit.
  3. The hole created by best fit is never larger than the hole created by first fit.
  4. The hole created by next fit is never larger than the hole created by best fit.

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Show answer and explanation

Correct answer: (C) The hole created by best fit is never larger than the hole created by first fit.

Explanation

Best fit picks the smallest hole that fits, so the leftover is the minimum possible and cannot exceed the leftover from first fit. The other statements fail on counterexamples (e.g. first fit may pick the same hole as worst or next fit).