In a system with very limited memory (only 2 frames) and a reference string with frequent repeated accesses to a small set of pages, which algorithm is generally better and why?

hard⚖️ Approach Comparison Q8 of Q15

Operating Systems - Page Replacement - FIFO, LRU, Optimal Algorithm

AOptimal, because it perfectly predicts future accesses and minimizes faults

BLRU, because it keeps recently used pages which are likely to be reused soon

CRandom replacement, because it avoids overhead of tracking usage

DFIFO, because its simplicity reduces overhead in constrained memory

Step-by-Step Solution

Solution:

Step 1: Consider memory constraints and access pattern
With only 2 frames and frequent repeated accesses, LRU keeps recently used pages, reducing faults. Optimal is ideal but impractical. FIFO ignores usage, causing more faults. Random is unpredictable.
Final Answer:
Option B -> Option B
Quick Check:
LRU suits small memory with locality [OK]

Quick Trick: LRU excels with small memory and locality [OK]

Common Mistakes:

MISTAKES

Assuming Optimal is always practical
Choosing FIFO for simplicity over fault rate
Ignoring benefits of usage tracking

Trap Explanation:

PITFALL

Candidates may pick Optimal ignoring practicality or FIFO ignoring fault impact.

Interviewer Note:

CONTEXT

Tests ability to apply algorithms to constrained resource scenarios.

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In a system with very limited memory (only 2 frames) and a reference string with frequent repeated accesses to a small set of pages, which algorithm is generally better and why?

Step 1: Consider memory constraints and access pattern

Final Answer:

Quick Check:

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