Let the page fault service time be 10 ms in a computer with average memory access time being 20 ns. If one page fault is generated for every 106 memory accesses, what is the effective access time for the memory? A) 21 ns B) 30 ns C) 23 ns D) 35 ns

Official answer: B) 30 ns. Explanation: Given: - Normal memory access time, Tm = 20 ns - Page fault service time, S = 10 ms = 10 106 ns = 107 ns - Page fault rate, p = 1106 = 10-6 The effective access time (EAT) is given by: EAT = (1 - p) Tm + p S aligned EAT &= (1 - 10-6) 20 ns + 10-6 107 ns \\ & 20 ns + 10 ns \\ &= 30 ns aligned Hence, the effective access time is 30 ns, which corresponds to option (B).

Operating Systems · Memory Management and Virtual Memory

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GATE CSE 2011 Q20 · MCQ · 1 mark

Let the page fault service time be $10\text{ ms}$ in a computer with average memory access time being $20\text{ ns}$ . If one page fault is generated for every $10^6$ memory accesses, what is the effective access time for the memory?

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Memory Management and Virtual Memory

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How GATE tests Memory Management and Virtual Memory

Memory management and virtual memory is a high-yield, computation-heavy topic in GATE CS, frequently carrying 2-mark NAT and MCQ/MSQ questions. The exam heavily emphasizes multi-level page table sizing, hierarchical bit-splitting, page replacement algorithm simulation (FIFO, LRU, OPTIMAL, MRU, LIFO), and Effective Memory Access Time (EMAT) calculations involving TLBs and disk transfers. Recent years have introduced variants such as bounded lookahead optimal replacement, code-based loop/array access patterns, and TLB reach sizing.

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Operating Systems · Memory Management and Virtual Memory

Official IIT answer key · IIT Madras · Audited Aug 2026

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GATE CSE 2011 Q20 · MCQ · 1 mark

Let the page fault service time be $10\text{ ms}$ in a computer with average memory access time being $20\text{ ns}$ . If one page fault is generated for every $10^6$ memory accesses, what is the effective access time for the memory?

Select an option to check

Key concept

Memory Management and Virtual Memory

Step-by-step verified solution

Examiner trap & misconception

Topic notes

How GATE tests Memory Management and Virtual Memory

Full Memory Management and Virtual Memory guide →

More on Memory Management and Virtual Memory

All 32 questions on Memory Management and Virtual Memory →

Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

Let the page fault service time be $10\text{ ms}$ in a computer with average memory access time being $20\text{ ns}$ . If one page fault is generated for every $10^6$ memory accesses, what is the effective access time for the memory?

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Let the page fault service time be $10\text{ ms}$ in a computer with average memory access time being $20\text{ ns}$ . If one page fault is generated for every $10^6$ memory accesses, what is the effective access time for the memory?

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Let the page fault service time be 10 ms10\text{ ms}10 ms in a computer with average memory access time being 20 ns20\text{ ns}20 ns. If one page fault is generated for every 10610^6106 memory accesses, what is the effective access time for the memory?

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Let the page fault service time be 10 ms10\text{ ms}10 ms in a computer with average memory access time being 20 ns20\text{ ns}20 ns. If one page fault is generated for every 10610^6106 memory accesses, what is the effective access time for the memory?

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Let the page fault service time be $10\text{ ms}$ in a computer with average memory access time being $20\text{ ns}$ . If one page fault is generated for every $10^6$ memory accesses, what is the effective access time for the memory?

Let the page fault service time be $10\text{ ms}$ in a computer with average memory access time being $20\text{ ns}$ . If one page fault is generated for every $10^6$ memory accesses, what is the effective access time for the memory?