How does Demand Paging work in an Operating System?
This question probes the mechanism of loading pages into memory only when needed. It tests knowledge of virtual memory management and page faults.
Why Interviewers Ask This
Demand paging is central to efficient memory management in large-scale systems. Interviewers ask this to verify if you understand how OS handles limited RAM efficiently. It demonstrates your ability to optimize application performance by minimizing unnecessary disk I/O.
How to Answer This Question
Explain the basic concept of lazy loading pages. Describe the page fault mechanism when a page is missing. Discuss the role of the page table and TLB. Mention replacement algorithms like LRU used when memory is full.
Key Points to Cover
- Lazy loading concept
- Page fault handling
- Page table structure
- Replacement algorithms
Sample Answer
Demand paging loads pages into physical memory only when a process references them, rather than loading the entire program at once. When a reference is made to a non-resident page, a page fault occurs, triggering the OS…
Common Mistakes to Avoid
- Confusing swapping with paging
- Omitting page fault details
- Ignoring eviction policies
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