FIFO keeps pages in arrival order and selects the oldest resident page as the victim.
It is simple but ignores how recently or frequently a page has been used.
Correct Answer: B. Under some algorithms such as FIFO, adding frames can increase the number of page faults
Explanation:
Belady's anomaly shows that fault count is not always monotonic with frame count for non-stack algorithms.
FIFO is the classic example that may fault more after receiving additional frames.
The optimal algorithm uses perfect knowledge of future references to choose the best victim.
It is not implementable online but serves as a benchmark for other algorithms.
LRU uses recent past behavior as an estimate of near-future use.
Accurate implementation requires timestamps, counters, stack ordering, or hardware-assisted approximations.
Correct Answer: A. It skips a page with a set reference bit and clears the bit before reconsidering it later
Explanation:
Second chance uses the reference bit to avoid immediately removing a recently accessed page.
Pages with no recent reference remain candidates in approximate FIFO order.
Correct Answer: B. The next page-table entry to examine as a possible victim
Explanation:
Clock arranges candidate frames conceptually in a circle and scans them using a pointer.
Referenced pages receive another chance while unreferenced pages can be selected.
Correct Answer: D. Programs tend to exhibit locality of reference
Explanation:
Locality means a program repeatedly accesses a relatively small set of nearby instructions and data for a period.
Keeping that working region in memory avoids faults on most references.
Copy-on-write delays physical duplication until a process attempts to modify a shared page.
This reduces fork time and memory use when many pages remain unchanged or exec follows soon.
Correct Answer: B. Providing a newly allocated page initialized with zeros when it is first needed
Explanation:
Zero-fill-on-demand creates a clean page without reading old contents from a file or swap area.
It also prevents a process from seeing data left by a previous memory owner.
Correct Answer: C. A memory-management technique that lets a process execute without all of its address space being in physical memory
Explanation:
Virtual memory separates the process's logical address space from the amount of installed physical memory.
Only the currently needed portions must be resident, allowing larger programs and more multiprogramming.
Correct Answer: D. Loading a page into memory only when it is first referenced
Explanation:
Demand paging postpones page loading until an actual access requires the page.
Unused pages therefore consume neither initial I/O time nor physical frames.
Correct Answer: A. To bring required pages from backing storage into memory and manage page movement
Explanation:
The pager handles page-in and page-out operations for virtual memory.
It is more precise than treating every memory transfer as whole-process swapping.
