GATE CS 2004 Q21 — Memory Management and Virtual Memory

The correct option is A.

Explanation:

The minimum number of page frames that must be allocated to any process is determined by the Instruction Set Architecture (ISA) of the processor.

Here is why:

• For any instruction to execute successfully, all the memory pages referenced by that single instruction must reside in physical memory simultaneously.
• If we allocate fewer frames than the maximum number of pages a single instruction can reference, the process will encounter a page fault during the instruction's execution. When the missing page is brought in, it might replace one of the pages already loaded for the same instruction, leading to an infinite loop of page faults (thrashing at the instruction level) and preventing the instruction from ever completing.

Example:
Consider an instruction like ADD A, B (which adds values from memory address A and B and stores the result). To execute this instruction, we need frames for:

1. The page containing the instruction itself.
2. The page containing operand A.
3. The page containing operand B.