GATE CSE 2004 | Question: 21, ISRO2007-44

Question

The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by

• A. the instruction set architecture
• B. page size
• C. number of processes in memory
• D. physical memory size

Comments

Thank you

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In question they asked : "The minimum number of page frames...". Please correct it.
https://stackoverflow.com/questions/11213013/minimum-page-frames
 

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Why not C?

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youtube Explanation :-

https://youtu.be/8wpWj89mu4Y?t=2876

Answer 1

Its instruction set architecture .if you have no indirect addressing then you need at least two pages in physical memory. One for instruction (code part) and another for if the data references memory.if there is one level of indirection then you will need at least three pages one for the instruction(code) and another two for the indirect addressing. If there three indirection then minimum $4$ frames are allocated.

http://stackoverflow.com/questions/11213013/minimum-page-frames

Comments

The minimum number of page frames is decided by Instruction Set Architecture whereas the maximum number of page frames is decided by Physical Memory Size.

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please explain why option B and C is not true.

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Hi @Parth Shah Could you please explain how maximum number of page frames is defined by physical memory size?

Answer 2

The minimum number of page frames that must be dedicated for a process is determined by Instruction set architecture.

Suppose that a instruction requires 4 pages to run till completion. Eg: it mat require 1 page for code segment, 2 pages for storing data operands and 1 page for storing stack segment. Now if we allocate only 3 pages that means only 3 pages will be present in the main memory at a time, say we didn't provide a page for stack. Then code has been executed, operand has been fetched but when we try to store the result we get a page fault. So when we get a page fault during execution the instruction has to be started again. So instruction set determines the minimum page frame.

Answer 3

A is the answer of this question, b,c,d options don't make a sense

https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/9_VirtualMemory.html

Comments

Please explain your answer in detail.

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@Manu Thakur, please don't say option D doesn't make sense...it actually determines MAXIMUM no. of frames allocation..

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@Abbas @Arjun Sir @Sachin Mittal 1 SIr should’nt page size also play a role in determining maximum number of frames because if a page size is small then we can have more number of frames compared to when page size is large for same physical memory size .

Answer 4

Answer A

The minimum number of page frames that must be allocated to a running process  is determined by the instruction set architecture

Simple instructions may need less number of frames

complex instruction or multiple level indirect operands may demand many more pages

Comments

why indirect operands require more pages?

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@Arjun Sir

Because indirect addressing requires effective address calculation and the actual operand may be present on other pages.