ISRO CSE 2014 | Question: 70

Question

Dirty bit is used to indicate which of the following?

• A. A page fault has occurred
• B. A page has corrupted data
• C. A page has been modified after being loaded into cache
• D. An illegal access of page

Comments

C IS ANSWER

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C IS ANSWER

A DIRTY BIT REPLACE OF NEW BLOCK IN THE CACHE MWMWORY AND THAT REPLACED BLOCK IS KEPT  IN THE MAIN MEMORY

Answer 1

Answer : A page has been modified after being loaded into cache Because

When a bit is modified by the CPU and not written back to the storage, it is called as a dirty bit. This bit is present in the memory cache or the virtual storage space.A dirty bit is a flag that indicates whether an attribute needs to be updated. Such situations usually occur when a bit in a memory cache or virtual memory page that has been changed by a processor but has not been updated in the storage.

Answer 2

A dirty bit or modify  bit is a bit that is associated with a block of computer memory and indicates whether or not the corresponding block of memory has been modified.The dirty bit is set when the processor writes to (modifies) this memory. The bit indicates that its associated block of memory has been modified and has not yet been saved  to storage.When a block of memory is to be replaced, its corresponding dirty bit is checked to see if the block needs to be written back to secondary memory before being replaced or if it can simply be removed. Dirty bits are used by the CPU cache and in the page replacement algorithm of an operation system.

Hence,Option(C)A page has been modified after being loaded into cache.

Answer 3

Option C will be correct option for it

1. A page has been modified after being loaded into cache
2. Dirty bit is used for write back policy.

Answer 4

C is the Answere as Dirty bit says, whether a page has been modified or not.