Dirty bit is used to identify which of the following?

Correct option is A

The dirty bit is a flag used in paging to indicate whether a page in memory has been modified since it was loaded. If the dirty bit is set, the page must be written back to disk before it can be replaced or swapped out. This ensures that no data is lost when the page is evicted.
Important Key Points:
1. Dirty bits help optimize the paging process by avoiding unnecessary writes of unmodified pages to the disk.
2. When a page with a dirty bit is replaced, the operating system ensures the updated data is saved to disk.
3. Dirty bits are essential for maintaining data consistency in virtual memory systems.
Knowledge Booster:
· Pages that are currently in use in memory: Pages in use are identified using reference bits, not dirty bits.
· Pages that are swapped out to disk: Pages swapped out to disk are tracked using page tables, not dirty bits.
· Pages that are read-only in memory: Read-only pages do not involve dirty bits as they are not modified.
· Pages that are not loaded in memory: Pages not loaded in memory are not relevant to the dirty bit mechanism.