Os presentation

A complete presentation about Page Fault in Operating Systems.

1. Page Fault

2. Daffodil International University Submitted To: Zerin Nasrin Tumpa Lecturer Daffodil International University Submitted By: Nirnay Mukharjee – 143 – 15 – 4421

3. Index Definition Reasons Page fault handling Page Replacement

4. Page Fault A  page fault error  occurs when the operating system cannot find the data in virtual memory. This usually happens when the virtual memory area, or the table that maps virtual addresses to real addresses, becomes corrupt.

5. Reasons for Page fault While page faults are common when working with virtual memory, each page fault requires transferring data from secondary memory to primary memory. This process may only take a few milliseconds, but that can still be several thousand times slower than accessing data directly from memory. Therefore, installing more system memory can increase your computer's performance, since it will need to access virtual memory less often.

6. Page fault reason So when page fault occurs then following sequence of events happens :

7. Page fault handling Most page faults are handled without any problems. However, an invalid page fault may cause a program to hang or crash. This type of page fault may occur when a program tries to access a memory address that does not exist. Some programs can handle these types of errors by finding a new memory address or relocating the data. However, if the program cannot handle the invalid page fault, it will get passed to the operating system, which may terminate the process. This can cause the program to unexpectedly quit.

8. Cont. While page faults are common when working with virtual memory, each page fault requires transferring data from secondary memory to primary memory. This process may only take a few milliseconds, but that can still be several thousand times slower than accessing data directly from memory. Therefore, installing more system memory can increase your computer's performance, since it will need to access virtual memory less often.

9. Page Replacement Prevent over‐allocation of memory by modifying page‐fault service routine to include page replacement • Use modify (dirty) bit – Reduce overhead overhead of page transfers transfers – Only modified pages are written to disk • Page replacement completes separation between logical memory and physical memory – large virtual memory can be provided on a smaller physical memory

10. Cont.

11. Thank You