Optimal Page Replacement in OS

February 2, 2021

Optimal page replacement in OS

Optimal Page Replacement in OS

The process in an operating system occupies some dedicated memory. This memory is further divided into chunks called pages. These pages are brought from secondary memory to the primary memory as the CPU demands them. This method is known as page swapping and is done through an algorithm.

To fulfill the demand of the most frequently used pages, the operating systems keep these pages in the primary memory. Pages that not have been used since a long time are replaced with the most frequently used pages under the method called as Optimal Page Replacement technique.
The approach can be best explained by the below reference string and the frame size.

                                                 optimal page replacement

The diagrammatic representation above states the order in which the stack will be filled as per the demands in the primary memory. In the case of a page fault, the least recently used page is replaced with the pager which in immediate demand.

Algorithm for Optimal Page Replacement

Step 1: Push the first page in the stack as per the memory demand.

Step 2: Push the second page as per the memory demand.

Step 3: Push the third page until the memory is full.

Step 4: As the queue is full, the page which is least recently used is popped.

Step 5: repeat step 4 until the page demand continues and until the processing is over.

Step 6: Terminate the program.

Operating systems Memory

      Read More

  1. Memory Management Introduction
  2. Partition Allocation Method
    1. First Fit in OS
      1. Program in C | C++ | Java | Python
    2. Best fit
      1. Program in C | C++ | Java | Python
    3. Worst fit
      1. Program in C | C++ | Java | Python
    4. Next fit
      1. Program in C | C++ | Java | Python
    5. First fit best fit worst fit in OS Example
  3. Buddy- System Allocator
  4. Paging
    1. Types of Paging
  5. Fragmentation
    1. internal fragmentation
    2. external fragmentation
    3. internal fragmentation vs external fragmentation
  6. Mapping Virtual address to Physical Address.
  7. Virtual Memory 
  8. Demand Paging
  9. Implementation of Demand paging and page fault
  10. Segmentation
  11. Page Replacement Algorithms
    1. LRU
    2. FIFO
    3. Optimal Page Replacement algorithm
  12. Thrashing
  13. Belady’s Anomaly
  14. Static vs Dynamic Loading
  15. Static vs Dynamic Linking
  16. Swapping
  17. Translational Look Aside Buffer
  18. Process Address Space
  19. Difference between Segmentation and Paging
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