Advanced Memory Management & Virtual Memory

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Arjit Sharma
02 Mins

As modern applications demand large memory resources, operating systems use advanced techniques like virtual memory and page replacement strategies to efficiently manage memory.

Virtual Memory

Virtual memory extends physical RAM using disk space, allowing processes to execute even if their memory requirements exceed available RAM.

How Virtual Memory Works

  • The OS swaps inactive data to disk while keeping active pages in RAM.
  • This creates an illusion of unlimited memory for running applications.

Example: Running Multiple Applications

If you open a web browser, a game, and a code editor, virtual memory ensures each application gets the required space, even if RAM alone cannot hold everything.

Page Replacement Algorithms

When RAM runs out, the OS must decide which memory pages to remove and swap with new ones.

1. FIFO (First-In, First-Out)

  • Removes the oldest loaded page first.
  • Example: Works like a queue—imagine replacing the oldest document in a stack with a new one.

2. LRU (Least Recently Used)

  • Removes the least recently accessed page.
  • Example: If you haven’t visited a tab in hours, the browser may swap it out from RAM.

3. Optimal Page Replacement

  • Predicts future page accesses and removes the one least needed.
  • Example: Ideal but impractical—similar to predicting which app you won’t use next.

Thrashing

Thrashing happens when excessive page swapping slows down the system instead of speeding it up.

Causes of Thrashing

  • Too many processes competing for limited RAM.
  • Frequent swapping between disk and memory.

Solution: Working Set Model

  • Ensures each process gets enough memory to function properly.
  • Limits excessive swapping, improving system performance.

Conclusion

Advanced memory techniques like virtual memory, paging, and thrashing prevention ensure efficient multitasking, balancing performance with resource allocation. Mastering these concepts helps in debugging slow systems, optimizing applications, and designing scalable computing solutions.

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