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Page Replacement Algorithm Simulator
ShippedAn interactive OS memory management tool comparing FIFO, LRU, and Optimal page replacement algorithms and page fault rates.
- HTML
- CSS
- JavaScript
The Problem
Page replacement feels abstract in an OS textbook. You read about FIFO, LRU, and Optimal algorithms, and the differences seem obvious on paper. But I wanted to understand why LRU is so hard to implement efficiently in practice, and why the theoretically optimal algorithm can't actually be built. There's a gap between knowing the definition of an algorithm and understanding why real systems make the tradeoffs they do.
What It Does
Architecture & How It's Built
Implemented in vanilla JavaScript with CSS grid visualization tables.
- Virtual Memory Frame State: Simulates physical RAM frames and virtual page tables.
- LRU Recency Stack: Tracks timestamp updates on memory hits.
- Look-Ahead Optimal Engine: Pre-scans future page reference strings to identify the optimal page to evict.
Decisions & Tradeoffs
- **The cost of knowledge in algorithm design**: Optimal replacement assumes future knowledge. LRU approximates it with recency tracking overhead. FIFO is cheap but inefficient.
- **Textbook simplicity vs Practical reality**: Building the tool revealed that real-world LRU is an approximation due to hardware timestamp tracking costs.
- **Vanilla Web Technologies**: Built without external frameworks for lightweight execution and immediate loading.
Roadmap & What's Next
- Adding Second-Chance (Clock) and LFU (Least Frequently Used) algorithm options.
- Visualizing thrashing under high memory contention.
Technology Stack
HTML
CSS
JavaScript
Quick Links
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