3D Page Replacement Visualizer

Replacement algorithm

Physical frames 6

Working-set size 9

Access speed 1.0×

Page faults

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Hit rate

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Accesses

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Frames used

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How it works

A program references pages mostly from a small "working set" (locality of reference), with occasional jumps to a new page. Each requested page is checked against the physical frame grid: if it's already resident that's a hit; otherwise it's a page fault and a victim frame must be evicted to make room.

hit rate = hits / accesses
FIFO: evict the frame loaded longest ago
LRU:  evict the frame not referenced for the longest time
LFU:  evict the frame referenced the fewest times

Physical frames — how many pages can be resident in RAM at once; fewer frames means more thrashing.
Working-set size — how many distinct pages the program cycles through; a working set larger than the frame count guarantees faults even under the best policy.
FIFO — cheap to implement, but can suffer Belady's anomaly: adding more frames can, counter-intuitively, increase faults.
LRU — tracks recency per frame; usually close to optimal because it approximates "the page least likely to be used again soon".
LFU — tracks reference frequency; strong when some pages are genuinely hot, weaker when access patterns shift over time (old hot pages linger).

Real-world relevance: this is exactly what an OS's virtual memory manager does at page-fault time — decide which resident page to swap out to disk (or drop, if it's not dirty) to load the one the CPU just asked for.

requesting –

Hit Fault / evict Incoming page

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