Online (Page Replacements)
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Description
When page fault occurs during the program execution, operating systems use page replacement algorithms to select a victim page from primary memory and makes room for the required page.
Related Problems
Related: Offline
Parameters
$n$: number of page requests
$k$: number of pages able to fit in cache
Table of Algorithms
| Name | Year | Time | Space | Approximation Factor | Model | Reference |
|---|---|---|---|---|---|---|
| Not recently used | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| First-in, first-out | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| Second-chance | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| Clock | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| Least recently used | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| Random | 1940 | $O(n)$ | $O(k)$? | Exact | Randomized | |
| Not frequently used (NFU) | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| Aging | 1940 | $O(nk)$? | $O(k)$ | Exact | Deterministic | |
| Longest distance first (LDF) page replacement algorithm | 2017 | $O(nk)$? | $O(k)$ | Exact | Deterministic | Time |
Time Complexity Graph
Space Complexity Graph
Time-Space Tradeoff
