Model
The five-minute rule
Keep a page resident if its re-reference interval is shorter than the break-even. Residency is an economic decision.
How it behaves
One input on the horizontal axis, the others held fixed.
Data table
| RAM price ($ per GB) | Keep in RAM if re-read within |
|---|---|
| 0.5 | 786 s |
| 0.524 | 751 s |
| 0.548 | 717 s |
| 0.574 | 685 s |
| 0.601 | 654 s |
| 0.63 | 624 s |
| 0.659 | 596 s |
| 0.69 | 569 s |
| 0.723 | 544 s |
| 0.757 | 519 s |
| 0.793 | 496 s |
| 0.83 | 474 s |
| 0.87 | 452 s |
| 0.911 | 432 s |
| 0.954 | 412 s |
| 0.999 | 394 s |
| 1.05 | 376 s |
| 1.09 | 359 s |
| 1.15 | 343 s |
| 1.2 | 327 s |
| 1.26 | 313 s |
| 1.32 | 299 s |
| 1.38 | 285 s |
| 1.44 | 272 s |
| 1.51 | 260 s |
| 1.58 | 248 s |
| 1.66 | 237 s |
| 1.74 | 226 s |
| 1.82 | 216 s |
| 1.9 | 206 s |
| 1.99 | 197 s |
| 2.09 | 188 s |
| 2.19 | 180 s |
| 2.29 | 172 s |
| 2.4 | 164 s |
| 2.51 | 157 s |
| 2.63 | 150 s |
| 2.75 | 143 s |
| 2.88 | 136 s |
| 3.02 | 130 s |
| 3.16 | 124 s |
| 3.31 | 119 s |
| 3.47 | 113 s |
| 3.63 | 108 s |
| 3.8 | 103 s |
| 3.98 | 98.7 s |
| 4.17 | 94.3 s |
| 4.37 | 90 s |
| 4.57 | 86 s |
| 4.79 | 82.1 s |
| 5.01 | 78.4 s |
| 5.25 | 74.9 s |
| 5.5 | 71.5 s |
| 5.76 | 68.3 s |
| 6.03 | 65.2 s |
| 6.32 | 62.3 s |
| 6.61 | 59.5 s |
| 6.93 | 56.8 s |
| 7.25 | 54.2 s |
| 7.59 | 51.8 s |
| 7.95 | 49.4 s |
| 8.33 | 47.2 s |
| 8.72 | 45.1 s |
| 9.13 | 43.1 s |
| 9.56 | 41.1 s |
| 10 | 39.3 s |
| 10.5 | 37.5 s |
| 11 | 35.8 s |
| 11.5 | 34.2 s |
| 12 | 32.7 s |
| 12.6 | 31.2 s |
| 13.2 | 29.8 s |
| 13.8 | 28.4 s |
| 14.5 | 27.2 s |
| 15.2 | 25.9 s |
| 15.9 | 24.8 s |
| 16.6 | 23.6 s |
| 17.4 | 22.6 s |
| 18.2 | 21.6 s |
| 19.1 | 20.6 s |
| 20 | 19.7 s |
Worked examples, recomputed
Every number the mechanisms quote for this relationship is recomputed from it, so none of them disagrees with it.
Where it appears
Each mechanism states it in its own names. The general symbol each name stands for is shown with it.
- Memory & Resource Management
Who is allowed to hold how much memory, for how long, and what happens to the work when the answer is less than it asked for?