Page Replacement Algorithms

2. Optimal Page Replacement.
   • It is called OPT or MIN for short.
   • Such an algorithm will yield the lowest possible number of page faults and won't suffer from Belady's anomaly.
   • It turns out that such an algorithm exists: it will simply replace the page that will not be used for the longest time in the future.
   • The only problem in implementing such an algorithm is that we simple can't see the future!
   • In practice, most page-replacement algorithms try to approximate Optimal Page Replacement by predicting (estimating) in one fashion or another what page will not be used for the longest period of time.
   • This algorithm doesn't suffer from Belady's anomaly.