Page Fault Frequency
PFF is a variable space algorithm that uses a more ad hoc approach.
Basic idea:
- monitor the fault rate for each process
- if the fault rate is above a high threshold, give it more memory
- should fault less
- but it doesn’t always
- if the rate is below a low threshold, take away memory
- should fault more
- but it doesn’t always
Hard to tell between changes in locality and changes in size of working set.