PPT Slide
Load Control
- The page replacement algorithms can provide useful load metrics:
- Clock algorithm - if the clock hand rate is too slow, bring in more processes; if the clock hand rate is too fast, swap out processes.
- Page fault frequency load control - track the page faults/second. Interesting choice: the “L==S” criterion. Keep the mean time between page faults (L) the same as the time it takes to handle a page fault (S). If L > S, swap processes out; if L < S, swap processes in (methinks the book has this backwards!).
- Most UNIX systems revert to swapping when the page fault rates get high. Separate daemons (pageout on xi; kswapd on Linux) perform the swapping.
-