>
> Now I don't have much idea on what algorithm to use, neither
> how to implement it. Probably something like the process scheduler, but
> for I/O, processes doing a lot of I/O having their I/O priority lowered.

that would be nice but another idea:

1)add something like page priority (if it doesn't already exist). lower
priority are freed first.

2) keep I/O priority for each FILE HANDLE, set it to maximum at file
open/create

3) lseek should reset it to maximum

4) every read/write should lower it proportionally to request size, unless
it's already lowest possible.



this way we would get random accessed large files (like databases) and
lots of small files well cached, while huge linearly accessed files
uncached.


priority should be counted by file handle, not process ID as same process
could use both random access for one thing and linear for another (like
sendmail with it's qf and df files).