* Use madvise(2) as a fallback for readahead(2)
* Investigate whether readahead is an advice or command
* Investigate whether madvise can be used to evacuate pages not needed anymore
* Update model when exe or maps are deleted with no replacement
* Add the proposal and docs
* Make time tracking more realistic: track real time, and take care of
  hibernation too.
* Use Active and Inactive info from /proc/meminfo
* Figure out difference between buffers and cache. buffers are not to be
  written back to disk.  can use a good percentage of them.