Title
Information and Control in Gray-Box Systems

Author
Andrea and Remzi Arpaci-Dusseau

Location
SOSP

Date
2001

The authors develop a mechanism to infer information about the state
of the underlying OS, treating it as neither a black- or white-box,
but as a grey-box.  They believe that a challenge to OS research is to
disseminate OS research ideas without requiring any changes to the
underlying OS.  They develop and investigate three gray-box
"Information and Control Layers" (ICLs) for determining the contents
of the file cache, controlling the layout of files across local disk,
and limiting process execution based on available memory.

Gray-Box Suites:
1) File cache content detector (FCCD) allows applications to reorder
file operations to first access data already in the cache.
Experiments show that operations on grep and a fastsort achieve three
times the performance as without these hints.
2) File Layout Detector and Controller (FCCD) which controls layout of
file blocks on disk, essentially via recreation of files in new
directories, with small files first.  Assumes FFS structure.
3) Memory-based admission controller (MAC) which prevents malloc from
working when it would force swaps.

They aim to eventually produce a grey-box toolkit.

On reading the paper, I just did not understand how the FCCD cannot
trigger what they call the "Heisenburg effect" more often.  The ICLs
seem that they would greatly modify---not just observe---the system
they are running on.