John,

Thanks for the several clarifications to Simon Burge and myself.
While this definitely not my area of research interest, I appreciate
the numbers even more with the extra details about exactly what is
being measured.

Some of the questions which could easily be misunderstood as hostile
disbeleif, rather than trying to understand precisely what was being
reported.  Thanks especially for answering those factually.

(Yes, btw, I knew the merged buffer cache goes back some years, but as
you know, that wasnt really the point of my analogy. Other changes
matter, too:).

I havent tried it personally, but several of my coulleages in the DSG
research group here have toyed with tuning Linux compilation. They
find that when the total of GCC's code and data, plus the source code,
exceeds total RAM, then the machine thrashes.  I've seen a seen
similar phenomenon with older SunOS versions (4.1.1 through 4.1.3.  or
thereabouts). I dont know for sure, but I'd conjecture the split
buffer cache/VM might do better than a unified one under these
conditions.   All food for thought.