[K42-discussion] control flags for ReAIM benchmark

[Dilma DaSilva]

 > Dilma will have to remind us of what the SMALL_FILE_OPT flag is good for.
 > 

For small files that are being used for a single client, we avoid the
costs of setting up a kernel FR object and binding the area in the
kernel with some area in the application space; instead, file content
is kept at the application (by the FileLinuxFile objects) and when the 
file is closed we keep the content in the ServerFile object that
resides in the file system address space. 

We experimented with this optimization up to a few pages (something
like four).

Unfortunately, this optimization is a non-op now, because it requires
support for non-shared files, which broke a long time ago (meaning, a
race condition started to appear) and I never got to fix it. (I'm sure 
I'll get to do that one day ... before I retire in the next 3
decades). If anyone  in the list in interested in revisting these
optimizations, replacing the current broken - and complex - 
code, I would love to be involved!

Summary: SMALL_FILE_OPT is not active, regardless of what we do with
the flag.

Dilma