At Coda accesses the console fills with kernel messages (in green)
  "coda_inactive: 0xNNNNNNNN usecount 1"
  seemingly once per Coda file being accessed for the first time
  (per new cache entry?) I assume this to be just informational.

yes, just informational as I was attempting to track something else
down.  I think usecount is expected to be 1 when coda_inactive is
called, and I have updated what will be NetBSD 6 to not print if it's 1.

So, I did:

for i in `seq 1 1500`; do file=`printf "%04d" $i`; touch $file; done

and saw 2986 CML entries pending.  But ls|wc gets me 1500.
This is with coda-6.9.5 from pkgsc on NetBSD 5.1_STABLE.

I dimly recall the directory issue is alignment and skipping over the
end of 4K pages or some such.  So I did:

for i in `seq 1 1000`; do file=really-long-file-name-trying-overflow-`printf "%04d" $i`; touch $file; done

and then ls|wc gets only 220.

I'm really unclear on how this is supposed to work.  Questions?

1) Does coda have a directory format?  Or are directories all in
metadata and synthesized?

2) When you open a directory, does venus synthesize content from some
other format?  What format is it targetting?

3) On an operating system, people generally should be using readdir(),
it seems.   How does readdir() in the coda vfs implementation work?