This was a recent thread and I don't think it was made clear
if bufcache could be altered via sysctl or not.  If you don't
include an option for BUFCACHE at the config time, then
the default is 5 defined in kern/kern_allocsys.c ?  Wait,
its 10% of the first 2mb and 5% of the remaining

So, if I'm current built with the defaults, have 1024mb of RAM
and I see this:

There are 6553 buffers using 52424 kBytes of memory.

Total:                    5682  86       49619  94       52352  99      94

I would say that is actually 5%.  Right?

I was told that the nfsd send error 55 were due to bufcache being set too
low.  I should bump up BUFCACHE to 20 or 25 .. would that seem reasonable?