fdesc allocation optimization

[Alexey Dokuchaev]

hi there,

i've been browsing some of dfbsd resources recently, and found this one
being pretty interesting:

http://leaf.dragonflybsd.org/mailarchive/commits/2005-06/msg00526.html

however, it seemingly did not get attention in our lists.  so i am
wondering if there are work/plans on porting hsu@'s work?  i remember
that at some point we adopted some openbsd-derived algorithm, but since
matt states that this is "far better algorithm then anything we or
freebsd thought up before", i figured it worth a look.

./danfe