New file descriptor allocation code in FreeBSD

[Matthew Dillon]

:FYI, the performance difference caused by this commit is very impressive on
:FreeBSD:
:
:http://people.freebsd.org/~des/fdbench/
:
:While porting this back to -STABLE and DragonFly is not trivial (many 5-ish
:calls :( ), but I think it is worthy to have a look on it :)

    I looked at it... I think it's interesting but it isn't critical right
    now.  It looks like it would be as much work to adapt subr_blist.c
    as it would just to bring in DES's stuff.

    If you would like to have a go at putting together a patch set I would
    be happy to review it.  It doesn't look like there are that many
    FreeBSD-5isms.  You won't be able to just patch it in from the 
    FreeBSD-5 diffs but doing it manually does not look too difficult.

						-Matt