PERFORCE change 126488 for review

[Kip Macy]

On 9/17/07, Andre Oppermann <andre at freebsd.org> wrote:
> Kip Macy wrote:
> > http://perforce.freebsd.org/chv.cgi?CH=126488
> >
> > Change 126488 by kmacy at kmacy_home:ethng on 2007/09/16 21:57:27
> >
> >       add a route structure to the inpcb
> >       release the reference to the rt_entry if its set when we free the inpcb
>
> We already had this once before and it was nasty as you had to
> do a full inpcb walk to nuke any references if a route changed.

Nope. If you keep a generation counter for the route in the inpcb and
check it each time in udp_output against the rtentry / route table
you'll know that your cached route is no longer valid. I'm not
currently doing that, but it won't be hard to add.

In any event, incurring a 20% slowdown (in the uncontended case, its
basically crippling in the contended case i.e. 1 flow on the same
route) for an event that occurs < .01% of the time on most networks
seems questionable.

 -Kip