On Mon, 1 Nov 2004 11:58:23 +0200
Michael Vittrup Larsen <michael.vittrup.larsen@xxxxxxxxxxxx> wrote:
> On Friday 29 October 2004 19:28, Stephen Hemminger wrote:
> > Provide port randomization for incoming connections using variation of
> > existing sequence number hash. Replace tcp_portalloc_lock and
> > tcp_port_rover with atomic operation to allow better parallelism.
> > This is based on
> > http://www.ietf.org/internet-drafts/draft-larsen-tsvwg-port-randomisation-0
> >0.txt (with confirmation of of no IPR issues).
> I have looked through this, and have a few comments:
> * It is probably a good strategy to set 'tcp_rover_next' such that
> the next search is resumed from the previous port found to be free.
> (similar to the old algorithm). I don't see this in your patch,
> but of course I could have missed it.
It was intentional since it would require holding a lock around the search. The
is better SMP performance in the sparsely filled port space (more typical) vs.
better UP performance in the case of a mostly full port space.
> * connect_port_offset() does not (at least from an algorithm point
> of view) need to return an u32, an u16 is sufficient.
If it is truncated to u16, then compiler has to take extra effort to truncate
is unnecessary given later modulo operation.
> Michael Larsen