Re: [lwip-devel] more about SO_REUSE and UDP

[Leon Woestenberg]

Hello Luke,

Luke wrote:
> On Thu, 25 Mar 2004, Leon Woestenberg wrote:
>
> > For optimal lookup behaviour (on heavy traffic networks) the alternative
> > is to have dummy PCB's in the UDP/TCP list, that have a new PCB_DROP
> > flag set.
> >
> > This way, the PCB's *can* be sorted by most-targetted destination port
> > to least-targetted port, dynamically with reference count and the
> > overall lookup time is reduced to a minimum. Increased overhead due to
> > sorting though.
>
>
> We found that traversing the PCB list was extremely expensive when we had
> a system with lots of simultaneous connections. I fixed it by first
>
In the order of how many connections are we talking? tens, thousands?

> abstracting pcb lists into a separate, well defined interface, and then
> implemented a hashtable to do fast PCB lookups. This approach would work
> well for UDP as well, and is in my opinion a more thorough solution to the
> linear searches currently used for handling PCB lists.
How would your hash implementation handle the case where 95% of the 
inbound (broadcast) traffic is on unlistened ports?

What would the overhead be if lwIP has say, typically five connections open?

Regards,

Leon.