Route caching ?

[Bruce M. Simpson]

Ivo Vachkov wrote:
> Actually there is:
>
> struct	route_in6 ip6_forward_rt;
>
> that "caches" the last route used (thanks blue !!!) but i think this
> technique is pointless in a multiflow traffic.
>   

Yes, this is why OpenBSD got rid of this form of 'route caching'.

> Is it reasonable to believe that route caches can improve networking
> performance or we should leave it up to the routing table itself ?
>   

I believe that if one goes beyond a single radix trie, as is needed for 
multi-pathing with multicast and source policy routing, route caching is 
*required* to achieve good performance.

Also, if FreeBSD moves ARP and NDP out of the radix trie, a route cache 
would be highly preferable as it amortizes the lock acquisition which 
would other be required for ARP/NDP/other layer 2 next-hop resolution.

BMS