cvs commit: src/sys/conf files src/sys/net if_faith.c if_loop.c route.h rtsock.c src/sys/netinet in_pcb.c in_pcb.h in_rmx.c ip_divert.c ip_fw2.c ip_icmp.c ip_input.c ip_output.c

[Nate Lawson]

On Thu, 20 Nov 2003, Andre Oppermann wrote:
>   Modified files:
>     sys/conf             files
>     sys/net              if_faith.c if_loop.c route.h rtsock.c
>     sys/netinet          in_pcb.c in_pcb.h in_rmx.c ip_divert.c
>                          ip_fw2.c ip_icmp.c ip_input.c ip_output.c
>                          raw_ip.c tcp_input.c tcp_output.c
>                          tcp_subr.c tcp_syncache.c tcp_timer.c
>                          tcp_usrreq.c tcp_var.h udp_usrreq.c
>     sys/netinet6         icmp6.c in6_pcb.c in6_rmx.c in6_src.c
>                          ip6_output.c udp6_output.c
>   Added files:
>     sys/netinet          tcp_hostcache.c
>   Log:
>   Introduce tcp_hostcache and remove the tcp specific metrics from
>   the routing table.  Move all usage and references in the tcp stack
>   from the routing table metrics to the tcp hostcache.
>
>   It caches measured parameters of past tcp sessions to provide better
>   initial start values for following connections from or to the same
>   source or destination.  Depending on the network parameters to/from
>   the remote host this can lead to significant speedups for new tcp
>   connections after the first one because they inherit and shortcut
>   the learning curve.

This is very good.  There was no reason to throw away rtt estimates each
time a connection closed.  Especially for http servers, this should make a
big difference.  Thanks so much!

One great paper I read on this:
Prashant Pradhan, Tzi-Cker Chiueh, Anindya Neogi, Aggregate TCP Congestion
Control Using Multiple Network Probing, in proceedings of IEEE ICDCS'2000.
http://www.ecsl.cs.sunysb.edu/~prashant/papers/atcp.ps.gz

-Nate