src/sys/netinet/tcp_hostcache.c, branch release/6.2.0

/* -> /*- for license, minor formatting changes

2005-01-07T01:45:51+00:00

Minor grammer fix in comment.

2004-12-05T22:20:59+00:00

Remove RFC1644 T/TCP support from the TCP side of the network stack.

2004-11-02T22:22:22+00:00

A complete rationale and discussion is given in this message
and the resulting discussion:

 http://docs.freebsd.org/cgi/mid.cgi?4177C8AD.6060706

Note that this commit removes only the functional part of T/TCP
from the tcp_* related functions in the kernel.  Other features
introduced with RFC1644 are left intact (socket layer changes,
sendmsg(2) on connection oriented protocols)  and are meant to
be reused by a simpler and less intrusive reimplemention of the
previous T/TCP functionality.

Discussed on:	-arch

White space cleanup for netinet before branch:

2004-08-16T18:32:07+00:00

- Trailing tab/space cleanup
- Remove spurious spaces between or before tabs

This change avoids touching files that Andre likely has in his working
set for PFIL hooks changes for IPFW/DUMMYNET.

Approved by:	re (scottl)
Submitted by:	Xin LI

Remove the UMA_ZONE_NOFREE flag to all uma_zcreate() calls in the IP and

2004-08-11T17:08:31+00:00

TCP code.  This flag would have prevented giving back excessive free slabs
to the global pool after a transient peak usage.

Correct the displayed bandwidth calculation for a readout via sysctl. The

2004-08-11T10:12:16+00:00

saved value does not have to be scaled with HZ; it is already in bytes per
second.  Only the multiply by eight remains to show bits per second (bps).

Fix a potential race when purging expired hostcache entries.

2004-04-23T13:54:28+00:00

Spotted by:	luigi

Swap destination and source arguments of two bcopy() calls.

2003-12-02T21:25:12+00:00

Before committing the initial tcp_hostcache I changed them from memcpy()
to conform with FreeBSD style without realizing the difference in argument
definition.

This fixes hostcache operation for IPv6 (in general and explicitly IPv6
path mtu discovery) and T/TCP (RFC1644).

Submitted by:	Taku YAMAMOTO 
Approved by:	re (rwatson)

Fix an optimization where I made an ifdef'd out section to broad.

2003-11-28T16:33:03+00:00

When the hostcache bucket limit is reached the last bucket wasn't
removed from the bucket row but inserted a few lines later at the
bucket row head again.  This leads to infinite loop when the same
bucket row is accessed the next time for a lookup/insert or purge
action.

Tested by:	imp, Matt Smith
Approved by:	re (rwatson)

Introduce tcp_hostcache and remove the tcp specific metrics from

2003-11-20T20:07:39+00:00

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.

tcp_hostcache is designed for multiple concurrent access in SMP
environments with high contention and is hash indexed by remote
ip address.

It removes significant locking requirements from the tcp stack with
regard to the routing table.

Reviewed by:	sam (mentor), bms
Reviewed by:	-net, -current, core@kame.net (IPv6 parts)
Approved by:	re (scottl)