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gallatin 11f6fcfd28 Rework IPV6 TCP path MTU discovery to match IPv4
- Re-write tcp_ctlinput6() to closely mimic the IPv4 tcp_ctlinput()

- Now that tcp_ctlinput6() updates t_maxseg, we can allow ip6_output()
  to send TCP packets without looking at the tcp host cache for every
  single transmit.

- Make the icmp6 code mimic the IPv4 code & avoid returning
  PRC_HOSTDEAD because it is so expensive.

Without these changes in place, every TCP6 pmtu discovery or host
unreachable ICMP resulted in a call to in6_pcbnotify() which walks the
tcbinfo table with the write lock held.  Because the tcbinfo table is
shared between IPv4 and IPv6, this causes huge scalabilty issues on
servers with lots of (~100K) TCP connections, to the point where even
a small percent of IPv6 traffic had a disproportionate impact on
overall throughput.

Reviewed by:	bz, rrs, ae (all earlier versions), lstewart (in Netflix's tree)
Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D7272
2016-08-01 17:02:21 +00:00
bin sh: Fix a clang warning. 2016-07-31 13:11:34 +00:00
cddl Cast result from third parameter to int instead of promoting it to size_t 2016-07-31 06:03:27 +00:00
contrib Remove usage of _WITH_DPRINTF 2016-07-30 01:16:06 +00:00
crypto Remove duplicate symbols from libroken version-script.map 2016-07-21 18:12:39 +00:00
etc Move chown tests to proper path 2016-07-23 05:49:18 +00:00
gnu rename ARM's libunwind.S to to avoid conflict with llvm libunwind 2016-07-27 16:34:19 +00:00
include Fix up setgrent(3) to have a POSIX-compliant prototype. 2016-07-31 08:05:15 +00:00
kerberos5 DIRDEPS_BUILD: Update dependencies 2016-06-14 16:55:05 +00:00
lib Fix up setgrent(3) to have a POSIX-compliant prototype. 2016-07-31 08:05:15 +00:00
libexec Fix dlsym(RTLD_NEXT) handling to only return the next library in last library cases. 2016-07-15 19:07:00 +00:00
release Create a /usr/home -> /home symlink for the arm images to 2016-07-20 22:49:33 +00:00
rescue DIRDEPS_BUILD: Fix and hookup rescue/rescue to the build. 2016-05-26 23:20:40 +00:00
sbin An old tables implementation had all tables preallocated, 2016-08-01 13:38:48 +00:00
secure Revert r301551, which added blacklistd(8) to sshd(8). 2016-06-24 23:22:42 +00:00
share Man page for the new checksum netgraph module. 2016-08-01 12:14:21 +00:00
sys Rework IPV6 TCP path MTU discovery to match IPv4 2016-08-01 17:02:21 +00:00
targets Add clang-format under WITH_CLANG_EXTRAS. 2016-06-17 16:46:58 +00:00
tests Fix locking issues with aio_fsync(). 2016-07-29 18:26:15 +00:00
tools Remove calls to die added for associated bugs 2016-07-31 06:28:40 +00:00
usr.bin indent(1): Use a dash in the license headers. 2016-08-01 16:40:42 +00:00
usr.sbin Fix up setgrent(3) to have a POSIX-compliant prototype. 2016-07-31 08:05:15 +00:00
.arcconfig Remove project.name which is a product of a bygone era. 2016-04-21 04:33:07 +00:00
.arclint phabricator related changes: 2015-04-20 20:33:22 +00:00
COPYRIGHT Bump copyright year. 2015-12-31 11:21:45 +00:00
LOCKS
MAINTAINERS Remove myself from kern_timeout.c yeah! 2016-07-27 20:37:32 +00:00
Makefile SYSTEM_COMPILER: Rework the logic to allow a 'make test-system-compiler'. 2016-07-24 18:05:05 +00:00
Makefile.inc1 Add libprocstat prebuild library dependencies. 2016-07-30 03:43:55 +00:00
Makefile.libcompat Don't disable binutils/elftoolchain bootstrapping with external compiler. 2016-07-24 18:50:11 +00:00
ObsoleteFiles.inc Add tblgen to ObsoleteFiles.inc, as it was renamed to llvm-tblgen. 2016-07-28 18:40:43 +00:00
README README: remove nonexistent 'games' directory. 2016-05-18 10:43:13 +00:00
UPDATING Minor wording improvements to the note about pipe(2) removal. 2016-07-20 18:00:22 +00:00

This is the top level of the FreeBSD source directory.  This file
was last revised on:
$FreeBSD$

For copyright information, please see the file COPYRIGHT in this
directory (additional copyright information also exists for some
sources in this tree - please see the specific source directories for
more information).

The Makefile in this directory supports a number of targets for
building components (or all) of the FreeBSD source tree.  See build(7)
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html
for more information, including setting make(1) variables.

The `buildkernel` and `installkernel` targets build and install
the kernel and the modules (see below).  Please see the top of
the Makefile in this directory for more information on the
standard build targets and compile-time flags.

Building a kernel is a somewhat more involved process.  See build(7), config(8),
and http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html
for more information.

Note: If you want to build and install the kernel with the
`buildkernel` and `installkernel` targets, you might need to build
world before.  More information is available in the handbook.

The kernel configuration files reside in the sys/<arch>/conf
sub-directory.  GENERIC is the default configuration used in release builds.
NOTES contains entries and documentation for all possible
devices, not just those commonly used.


Source Roadmap:
---------------

bin		System/user commands.

cddl		Various commands and libraries under the Common Development
		and Distribution License.

contrib		Packages contributed by 3rd parties.

crypto		Cryptography stuff (see crypto/README).

etc		Template files for /etc.

gnu		Various commands and libraries under the GNU Public License.
		Please see gnu/COPYING* for more information.

include		System include files.

kerberos5	Kerberos5 (Heimdal) package.

lib		System libraries.

libexec		System daemons.

release		Release building Makefile & associated tools.

rescue		Build system for statically linked /rescue utilities.

sbin		System commands.

secure		Cryptographic libraries and commands.

share		Shared resources.

sys		Kernel sources.

tests		Regression tests which can be run by Kyua.  See tests/README
		for additional information.

tools		Utilities for regression testing and miscellaneous tasks.

usr.bin		User commands.

usr.sbin	System administration commands.


For information on synchronizing your source tree with one or more of
the FreeBSD Project's development branches, please see:

  http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html