freebsd with flexible iflib nic queues
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Archie Cobbs 7734ea0612 Improve performance in the case where ip_output() returns an error.
When this happens, we know for sure that the packet data was not
received by the peer. Therefore, back out any advancing of the
transmit sequence number so that we send the same data the next
time we transmit a packet, avoiding a guaranteed missed packet and
its resulting TCP transmit slowdown.

In most systems ip_output() probably never returns an error, and
so this problem is never seen. However, it is more likely to occur
with device drivers having short output queues (causing ENOBUFS to
be returned when they are full), not to mention low memory situations.

Moreover, because of this problem writers of slow devices were
required to make an unfortunate choice between (a) having a relatively
short output queue (with low latency but low TCP bandwidth because
of this problem) or (b) a long output queue (with high latency and
high TCP bandwidth). In my particular application (ISDN) it took
an output queue equal to ~5 seconds of transmission to avoid ENOBUFS.
A more reasonable output queue of 0.5 seconds resulted in only about
50% TCP throughput. With this patch full throughput was restored in
the latter case.

Reviewed by:	freebsd-net
2000-08-03 23:23:36 +00:00
bin Optimize out no-op chmod() syscalls. 2000-07-29 22:16:55 +00:00
contrib Update for GDB 5.0. 2000-08-02 20:18:50 +00:00
crypto Chalk up another phkmalloc victim. 2000-08-01 08:07:15 +00:00
etc Update rev 1.29 -- 'draft-manning-dsua' is now in its 3rd version. 2000-07-30 19:28:05 +00:00
games Xref strfile(8). 2000-07-31 07:28:16 +00:00
gnu Fix previous commit such that only -S/--skip ignores errors when applying 2000-08-02 22:31:34 +00:00
include Add a prototype for rfork_thread(). 2000-07-29 11:53:35 +00:00
kerberos5 Unbreak heimdal build: we can no longer #include <netinet6/in6.h> 2000-07-06 10:09:59 +00:00
kerberosIV Remove the last vestiges of libRSAglue now that it's an empty stub. 2000-03-11 22:34:10 +00:00
lib Cleanup warnings by adding missint prototypes, removing unneeded duplicate 2000-08-03 09:08:29 +00:00
libexec Honour skey.access(5) by allowing UNIX passwords when skeyaccess(3) 2000-08-01 13:58:55 +00:00
release Fix HTTP port addresses for the IPv6 case. 2000-08-03 02:51:45 +00:00
sbin Resolve conflicts from vendor merge. 2000-08-02 11:38:20 +00:00
secure Install the openssl(1) manpage with an MLINK from ssl(8) to at least put 2000-08-03 05:29:04 +00:00
share Add support for the Netgear GA620T copper gigabit card. 2000-08-02 18:49:17 +00:00
sys Improve performance in the case where ip_output() returns an error. 2000-08-03 23:23:36 +00:00
tools Back out the previous change to the queue(3) interface. 2000-05-26 02:09:24 +00:00
usr.bin Do not display icmp(4) sockets as non-existent bridge(4) sockets. 2000-08-03 14:53:41 +00:00
usr.sbin Change use of perror() to warn() 2000-08-03 23:13:35 +00:00
COPYRIGHT Update to add the July 22, 1999 addendum. 1999-09-05 21:33:47 +00:00
Makefile Mention the buildkernel/installkernel targets in the documentation. 2000-07-31 09:26:59 +00:00
Makefile.inc1 Fix buildkernel and installkernel when KERNEL is defined in 2000-08-03 05:52:22 +00:00
Makefile.upgrade $Id$ -> $FreeBSD$ 1999-08-28 01:35:59 +00:00
README Point out, that build/installkernel need a built world and that more 2000-07-31 12:39:09 +00:00
UPDATING typos from asmodai, one important for device.hints 2000-07-27 20:49:24 +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, the most
commonly used one being ``world'', which rebuilds and installs
everything in the FreeBSD system from the source tree except the
kernel, the kernel-modules and the contents of /etc.  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, documentation
for which can be found at:
   http://www.freebsd.org/handbook/kernelconfig.html
And in the config(8) man page.
Note: If you want to build and install the kernel with the
``buildkernel'' and ``installkernel'' targets, you have to build
world before.  More information is available in the handbook.

The sample kernel configuration files reside in the sys/i386/conf
sub-directory (assuming that you've installed the kernel sources), the
file named GENERIC being the one used to build your initial installation
kernel.  The file NOTES contains entries and documentation for all possible
devices, not just those commonly used.  It is the successor of the ancient
LINT file, but in contrast to LINT, it is not buildable as a kernel but a
pure reference and documentation file.


Source Roadmap:
---------------
bin		System/User commands.

contrib		Packages contributed by 3rd parties.

crypto		Cryptography stuff (see crypto/README).

etc		Template files for /etc

games		Amusements.

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

include		System include files.

kerberosIV	Kerberos package.

lib		System libraries.

libexec		System daemons.

release		Release building Makefile & associated tools.

sbin		System commands.

secure		DES and DES-related utilities - NOT FOR EXPORT!

share		Shared resources.

sys		Kernel sources.

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/handbook/synching.html