View source for TCP

* http://articles.techrepublic.com.com/5100-10878_11-1050878.html -- "TCP/IP options for high-performance data transmission"
* http://www.ussg.iu.edu/hypermail/linux/kernel/0102.0/0943.html -- [[LKML]] thread, "TCP_NOPUSH on FreeBSD, TCP_CORK on Linux"
* http://www.irbs.net/internet/postfix/0707/1097.html -- postfix thread, "dkim-milter signing terribly slow with Postfix, but not with sendmail"
** This becomes: "TCP_NODELAY, TCP_CORK, TCP_NOPUSH, etc (was: dkim-milter signing terribly slow...)"

== Portable APIs ==
* TCP_NODELAY: Disable [[Nagle's algorithm]] (coalescing of small packets until an ACK is received or a retransmission triggered). See the [[Linux APIs#IPPROTO_TCP|Linux APIs]] page for interactions with TCP_CORK on that platform.
==Offloading/Coalescing==
LRO/TSO are safe to use on routers and bridges so long as all interfaces involved support the technique.
===LRO===
Large receive offload. Cannot guarantee refragmentation, and thus ought not generally be used on bridges or routers.
===GRO===
Generic receive offload. Generalizes LRO to guarantee possibility of refragmentation, but coalesces a proper subset of packets suitable for LRO.
===TSO===
TCP segmentation offload, also known as TCP Large Send.
===GSO===
Generic segmentation offload, introduced in Linux 2.6.18. Generalizes TSO to guarantee possibility of refragmentation.
==Tuning==
===TCP auto-tuning on Linux===
* netdev 2009-03-11, "[http://patchwork.ozlabs.org/patch/24296/ TCP rx window autotuning harmful at LAN context]"
* The Pittsburgh Supercomputing Center's [http://www.psc.edu/networking/projects/tcptune/#Linux Linux TCP notes]
===TCP auto-tuning on FreeBSD===
* Finally introduced in [FreeBSD 7.2] by [http://people.freebsd.org/~andre/ Andre Oppermann]:
<pre>With TCP send buffer auto scaling and the default values below it supports 20Mbit/s at 100ms and 10Mbit/s at 200ms. Both read and write buffer are auto-sized.</pre>
== See also ==
* [[Linux APIs#IPPROTO_TCP|Linux's]] TCP socket options
* [[FreeBSD APIs#IPPROTO_TCP|FreeBSD's]] TCP socket options
* [http://linuxgazette.net/135/pfeiffer.html TCP and Linux' Pluggable Congestion Control Algorithms], a 2007 Linux Gazette article by René Pfeiffer
* [http://thread.gmane.org/gmane.linux.network/114003 'net: Generic Receive Offload], Herbert Xu 2008-12-12 linux-net post
* [http://www.linuxfoundation.org/collaborate/workgroups/networking/gso GSO], The Linux Foundation
* [http://kerneltrap.org/node/397 Linux: TCP Segmentation Offload], KernelTrap 2002-09-03
[[CATEGORY: Networking]]