TCP/networking tunning

Kernel TCP Networking tunning .
You can achieve a high network performance by adjusting some value to to the kernel
From http://www.gentoo-wiki.info/HOWTO_TCP_Tuning
http://blogs.techrepublic.com.com/opensource/?p=62
http://www.freebsd.org/doc/en/books/handbook/index.html

Variables to Change, and suggested Values

net.core.rmem_max="16777216"

This setting changes the maximum network receive buffer size to 16777216 bytes.

net.core.wmem_max="16777216"

The same thing for the send buffer

net.ipv4.tcp_rmem="4096 87380 16777216"

This sets the kernel's minimum, default, and maximum TCP receive buffer sizes. You might be surprised, seeing the maximum of 16M, that many Unix-like operating systems still have a maximum of 256K!

net.ipv4.tcp_wmem="4096 65536 16777216"

A similar setting for the TCP send buffer. Note that the default value is a little lower. Don't worry about this, the send buffer size is less important than the receive buffer.

net.ipv4.tcp_no_metrics_save=1

Moreover, There are a couple of kernel value you should adjust
tcp_max_syn_backlog
somaxconn