out of socket memory调整

主要是调整TCP缓冲区

Increasing the TCP send and receive buffers will increase the performance a lot if (and only if) you have a lot of large files to send.

增加TCP 发送和接收缓冲区对性能有很大的提高，在你有大文件发送的情况下

net.ipv4.tcp_wmem = 4096 65536 524288

net.core.wmem_max = 1048576

If you have a lot of large file uploads, increasing the receive buffers will help.

如果你有大文件上传，增大接收缓冲区对给你带来帮助

net.ipv4.tcp_rmem = 4096 87380 524288

net.core.rmem_max = 1048576

# These ensure that TIME_WAIT ports either get reused or closed fast.

以下参数确保TIME_WAIT 快速关闭

net.ipv4.tcp_fin_timeout = 1   ##打开fin_wait 快速关闭参数

net.ipv4.tcp_tw_recycle = 1    ##快速回收fin_wait参数

设置内核TCP的相关参数

# TCP memory

net.core.rmem_max = 16777216    ##内核最大接收缓冲 16M

net.core.rmem_default = 16777216  ##内核黙认接收缓冲 16M

net.core.netdev_max_backlog = 262144   ##2M

net.core.somaxconn = 262144    ##2M

net.ipv4.tcp_syncookies = 1      ##打开SYN_COOKIE

net.ipv4.tcp_max_orphans = 262144 ##2M

net.ipv4.tcp_max_syn_backlog = 262144 ##SYN 队列大小 2M

net.ipv4.tcp_synack_retries = 2 ##SYN_ACK重试时间 2秒

net.ipv4.tcp_syn_retries = 2   ## SYN 重试时间   2秒

# you shouldn't be using conntrack on a heavily loaded server anyway, but these are

# suitably high for our uses, insuring that if conntrack gets turned on, the box doesn’t die

如果用到IPTABLES 同样在增长ip_conntrack 的大小，这个是iptables 所管理的状态数目

net.ipv4.ip_conntrack_max = 1048576

net.ipv4.netfilter.ip_conntrack_max = 1048576

原文：

http://hi.baidu.com/lewutian/item/b7fe3cc56f966345a8ba94c2