ubuntu 优化

1.修改最大文件句柄数

  ubuntu 修改方法：

    vi /etc/profile

   添加 ulimit -SHn 65536

   退出  source  /etc/profile

这样不是对所有用户有效 还要修改 /etc/security/limits.conf

注意：centos修改方法  

     vi /etc/security/limits.conf

文件尾追加 
* hard nofile 40960
* soft nofile 40960

网络参数调整

net.ipv4.tcp_max_syn_backlog = 65536
net.core.netdev_max_backlog =  32768
net.core.somaxconn = 32768

net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216

net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 2

net.ipv4.tcp_tw_recycle = 1
#net.ipv4.tcp_tw_len = 1
net.ipv4.tcp_tw_reuse = 1

net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_max_orphans = 3276800

#net.ipv4.tcp_fin_timeout = 30
#net.ipv4.tcp_keepalive_time = 120
net.ipv4.ip_local_port_range = 1024  65535