在服务器安装了LNMP(Linux+Nginx+Mysql+php)环境之后Linux服务器参数必须做必要的优化,包括网络参数优化、文件数优化、内存优化等等。

1、网络参数优化:

这部分主要参照张宴大师 《Nginx 0.8.x + PHP 5.2.13(FastCGI)搭建胜过Apache十倍的Web服务器(第6版)[原创]》其中 五、优化Linux内核参数的内容:

vi /etc/sysctl.conf #编辑sysctl.conf文件
#在/etc/sysctl.conf中添加如下内容
# 网络参数优化开始
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
#网络参数优化结束
#添加内容结束


修改完成后运行以下命令使参数生效:
/sbin/sysctl -p


2、系统最大打开文件数优化
默认情况下,系统允许最大打开文件数为1024个,这对于访问量较大的web服务器来说远远不够用。系统最大打开文件数可以通过ulimit来修改和查询。
一般情况下,可以通过ulimit -n来查看目前系统允许的最大打开文件数,例如 :
ulimit -n 
1024 #系统返回


如果我们要修改系统允许最大文件打开数,可以通过ulimit -SHn来做,例如要临时修改系统最大打开文件数为51201个,那么用如下命令:
ulimit -SHn 51201

每次重启系统时,该值会被自动还原,可以将上述命令写入 /etc/rc.local 中。如果想永久更改,可以按照如下修改:
vi /etc/security/limits.conf  
# add
* soft nofile 51201
* hard nofile 51201


系统最大打开文件数影响到的配置文件(以下必须设置为系统设置相一致,例如设置系统最大打开文件数为:51201):
A、Nginx配置文件nginx.conf的配置项:worker_rlimit_nofile、worker_connections、open_file_cache等,例如设置为:
  worker_rlimit_nofile 51201;
  events 
  {
    use epoll;
    worker_connections 51201;
  }
  http 
  {
    #其它参数略过
    open_file_cache max=51201 inactive=20s;  
    open_file_cache_min_uses 1;  
    open_file_cache_valid 30s;
    #其它参数略过
  }
B、FastCGI配置文件php-fpm.conf的配置项
   51201

3、系统共享内存优化:

系统共享内存大小主要影响到eaccelerator的设置:
eaccelerator.shm_size="32"

该项为eaccelerator可使用的共享内存大小(单位为MB)设置。
在Linux下,单个进程的最大共享内存使用量受/proc/sys/kernel/shmmax中设置的数字限制(单位为字节),例如Redhat 4.7的shmmax默认值为33554432字节(33554432bytes/1024/1024=32MB)。
临时更改该值(例如修改为128MB=128x1024x1024=134217728字节):

echo 134217728 > /proc/sys/kernel/shmmax
echo 134217728 > /proc/sys/kernel/shmall

按照以上方法更改,在每次重启系统时,该值会被自动还原。如果想永久更改,可以修改/etc/sysctl.conf文件,设置:
#系统共享内存大小优化
kernel.shmmax = 134217728

完整的/etc/sysctl.conf修改添加内容如下:
#在/etc/sysctl.conf中添加如下内容
# 网络参数优化开始
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
#网络参数优化结束
#系统共享内存大小优化开始
kernel.shmmax = 134217728
#系统共享内存大小优化结束
#添加内容结束

修改完成后运行以下命令使参数生效
/sbin/sysctl -p
以上,如有不足,欢迎大家指正和追加,谢谢!

 

 

 

 

 

 

 

高负载linux服务器的内核调优
vi /etc/sysctl.conf,修改内核参数:
kernel.shmall = 268435456
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.ip_local_port_range = 1024 65000
net.ipv4.tcp_max_tw_buckets = 5000
net.ipv4.tcp_max_tw_buckets = 5000
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.ip_local_port_range = 5000 65000
net.ipv4.tcp_mem = 786432 1048576 1572864
net.core.wmem_max = 873200
net.core.rmem_max = 873200
net.ipv4.tcp_wmem = 8192 436600 873200
net.ipv4.tcp_rmem = 32768 436600 873200
net.core.somaxconn = 256
net.core.netdev_max_backlog = 1000
net.ipv4.tcp_max_syn_backlog = 2048
net.ipv4.tcp_retries2 = 5
net.ipv4.tcp_keepalive_time = 500
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.conf.lo.arp_ignore = 0
net.ipv4.conf.lo.arp_announce = 0
net.ipv4.conf.all.arp_ignore = 0
net.ipv4.conf.all.arp_announce = 0

几个解释:
net.ipv4.tcp_syncookies = 1
#表示开启SYN Cookies。当出现SYN等待队列溢出时,启用cookies来处理,可防范少量SYN***,默认为0,表示关闭;
net.ipv4.tcp_tw_reuse = 1
#表示开启重用。允许将TIME-WAIT sockets重新用于新的TCP连接,默认为0,表示关闭;
net.ipv4.tcp_tw_recycle = 1
#表示开启TCP连接中TIME-WAIT sockets的快速回收,默认为0,表示关闭。
net.ipv4.tcp_fin_timeout = 30
#表示如果套接字由本端要求关闭,这个参数决定了它保持在FIN-WAIT-2状态的时间。
net.ipv4.tcp_keepalive_time = 1200 
#表示当keepalive起用的时候,TCP发送keepalive消息的频度。缺省是2小时,改为20分钟。
net.ipv4.ip_local_port_range = 1024    65000 
#表示用于向外连接的端口范围。缺省情况下很小:32768到61000,改为1024到65000。
net.ipv4.tcp_max_tw_buckets = 5000
#表示系统同时保持TIME_WAIT套接字的最大数量,如果超过这个数字,
#TIME_WAIT套接字将立刻被清除并打印警告信息。默认为180000,改为5000。
#对于Apache、Nginx等服务器,上几行的参数可以很好地减少TIME_WAIT套接字数量,
#但是对于Squid,效果却不大。此项参数可以控制TIME_WAIT套接字的最大数量,避免Squid服务器被大量的TIME_WAIT套接字拖死

 

完整的内核优化配置:

net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 262144
net.core.somaxconn = 262144
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 1
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
net.ipv4.tcp_keepalive_time = 30
net.ipv4.ip_local_port_range = 1024 65000

 

~]# sysctl -p 
net.ipv4.ip_forward = 0 
net.ipv4.conf.default.rp_filter = 1 
net.ipv4.conf.default.accept_source_route = 0 
kernel.sysrq = 0 
kernel.core_uses_pid = 1 
net.ipv4.tcp_syncookies = 1 
kernel.msgmnb = 65536 
kernel.msgmax = 65536 
kernel.shmmax = 4294967295 
kernel.shmall = 268435456 
kernel.sem = 250        32000   100     128 
fs.file-max = 65535 
net.ipv4.ip_local_port_range = 1024     65535 
net.core.wmem_max = 262144 
net.core.wmem_default = 262144 
net.core.rmem_default = 262144 
net.core.rmem_max = 262144

 

修改/etc/sysctl.conf, /sbin/sysctl -p立即生效
永久修改内核参数: echo “10″ > /proc/sys/net/ipv4/tcp_fin_timeout

各种参数的意思:http://ipsysctl-tutorial.frozentux.net/ipsysctl-tutorial.html
还参考了:http://trac.lighttpd.net/trac/wiki/Docs%3APerformance#platform-specific-notes

net.ipv4.tcp_fin_timeout = 10
net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
#tcp port range
net.ipv4.ip_local_port_range = 4096 65000
#tcp send buffer. min, default , and max
net.ipv4.tcp_wmem = 4096 65536 16777216
#tcp reservie buffer.
#net.ipv4.tcp_rmem = 4096 65536 16777216