Linux系统优化部分内核参数调优中文注释

应用服务器sysctl.conf部分参数
## network configurations
net.ipv4.ip_forward = 0 # IP packet forwarding
net.ipv4.tcp_tw_reuse=1
net.ipv4.tcp_tw_recycle=1
net.ipv4.tcp_fin_timeout=30  #60,每条至多占 1.5K 的内存
net.ipv4.tcp_keepalive_time=1800 #7200
net.core.netdev_max_backlog=3000 #1000每个网络接口接收数据包的速率比内核处理这些包的速率快时,允许送到队列的数据包的最大数目
net.ipv4.tcp_max_syn_backlog=4096  #1024 增加TCP SYN队列长度,使系统可以处理更多的并发连接
net.core.wmem_default = 2097152 #108544,系统套接字缓冲区
net.core.rmem_default = 2097152 #108544,系统套接字缓冲区
net.core.rmem_max=16777216   #131071,系统套接字缓冲区
net.core.wmem_max=16777216 #131071,系统套接字缓冲区
net.ipv4.tcp_rmem=4096 87380 16777216  #4096   87380   174760, TCP接收缓冲区
net.ipv4.tcp_wmem=4096 65536 16777216 #4096  16384   131072, TCP发送缓冲区
net.ipv4.tcp_mem = 786432 1048576 1572864 # Out of socket memory
net.ipv4.tcp_syncookies=1  #0,防SyncFlood攻击
net.ipv4.ip_local_port_range = 32768 61000 #用于向外连接的端口范围,这是默认值
net.ipv4.tcp_max_tw_buckets = 5000  #180000,同时保持TIME_WAIT套接字的最大数量
#以下可能需要加载ip_conntrack模块 modprobe ip_conntrack
# net.ipv4.ip_conntrack_max=6553600
# net.ipv4.netfilter.ip_conntrack_tcp_timeout_established = 1800
# net.ipv4.netfilter.ip_conntrack_max=6553600
# net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait=120
# net.ipv4.netfilter.ip_conntrack_tcp_timeout_close_wait=60
# net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait=120
# net.ipv4.icmp_echo_ignore_all = 1 #0, Disable ping requests
# net.ipv4.icmp_echo_ignore_broadcasts = 1 #1, Enable ignoring broadcasts request
net.ipv4.neigh.default.gc_thresh3 = 40960 #1024
net.ipv4.neigh.default.gc_thresh2 = 20480 #512
net.ipv4.neigh.default.gc_thresh1 = 10240 #128
##以上三条语句可以解决内核中出现的如下两行错误
#Linux kernel: printk: xxxxx messages suppressed.
#Linux kernel: Neighbour table overflow.

## system configurations
fs.file-max = 372901 #23712, 整个系统所有可打开文件总数的限制, 可按256/4M内存计算值。
# ulimit -n 10000 #某一程序可打开文件 总数的限制
# kernel.ctrl-alt-del = 1 #0,Disable CTR+ALT+DEL Restart Keys

附:sysctl.conf
fs.file-max = 372901
net.ipv4.tcp_tw_reuse=1
net.ipv4.tcp_tw_recycle=1
net.ipv4.tcp_fin_timeout=30
net.ipv4.tcp_keepalive_time=1800
net.core.netdev_max_backlog=3000
net.ipv4.tcp_max_syn_backlog=4096
net.core.wmem_default = 2097152
net.core.rmem_default = 2097152
net.ipv4.tcp_rmem=4096 87380 16777216
net.core.rmem_max=33554432
net.ipv4.tcp_wmem=4096 65536 16777216
net.core.wmem_max=33554432
net.ipv4.tcp_mem = 786432 1048576 1572864
net.ipv4.tcp_syncookies=1
net.ipv4.tcp_max_tw_buckets = 180000
net.ipv4.ip_conntrack_max=6553600
net.ipv4.netfilter.ip_conntrack_max=6553600
net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait=60
net.ipv4.netfilter.ip_conntrack_tcp_timeout_close_wait=30
net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait=60
net.ipv4.ip_local_port_range = 32768 61000

注意:这个配置似乎有问题:在centos6.2上使用,用apache跑web,第一次打开页面正常,但再打开另一个页面就打不开了,有时会“连接已重置”,要过几分钟才恢复正常。具体问题出在哪里目前还不清楚。

因此该配置请慎用!




coded by nessus
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