代理服务器内核参数优化三则

https://gist.github.com/phuslu/5432976

    $ vi /etc/sysctl.conf
# 系统所有进程一共可以打开的文件数量， 每个套接字也占用一个文件描述字
fs.file-max = 1491124
# 系统同时保持TIME_WAIT套接字的最大数目，http 短链接会产生很多 TIME_WAIT 套接字。
net.ipv4.tcp_max_tw_buckets = 7000
# 关闭 tcp 来源跟踪
net.ipv4.conf.default.accept_source_route = 0
# 缩短套接字处于 TIME_WAIT 的时间， 60s -> 30s
net.ipv4.tcp_fin_timeout = 30
# 启用 TIME_WAIT 复用，使得结束 TIEM_WAIT 状态的套接字的端口可以立刻被其他套接字使用。
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
# 关闭 tcp timestamp, 和 tw_reuse/tw_recycle 同时使用
# tw_recycle 一般不建议使用，RFC1323里面，TCP_TW_RECYCLE和TCP的timestamp选项（timestamp系统默认开启）同时生效的时候，在NAT场景下会导致服务器无法响应连接，这个也是可以复现的。
net.ipv4.tcp_timestamps = 0
# 打开内核的 SYN Cookie 功能，可以防止部分 DOS 攻击。
net.ipv4.tcp_syncookies = 1
# 减小 tcp keepalive 探测次数，可以即时释放长链接
net.ipv4.tcp_keepalive_probes = 3
# 缩短 tcp keepalive 探测间隔时间，同上
net.ipv4.tcp_keepalive_intvl = 15
# 增大内核 backlog 参数，使得系统能够保持更多的尚未完成 TCP 三次握手的套接字。
net.ipv4.tcp_max_syn_backlog = 8388608
# 同上
net.core.netdev_max_backlog = 8388608
# 同上
net.core.somaxconn = 8388608
# 默认参数
net.ipv4.tcp_keepalive_time = 7200
# 关闭对更大的滑动窗口(如长肥管道)支持，节省系统计算资源
net.ipv4.tcp_window_scaling = 0
# 关闭内核对误码大约拥塞的环境(如wifi/3g)的TCP优化，有线线路不需要 tcp_sack
net.ipv4.tcp_sack = 0
# 增大应用程序可用端口范围。
net.ipv4.ip_local_port_range = 1024 65000
# Increase TCP buffer sizes
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216
net.ipv4.tcp_congestion_control = cubic
 
 
$vi /etc/security/limits.conf
# 增大应用程序的最大打开文件数目限制
* hard    nofile          65535
* soft    nofile          65535
 
$ vi /etc/nginx/nginx.conf
# This number should be, at maximum, the number of CPU cores on your system. 
worker_processes 8;
 
# Number of file descriptors used for Nginx. This is set in the OS with 'ulimit -n 200000'
# or using /etc/security/limits.conf
worker_rlimit_nofile 200000;
 
# only log critical errors
error_log /var/log/nginx/error.log crit
 
# Determines how many clients will be served by each worker process.
# (Max clients = worker_connections * worker_processes)
# "Max clients" is also limited by the number of socket connections available on the system (~64k)
worker_connections 4000;
 
# essential for linux, optmized to serve many clients with each thread
use epoll;
 
# Accept as many connections as possible, after nginx gets notification about a new connection.
# May flood worker_connections, if that option is set too low.
multi_accept on;
 
# Caches information about open FDs, freqently accessed files.
# Changing this setting, in my environment, brought performance up from 560k req/sec, to 904k req/sec.
# I recommend using some varient of these options, though not the specific values listed below.
open_file_cache max=200000 inactive=20s; 
open_file_cache_valid 30s; 
open_file_cache_min_uses 2;
open_file_cache_errors on;
 
# Buffer log writes to speed up IO, or disable them altogether
#access_log /var/log/nginx/access.log main buffer=16k;
access_log off;
 
# Sendfile copies data between one FD and other from within the kernel. 
# More efficient than read() + write(), since the requires transferring data to and from the user space.
sendfile on; 
 
# Tcp_nopush causes nginx to attempt to send its HTTP response head in one packet, 
# instead of using partial frames. This is useful for prepending headers before calling sendfile, 
# or for throughput optimization.
tcp_nopush on;
 
# don't buffer data-sends (disable Nagle algorithm). Good for sending frequent small bursts of data in real time.
tcp_nodelay on; 
 
# Timeout for keep-alive connections. Server will close connections after this time.
keepalive_timeout 30;
 
# Number of requests a client can make over the keep-alive connection. This is set high for testing.
keepalive_requests 100000;
 
# allow the server to close the connection after a client stops responding. Frees up socket-associated memory.
reset_timedout_connection on;
 
# send the client a "request timed out" if the body is not loaded by this time. Default 60.
client_body_timeout 10;
 
# If the client stops reading data, free up the stale client connection after this much time. Default 60.
send_timeout 2;
 
# Compression. Reduces the amount of data that needs to be transferred over the network
gzip on;
gzip_min_length 10240;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/xml;
gzip_disable "MSIE [1-6]\.";

http://hong.im/2013/04/20/linux-tcp-tuning/

    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 攻击，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
# 修改系統默认的 TIMEOUT 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 = 10000 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 10000 到 65000。（注意：这里不要将最低值设的太低，否则可能会占用掉正常的端口！）
net.ipv4.tcp_max_syn_backlog = 8192
# 表示 SYN 队列的长度，默认为 1024，加大队列长度为 8192，可以容纳更多等待连接的网络连接数。
net.ipv4.tcp_max_tw_buckets = 5000
# 表示系统同时保持 TIME_WAIT 的最大数量，如果超过这个数字，TIME_WAIT 将立刻被清除并打印警告信息。
# increase TCP max buffer size settable using setsockopt()
net.core.rmem_max = 67108864 
net.core.wmem_max = 67108864 
# increase Linux autotuning TCP buffer limit
net.ipv4.tcp_rmem = 4096 87380 67108864
net.ipv4.tcp_wmem = 4096 65536 67108864
# increase the length of the processor input queue
net.core.netdev_max_backlog = 250000
# recommended for hosts with jumbo frames enabled
net.ipv4.tcp_mtu_probing=1

https://gist.github.com/madeye/8146912

    net.core.wmem_max = 12582912
net.core.rmem_max = 12582912
net.ipv4.tcp_rmem = 10240 87380 12582912
net.ipv4.tcp_wmem = 10240 87380 12582912
net.ipv4.ip_local_port_range = 18000    65535
net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_max_syn_backlog = 3240000
net.core.somaxconn = 3240000
net.ipv4.tcp_max_tw_buckets = 1440000
net.ipv4.tcp_congestion_control = cubic
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_tw_recycle = 1