如何设置Sysctl.conf用以提高Linux的性能(最完整的）

 　　Sysctl是一个允许您改变正在运行中的Linux系统的接口。它包含一些 TCP/IP 堆栈和虚拟内存系统的高级选项， 这可以让有经验的管理员提高引人注目的系统性能。用sysctl可以读取设置超过五百个系统变量。基于这点，sysctl(8) 提供两个功能：读取和修改系统设置。,　　查看所有可读变量：,　　% sysctl -a,　　读一个指定的变量，例如 kern.maxproc：,　　% sysctl kern.maxproc kern.maxproc: 1044,　　要设置一个指定的变量，直接用 variable=value 这样的语法：,　　# sysctl kern.maxfiles=5000,　　kern.maxfiles: 2088 -> 5000,　　您可以使用sysctl修改系统变量，也可以通过编辑sysctl.conf文件来修改系统变量。sysctl.conf 看起来很像 rc.conf。它用 variable=value 的形式来设定值。指定的值在系统进入多用户模式之后被设定。并不是所有的变量都可以在这个模式下设定。,　　sysctl 变量的设置通常是字符串、数字或者布尔型。 (布尔型用 1 来表示’yes’，用 0 来表示’no’)。,　　sysctl -w kernel.sysrq=0,　　sysctl -w kernel.core_uses_pid=1,　　sysctl -w net.ipv4.conf.default.accept_redirects=0,　　sysctl -w net.ipv4.conf.default.accept_source_route=0,　　sysctl -w net.ipv4.conf.default.rp_filter=1,　　sysctl -w net.ipv4.tcp_syncookies=1,　　sysctl -w net.ipv4.tcp_max_syn_backlog=2048,　　sysctl -w net.ipv4.tcp_fin_timeout=30,　　sysctl -w net.ipv4.tcp_synack_retries=2,　　sysctl -w net.ipv4.tcp_keepalive_time=3600,　　sysctl -w net.ipv4.tcp_window_scaling=1,　　sysctl -w net.ipv4.tcp_sack=1,　　配置sysctl,　　编辑此文件：,　　vi /etc/sysctl.conf,　　如果该文件为空，则输入以下内容，否则请根据情况自己做调整：,　　# Controls source route verification,　　# Default should work for all interfaces,　　net.ipv4.conf.default.rp_filter = 1,　　# net.ipv4.conf.all.rp_filter = 1,　　# net.ipv4.conf.lo.rp_filter = 1,　　# net.ipv4.conf.eth0.rp_filter = 1,　　# Disables IP source routing,　　# Default should work for all interfaces,　　net.ipv4.conf.default.accept_source_route = 0,　　# net.ipv4.conf.all.accept_source_route = 0,　　# net.ipv4.conf.lo.accept_source_route = 0,　　# net.ipv4.conf.eth0.accept_source_route = 0,　　# Controls the System Request debugging functionality of the kernel,　　kernel.sysrq = 0,　　# Controls whether core dumps will append the PID to the core filename.,　　# Useful for debugging multi-threaded applications.,　　kernel.core_uses_pid = 1,　　# Increase maximum amount of memory allocated to shm,　　# Only uncomment if needed!,　　# kernel.shmmax = 67108864,　　# Disable ICMP Redirect Acceptance,　　# Default should work for all interfaces,　　net.ipv4.conf.default.accept_redirects = 0,　　# net.ipv4.conf.all.accept_redirects = 0,　　# net.ipv4.conf.lo.accept_redirects = 0,　　# net.ipv4.conf.eth0.accept_redirects = 0,　　# Enable Log Spoofed Packets, Source Routed Packets, Redirect Packets,　　# Default should work for all interfaces,　　net.ipv4.conf.default.log_martians = 1,　　# net.ipv4.conf.all.log_martians = 1,　　# net.ipv4.conf.lo.log_martians = 1,　　# net.ipv4.conf.eth0.log_martians = 1,　　# Decrease the time default value for tcp_fin_timeout connection,　　net.ipv4.tcp_fin_timeout = 25,　　# Decrease the time default value for tcp_keepalive_time connection,　　net.ipv4.tcp_keepalive_time = 1200,　　# Turn on the tcp_window_scaling,　　net.ipv4.tcp_window_scaling = 1,　　# Turn on the tcp_sack,　　net.ipv4.tcp_sack = 1,　　# tcp_fack should be on because of sack,　　net.ipv4.tcp_fack = 1,　　# Turn on the tcp_timestamps,　　net.ipv4.tcp_timestamps = 1,　　# Enable TCP SYN Cookie Protection,　　net.ipv4.tcp_syncookies = 1,　　# Enable ignoring broadcasts request,　　net.ipv4.icmp_echo_ignore_broadcasts = 1,　　# Enable bad error message Protection,　　net.ipv4.icmp_ignore_bogus_error_responses = 1,　　# Make more local ports available,　　# net.ipv4.ip_local_port_range = 1024 65000,　　# Set TCP Re-Ordering value in kernel to ‘5′,　　net.ipv4.tcp_reordering = 5,　　# Lower syn retry rates,　　net.ipv4.tcp_synack_retries = 2,　　net.ipv4.tcp_syn_retries = 3,　　# Set Max SYN Backlog to ‘2048′,　　net.ipv4.tcp_max_syn_backlog = 2048,　　# Various Settings,　　net.core.netdev_max_backlog = 1024,　　# Increase the maximum number of skb-heads to be cached,　　net.core.hot_list_length = 256,　　# Increase the tcp-time-wait buckets pool size,　　net.ipv4.tcp_max_tw_buckets = 360000,　　# This will increase the amount of memory available for socket input/output queues,　　net.core.rmem_default = 65535,　　net.core.rmem_max = 8388608,　　net.ipv4.tcp_rmem = 4096 87380 8388608,　　net.core.wmem_default = 65535,　　net.core.wmem_max = 8388608,　　net.ipv4.tcp_wmem = 4096 65535 8388608,　　net.ipv4.tcp_mem = 8388608 8388608 8388608,　　net.core.optmem_max = 40960,　　如果希望屏蔽别人 ping 你的主机，则加入以下代码：,　　# Disable ping requests,