服务器的负载能力，很大程度上取决于系统管理员的配置和优化能力。相同的硬件、不同的软件配置，会造成截然不同的效果。下面我将给大家介绍一下如何优化 sysctrl, Apache 以及 mysql 。请注意，所有配置均为取决于个人，请根据自己的实际情况做调整。 配置Sysctl 编辑此文件： nano -w /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 net.ipv4.icmp_echo_ignore_all = 1 编辑完成后，请执行以下命令使变动立即生效： /sbin/sysctl -p /sbin/sysctl -w net.ipv4.route.flush=1 MySQL优化 编辑MySQL的配置文件： nano /etc/my.cnf 输入以下内容： [mysqld] connect_timeout=15 interactive_timeout=100 join_buffer_size=1M key_buffer=128M max_allowed_packet=16M max_connections=500 max_connect_errors=10 myisam_sort_buffer_size=64M read_buffer_size=1M read_rnd_buffer_size=768K sort_buffer_size=1M table_cache=1024 thread_cache_size=100 thread_concurrency=4 wait_timeout=300 query_cache_size=32M query_cache_limit=1M query_cache_type=1 skip-innodb 请注意，以上配置适用于512M~1024M内存，如内存更大的话请自行做调整。给项目增加内存会加快速度，但是使用过多的内存而导致启用swap的话，会极大的导致系统效率下降。其中 thread_concurrency 这项配置，单CPU的话请设置为2，双CPU的话请设置为4。 Apache优化 以下优化适用于 Apache 1.3 系列，如果你用的是 2.0 系列的话，请自行做调整和判断。 确认 Apache 的配置文件位置并开始编辑： locate httpd.conf nano -w /path/to/httpd.conf httpd.conf的文件有许多内容，笔者就拿出需要做优化的： KeepAlive On MaxKeepAliveRequests 1000 KeepAliveTimeout 3 MinSpareServers 8 MaxSpareServers 13 MaxRequestsPerChild 50 将 KeepAliveTimeout 设定到较小的数字将有助于减少服务器上的无用等待链接，一定程度上能增加服务器负载。 另外，下面这条不算优化，但是是Apache安全相关： ServerSignature Off ServerTokens ProductOnly 将 ServerSignature 关闭，并增加 ServerTokens ProductOnly 可以使常人无法检测到Apache的实际版本号，有助于Apache的安全。 以上所做的这些优化在某种程度上会增强服务器的负载性能。但请注意，最佳的配置是实践出来的。
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