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。