三、调整操作系统相应服务和参数

1. 禁用 SELINUX
   setenforce 0
   sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
   getenforce
   修改为 DISABLE

2. 关闭Transparent HugePages
   修改/etc/grub.conf文件，在Kernel行末尾加上下列参数：
   transparent_hugepage=never

3. IO调度算法调整
   修改/etc/grub.conf文件，在Kernel行末尾加上下列参数：
   elevator=deadline
   可以通过cat /sys/block/sda/queue/scheduler命令来查看目前调度算法。

4. 配置服务
   service iptables stop
   service iptables save
   service ip6tables stop
   service ip6tables save
   chkconfig avahi-daemon off
   chkconfig bluetooth off
   chkconfig cpuspeed off
   chkconfig cups off
   chkconfig firstboot off
   chkconfig ip6tables off
   chkconfig iptables off
   chkconfig pcmcia off

5. 内核参数修改
   cat>>/etc/sysctl.conf<<EOF
   kernel.shmmax = 54050481766
   kernel.shmall = 16494898
   kernel.shmmni = 4096
   kernel.sem = 250 32000 100 128
   fs.file-max = 6815744
   fs.aio-max-nr = 4194304
   net.ipv4.ip_local_port_range = 9000 65500
   net.core.rmem_default = 262144
   net.core.rmem_max = 4194304
   net.core.wmem_default = 262144
   net.core.wmem_max = 1048576
   net.ipv4.ipfrag_high_thresh = 16777216
   net.ipv4.ipfrag_low_thresh = 15728640
   kernel.randomize_va_space=0
   vm.min_free_kbytes = 524288
   # vm.nr_hugepages = 512
   EOF
   最佳配置算法:
   #shmmax
   echo "`cat /proc/meminfo | grep "MemTotal" | awk '{print $2}'` * 1024 * 0.8" | bc  | sed 's#\..*$##'
   #shmall
   echo "`cat /proc/meminfo | grep "MemTotal" | awk '{print $2}'` / (`getconf PAGESIZE` / 1024)" | bc
   使参数生效
   sysctl -p

6. Limits配置
   cat>>/etc/security/limits.conf<<EOF
   oracle  soft    nproc           2047
   oracle  hard    nproc           16384
   oracle  soft    nofile          1024
   oracle  hard    nofile          65536
   oracle  soft    stack           10240
   oracle  hard    stack           32768
   root    soft    stack           10240
   root    hard    stack           32768
   *       soft    memlock         unlimited
   *       hard    memlock         unlimited
   EOF

7. PAM 调整
   echo "session required pam_limits.so" >>/etc/pam.d/login