1.修改 Max processes 或者 files (Max processes，Max open files )
(1)方法一：修改配置文件 /etc/security/limits.d/90-nproc.conf 
   使用vi /etc/security/limits.d/90-nproc.conf  命令
*          soft    nproc     1024
改为:
*          soft    nproc     65536
然后重启MongoDB的相关服务即可
(2)方法二：修改配置文件 /etc/security/limits.conf
 使用vi /etc/security/limits.conf 命令
*  soft   nofile 65536
*  hard   nofile 65536
*  soft   nproc 65536
*  hard  nproc 65536


重启 mongod 服务


查看系统限制：ulimit -a
MongoDB推荐配置:
ulimit -f unlimited
ulimit -t unlimited
ulimit -v unlimited
ulimit -n 64000
ulimit -m unlimited
ulimit -u 64000


2.关闭透明大页功能
禁用透明大页的方法：
(1).修改文件/etc/grub.conf,添加一行：transparent_hugepage=never
(2)修改文件/etc/rc.local文件，添加：
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
   echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
   echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi


3.修改磁盘调度算法:
echo deadline > /sys/block/sda/queue/scheduler


4.设置Linux内核参数:
vi /etc/sysctl.conf
net.ipv4.ip_forward = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 483183820800
kernel.shmall = 117964800
net.ipv4.tcp_max_tw_buckets = 180000
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 262144
net.core.somaxconn = 262144
net.ipv4.tcp_syn_retries = 3
net.ipv4.tcp_retries2 = 5
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.ip_local_port_range = 1024 65535
vm.zone_reclaim_mode = 0
vm.dirty_writeback_centisecs = 400
vm.dirty_expire_centisecs = 2400
vm.dirty_background_ratio = 5
vm.dirty_ratio = 20
vm.drop_caches = 1
vm.min_free_kbytes = 52428800
vm.vfs_cache_pressure = 200
fs.file-max = 98000
kernel.pid_max = 64000
kernel.threads-max = 64000