方法一：

[root@bogon ~]# vi /etc/systemd/system.conf

[root@bogon ~]# cat /etc/systemd/system.conf

#  This file is part of systemd.

#

#  systemd is free software; you can redistribute it and/or modify it

#  under the terms of the GNU Lesser General Public License as published by

#  the Free Software Foundation; either version 2.1 of the License, or

#  (at your option) any later version.

#

# Entries in this file show the compile time defaults.

# You can change settings by editing this file.

# Defaults can be restored by simply deleting this file.

#

# See systemd-system.conf(5) for details.

[Manager]

#LogLevel=info

#LogTarget=journal-or-kmsg

#LogColor=yes

#LogLocation=no

#DumpCore=yes

#CrashShell=no

#ShowStatus=yes

#CrashChVT=1

#CPUAffinity=1 2

#JoinControllers=cpu,cpuacct net_cls,net_prio

#RuntimeWatchdogSec=0

#ShutdownWatchdogSec=10min

#CapabilityBoundingSet=

#SystemCallArchitectures=

#TimerSlackNSec=

#DefaultTimerAccuracySec=1min

#DefaultStandardOutput=journal

#DefaultStandardError=inherit

#DefaultTimeoutStartSec=90s

#DefaultTimeoutStopSec=90s

#DefaultRestartSec=100ms

#DefaultStartLimitInterval=10s

#DefaultStartLimitBurst=5

#DefaultEnvironment=

#DefaultCPUAccounting=no

#DefaultBlockIOAccounting=no

#DefaultMemoryAccounting=no

#DefaultLimitCPU=

#DefaultLimitFSIZE=

#DefaultLimitDATA=

#DefaultLimitSTACK=

#DefaultLimitCORE=

#DefaultLimitRSS=

#DefaultLimitNOFILE=

DefaultLimitNOFILE=1024000      #这里需要修改

#DefaultLimitAS=

#DefaultLimitNPROC=

DefaultLimitNPROC=1024000   #这里也需要修改

#DefaultLimitMEMLOCK=

#DefaultLimitLOCKS=

#DefaultLimitSIGPENDING=

#DefaultLimitMSGQUEUE=

#DefaultLimitNICE=

#DefaultLimitRTPRIO=

#DefaultLimitRTTIME=

[root@bogon ~]# ulimit -a      #修改之后没有重启

core file size          (blocks, -c) 0

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 3791

max locked memory       (kbytes, -l) 64

max memory size         (kbytes, -m) unlimited

open files                      (-n) 1024   #还是默认值1024

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) 8192

cpu time               (seconds, -t) unlimited

max user processes              (-u) 3791

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited

[root@bogon ~]# reboot

Connection to 192.168.1.107 closed by remote host.

Connection to 192.168.1.107 closed.

root@BP:~# ssh 192.168.1.107    #我使用的是密钥登录，所以不用再输入密码

Last login: Mon Jun 26 15:38:21 2017 from 192.168.1.100

u[root@bogon ~]# ulimit -a

core file size          (blocks, -c) 0

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 3791

max locked memory       (kbytes, -l) 64

max memory size         (kbytes, -m) unlimited

open files                      (-n) 1024000     #重启后生效了

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) 8192

cpu time               (seconds, -t) unlimited

max user processes              (-u) 1024000

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited

[root@bogon ~]#


方法二：

ulimit只能做临时修改，重启后失效。
可以加入
ulimit -SHn 65535
到 /etc/rc.local 每次启动启用。

终极解除 Linux 系统的最大进程数和最大文件打开数限制：
vim /etc/security/limits.conf
# 添加如下的行
* soft nproc 11000
* hard nproc 11000
* soft nofile 655350
* hard nofile 655350