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) 0data seg size (kbytes, -d) unlimitedscheduling priority (-e) 0file size (blocks, -f) unlimitedpending signals (-i) 3791max locked memory (kbytes, -l) 64max memory size (kbytes, -m) unlimitedopen files (-n) 1024 #还是默认值1024pipe size (512 bytes, -p) 8POSIX message queues (bytes, -q) 819200real-time priority (-r) 0stack size (kbytes, -s) 8192cpu time (seconds, -t) unlimitedmax user processes (-u) 3791virtual memory (kbytes, -v) unlimitedfile locks (-x) unlimited[root@bogon ~]# rebootConnection 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 192.168.1.100u[root@bogon ~]# ulimit -acore file size (blocks, -c) 0data seg size (kbytes, -d) unlimitedscheduling priority (-e) 0file size (blocks, -f) unlimitedpending signals (-i) 3791max locked memory (kbytes, -l) 64max memory size (kbytes, -m) unlimitedopen files (-n) 1024000 #重启后生效了pipe size (512 bytes, -p) 8POSIX message queues (bytes, -q) 819200real-time priority (-r) 0stack size (kbytes, -s) 8192cpu time (seconds, -t) unlimitedmax user processes (-u) 1024000virtual memory (kbytes, -v) unlimitedfile 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