查看内核、用户空间、Unit启动时间

systemd-analyze time：查看内核、用户空间启动所需的时间

[[email protected] ~]# systemd-analyze time
Startup finished in 1.068s (kernel) + 3.842s (initrd) + 52.848s (userspace) = 57.759s

systemd-analyze time：查看Unit启动所需的时间，就是系统在启动过程中在屏幕显示的信息

[[email protected] ~]# systemd-analyze blame
18.281s libvirtd.service
6.356s firewalld.service
6.194s polkit.service
6.063s systemd-udev-settle.service
5.248s kdump.service
5.075s lvm2-monitor.service
4.922s dev-mapper-centos\x2droot.device
4.524s NetworkManager-wait-online.service
4.497s gssproxy.service
4.494s ksm.service
4.358s avahi-daemon.service
4.324s rhel-dmesg.service
4.316s bluetooth.service
4.298s rsyslog.service
3.657s tuned.service
3.589s postfix.service
2.673s [email protected]:2.service
2.254s abrt-ccpp.service
1.587s ModemManager.service
1.506s proc-fs-nfsd.mount
1.380s NetworkManager.service
1.341s systemd-tmpfiles-setup-dev.service
1.229s sysstat.service
1.061s rhel-readonly.service
1.023s boot.mount
893ms sshd.service
832ms systemd-udevd.service
738ms network.service
668ms systemd-logind.service
542ms systemd-sysctl.service
531ms auditd.service
526ms sys-kernel-debug.mount
514ms kmod-static-nodes.service
420ms dev-hugepages.mount
408ms home.mount
388ms rhel-import-state.service
378ms iscsi-shutdown.service
357ms ksmtuned.service
348ms plymouth-quit.service
307ms systemd-journald.service
306ms plymouth-quit-wait.service
300ms dmraid-activation.service
273ms dev-mqueue.mount
251ms plymouth-read-write.service
234ms rpc-statd-notify.service
233ms systemd-remount-fs.service
216ms [email protected]
214ms systemd-udev-trigger.service
205ms systemd-journal-flush.service
199ms nfs-config.service
194ms systemd-random-seed.service
162ms systemd-user-sessions.service
151ms dev-mapper-centos\x2dswap.swap
141ms systemd-tmpfiles-setup.service
110ms systemd-vconsole-setup.service
107ms vsftpd.service
40ms plymouth-start.service
36ms systemd-update-utmp.service
28ms blk-availability.service
22ms systemd-fsck-root.service
14ms systemd-update-utmp-runlevel.service
11ms var-lib-nfs-rpc_pipefs.mount
6ms sys-kernel-config.mount

参考资料：
Systemd Boot Process a Close Look in Linux