把Windows改造成Linux 后，发现启动速度很慢
使用systemd-analyze分析后，结果如下：
root@lmint:~# systemd-analyze
Startup finished in 2min 4.534s (kernel) + 1min 23.405s (userspace) = 3min 27.939s
graphical.target reached after 1min 21.910s in userspace.
root@lmint:~# 进一步分析：
root@lmint:~# systemd-analyze blame
47.340s systemd-udev-settle.service
21.411s e2scrub_reap.service
18.399s logrotate.service
15.014s blueman-mechanism.service
9.687s NetworkManager.service -- 不可处理
9.168s dev-sda3.device
8.463s accounts-daemon.service -- 不可处理
8.232s udisks2.service -- 自动mount U盘的服务
7.226s power-profiles-daemon.service
7.044s dpkg-db-backup.service
6.991s polkit.service
6.959s NetworkManager-wait-online.service
6.433s avahi-daemon.service
6.414s dbus.service
6.147s systemd-journal-flush.service
5.394s switcheroo-control.service
5.388s thermald.service
4.880s ubuntu-system-adjustments.service
4.843s lvm2-monitor.service
3.818s systemd-udevd.service
3.072s systemd-tmpfiles-setup-dev-early.service
2.824s ModemManager.service
2.679s plymouth-start.service
2.658s systemd-sysctl.service
2.351s systemd-modules-load.service
2.289s rsyslog.service
1.983s gpu-manager.service
1.919s zfs-load-module.service
1.790s apparmor.service
1.653s grub-common.service
1.606s cups.service
1.492s casper-md5check.service
1.265s systemd-resolved.service
969ms lightdm.service
959ms plymouth-quit-wait.service随后，查看官方对这些服务的解释说明，将可以disable的服务，disable后，再次启动。速度快了很多。
adminuser@lmint:~/Desktop$ systemd-analyze
Startup finished in 3.175s (kernel) + 42.275s (userspace) = 45.450s
graphical.target reached after 33.788s in userspace.
adminuser@lmint:~/Desktop$ END