NetworkManager-wait-online.service 在启动时失败，它延迟了我的启动
我的启动非常慢，我不知道为什么。
$ systemd-analyze
Startup finished in 10.975s (kernel) + 49.732s (userspace) = 1min 708ms
$ systemd-analyze blame
34.971s apt-daily.service
20.590s snapd.refresh.service
17.113s grub-common.service
16.033s apport.service
16.027s networking.service
15.894s ondemand.service
15.860s irqbalance.service
15.655s speech-dispatcher.service
11.695s ModemManager.service
9.772s accounts-daemon.service
8.626s NetworkManager-wait-online.service
8.058s systemd-logind.service
8.053s bluetooth.service
7.944s gpu-manager.service
7.896s alsa-restore.service
7.892s pppd-dns.service
7.882s rsyslog.service
7.860s avahi-daemon.service
7.844s dev-sda1.device
7.842s systemd-user-sessions.service
7.648s lightdm.service
7.610s teamviewerd.service
6.445s apparmor.service
此外，在启动过程中，我看到一条消息，内容如下：
device descriptor read/all, error -62
ata1 softreset failed (device not ready) #most of the times
error …18.04 的启动似乎比 17.10 需要更长的时间，所以我跑了systemd-analyze blame发现，apt-daily.service并且apt-daily-upgrade.service在它们之间占用了超过三分钟的时间。
:~$ systemd-analyze time
Startup finished in 9.173s (kernel) + 3min 30.201s (userspace) = 3min 39.375s
graphical.target reached after 15.268s in userspace
:~$ systemd-analyze blame
1min 52.265s apt-daily-upgrade.service
1min 27.579s apt-daily.service
6.603s NetworkManager-wait-online.service
5.105s plymouth-quit-wait.service
1.517s plymouth-start.service
1.439s dev-sda1.device.............
那么，这些服务实际上在做什么（我想检查 apt 是否是最新的），为什么它们需要这么长时间，我是否真的需要它们在每次启动时运行？
自从几天前从 14.10 升级到 15.04 以来，grub OS 屏幕到登录屏幕的启动时间从 12 秒增加到大约 40 秒。这是我的systemd-analyze 关键链输出：
The time after the unit is active or started is printed after the "@" character.
The time the unit takes to start is printed after the "+" character.
graphical.target @37.433s
??multi-user.target @37.433s
??getty.target @37.432s
??getty@tty1.service @37.432s
??systemd-user-sessions.service @35.906s +9ms
??remote-fs.target @35.904s
??media-XalnasStorage.mount @35.849s +53ms
??network-online.target @35.846s
??network.target @11.636s
??NetworkManager.service @11.502s +132ms
??basic.target @11.487s
??sockets.target @11.487s
??avahi-daemon.socket @11.487s
??sysinit.target @11.485s
??networking.service @11.333s +65ms
??apparmor.service @11.269s +63ms
??local-fs.target …我最近将我的 ubuntu 更新到 20.04。现在需要很长时间才能启动。我有 I5 CPU 和 8G RAM。
这里的cmd systemd-analyze blame 输出：
1min 30.094s nmbd.service
47.725s plymouth-quit-wait.service
22.834s udisks2.service
22.771s networkd-dispatcher.service
19.079s snapd.service
16.775s dev-sda6.device
16.618s accounts-daemon.service
15.567s NetworkManager-wait-online.service
11.738s polkit.service
11.591s avahi-daemon.service
11.590s bluetooth.service
11.498s NetworkManager.service
10.792s switcheroo-control.service
10.786s thermald.service
10.782s systemd-logind.service
10.780s wpa_supplicant.service
9.671s ModemManager.service
7.797s dev-loop0.device
7.371s dev-loop1.device
6.890s dev-loop2.device
6.884s fwupd.service
6.669s dev-loop4.device
5.474s systemd-journal-flush.service
5.311s dev-loop3.device
5.240s bolt.service
4.621s systemd-resolved.service
4.481s ufw.service
3.997s rsyslog.service
3.761s apport.service
3.673s gpu-manager.service
3.362s systemd-udevd.service
3.018s grub-common.service
2.985s e2scrub_reap.service …所以我在我的笔记本电脑上安装了 Ubuntu 22.04.2 LTS。启动需要 2 分钟以上，这对我来说似乎太长了。几个月前，当我在我的机器上安装 Ubuntu 时，并没有花费这么多时间。以下是分别由“systemd-analyze”和“system-analyzeblame”生成的日志
\nisaac@Isaac-Lenovo-IdeaPad-S145-15AST:~$ systemd-analyze \nStartup finished in 4.979s (firmware) + 8.472s (loader) + 4.847s (kernel) + 1min 59.732s (userspace) = 2min 18.032s graphical.target reached after 1min 59.606s in userspace
isaac@Isaac-Lenovo-IdeaPad-S145-15AST:~$ systemd-analyze blame\n1min 22.046s fstrim.service
57.290s plymouth-quit-wait.service\n 37.756s systemd-journal-flush.service\n 33.487s dev-mapper-vgubuntu\\x2droot.device\n 31.672s apt-daily.service\n 26.775s snapd.service\n 23.608s logrotate.service\n 21.060s networkd-dispatcher.service\n 20.841s snap-bare-5.mount\n 19.967s snap-core18-2714.mount\n 19.579s NetworkManager-wait-online.service\n 19.316s snap-core18-2721.mount\n 18.666s udisks2.service\n 18.013s snap-core20-1778.mount\n 16.502s snap-core20-1852.mount\n 13.452s snap-core22-583.mount\n 13.435s ModemManager.service\n 13.344s …