Ubuntu 优化启动时间优化

优化 Ubuntu 20.04 的启动时间可以从多个方面入手，以下是详细的步骤和建议：

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一、分析启动耗时

首先检查系统启动各阶段的耗时：

systemd-analyze time        # 查看整体启动时间
systemd-analyze blame       # 列出各服务/进程的启动耗时
systemd-analyze critical-chain  # 查看关键路径的启动链

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二、禁用不必要的服务

禁用启动时不需要的系统服务：

sudo systemctl disable <service-name>  # 禁用服务（如蓝牙、打印机等）
sudo systemctl mask <service-name>     # 彻底屏蔽服务（谨慎使用）

常见可禁用的服务：

• bluetooth.service（蓝牙）
• cups.service（打印机）
• ModemManager.service（调制解调器）
• networkd-dispatcher.service（若使用NetworkManager）
• accounts-daemon.service（用户账户管理）

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三、优化文件系统检查（fsck）

1. 减少文件系统检查频率：

   • 编辑 /etc/fstab，将最后一列的数值改为 0（表示不检查）：

     sudo nano /etc/fstab
     # 示例：将最后数字从 1 或 2 改为 0
     UUID=xxxx / ext4 defaults,noatime,discard 0 0
     

   • 使用 noatime 或 relatime 挂载选项减少磁盘写入。

2. 禁用启动时的文件系统等待：

   sudo systemctl disable systemd-fsck-root.service
   

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四、调整内核参数

1. 编辑 GRUB 配置：

   sudo nano /etc/default/grub
   # 修改以下参数：
   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
   # 添加或修改为（例如）：
   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash noresume fsck.mode=skip"
   

   • fsck.mode=skip：跳过文件系统检查（谨慎使用）。
   • noresume：如果未使用休眠功能。

2. 更新 GRUB：

   sudo update-grub
   

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五、优化 SSD 性能（如使用 SSD）

1. 启用 TRIM：

   sudo systemctl enable fstrim.timer
   

2. 确认是否已启用 discard 选项（在 /etc/fstab 中添加 discard）。

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六、清理启动项

1. 管理用户级启动程序：

   gnome-session-properties  # 图形界面管理启动项
   

2. 清理旧内核：

   sudo apt autoremove --purge  # 删除旧内核和依赖
   

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七、排查硬件问题

1. 检查硬盘健康状况：

   sudo smartctl -a /dev/sda
   

2. 检查日志中的硬件错误：

   journalctl -b -p 3  # 查看本次启动的错误日志
   

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八、使用轻量化组件

• 替换图形界面为轻量级桌面（如 Xfce 或 LXQt）。
• 使用更快的显示管理器（如 lightdm 替代 gdm3）：

  sudo apt install lightdm
  sudo dpkg-reconfigure lightdm
  

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九、其他优化

1. 减少 GRUB 等待时间：

   sudo nano /etc/default/grub
   GRUB_TIMEOUT=2  # 将默认超时时间改为2秒
   sudo update-grub
   

2. 预加载内核模块：
   • 将常用模块添加到 /etc/modules-load.d/modules.conf。

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十、验证优化结果

重启后再次运行：

systemd-analyze time
systemd-analyze blame

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通过以上步骤，大部分情况下可以显著缩短启动时间。如果问题依旧存在，可能需要进一步排查特定服务或硬件兼容性问题。

我的结果:

1. 最开始的时候：

> systemd-analyze time
Startup finished in 22.227s (firmware) + 9.423s (loader) + 36.324s (kernel) + 1min 51.738s (userspace) = 2min 59.713s 
graphical.target reached after 1min 51.722s in userspace
> systemd-analyze blame
20.870s plymouth-quit-wait.service                                             >4.621s NetworkManager-wait-online.service                                     >3.019s dev-sda2.device                                                        >1.329s fwupd.service                                                          >459ms docker.service                                                         >391ms snapd.service                                                          >387ms man-db.service                                                         >305ms blueman-mechanism.service                                              >299ms systemd-logind.service                                                 >278ms dev-loop0.device                                                       >267ms logrotate.service                                                      >264ms upower.service                                                         >255ms snap-core22-1722.mount                                                 >241ms snap-core20-2496.mount                                                 >239ms dev-loop2.device                                                       >235ms snap-gnome\x2d3\x2d28\x2d1804-198.mount                                >234ms containerd.service                                                     >232ms snap-gnome\x2d3\x2d38\x2d2004-143.mount                                >232ms snap-gnome\x2d42\x2d2204-176.mount                                     >229ms snap-gnome\x2d42\x2d2204-202.mount                                     >227ms snap-gtk\x2dcommon\x2dthemes-1535.mount                                >226ms dev-loop11.device                                                      >> systemd-analyze critical-chain
The time when unit became active or started is printed after the "@" character.
The time the unit took to start is printed after the "+" character.graphical.target @1min 51.722s
└─multi-user.target @1min 51.722s└─kerneloops.service @1min 35.442s +13ms└─nss-lookup.target @1min 35.440s└─todeskd.service @1min 35.439s└─network-online.target @1min 35.436s└─NetworkManager-wait-online.service @1min 30.814s +4.621s└─NetworkManager.service @1min 30.736s +71ms└─dbus.service @1min 30.733s└─basic.target @1min 30.712s└─sockets.target @1min 30.712s└─uuidd.socket @1min 30.710s└─sysinit.target @1min 30.699s└─systemd-timesyncd.service @3.507s +97ms└─systemd-tmpfiles-setup.service @3.486s +16ms└─systemd-journal-flush.service @562ms +106ms└─systemd-journald.service @458ms +103ms└─systemd-journald.socket @451ms└─system.slice @445ms└─-.slice @445ms

2. 优化了一下启动项的图像加载，禁用了plymouth图像加载

 5263  sudo systemctl mask plymouth-quit-wait.service5264  sudo apt remove plymouth5265  sudo nano /etc/default/grub5266  sudo update-grub

> systemd-analyze time
Startup finished in 20.682s (firmware) + 5.135s (loader) + 4.417s (kernel) + 1min 37.067s (userspace) = 2min 7.302s 
graphical.target reached after 1min 37.059s in userspace
> systemd-analyze blame
4.897s NetworkManager-wait-online.service                                      >
1.456s fwupd.service                                                           >
1.328s docker.service                                                          >711ms dev-sda2.device                                                         >681ms snapd.seeded.service                                                    >620ms man-db.service                                                          >594ms snapd.service                                                           >504ms networkd-dispatcher.service                                             >419ms blueman-mechanism.service                                               >322ms dev-loop0.device                                                        >298ms dev-loop1.device                                                        >298ms apport-autoreport.service                                               >293ms containerd.service                                                      >292ms dev-loop2.device                                                        >287ms upower.service                                                          >279ms logrotate.service                                                       >270ms systemd-logind.service                                                  >269ms dev-loop4.device                                                        >256ms dev-loop8.device                                                        >252ms dev-loop10.device                                                       >249ms dev-loop5.device                                                        >247ms dev-loop6.device                                                        >242ms accounts-daemon.service                                                 >241ms dev-loop3.device                                                        >236ms snap-core18-2846.mount                                                  >232ms fstrim.service                                                          >221ms udisks2.service                                                         >218ms snap-gnome\x2d42\x2d2204-176.mount                                      >217ms snap-gnome\x2d42\x2d2204-202.mount                                      >213ms dev-loop9.device                                                        >213ms dev-loop11.device                                                       >208ms snap-snap\x2dstore-1113.mount                                           >205ms snap-snapd-23545.mount                                                  >204ms dev-loop17.device                                                       >204ms dev-loop18.device                                                       >204ms snap-snapd-23771.mount                                                  >197ms dev-loop16.device                                                       >197ms dev-loop7.device                                                        >188ms dev-loop15.device                                                       >186ms systemd-resolved.service                                                >185ms smartmontools.service                                                   >182ms snap-core20-2496.mount                                                  >180ms snap-core22-1722.mount                                                  >179ms snap-core22-1748.mount                                                  >175ms snap-gnome\x2d3\x2d38\x2d2004-119.mount                                 >172ms dev-loop13.device                                                       >172ms snap-snap\x2dstore-1216.mount                                           >168ms systemd-timesyncd.service                                               >165ms snap-notion\x2dsnap\x2dreborn-49.mount                                  >164ms dev-loop14.device                                                       >161ms dev-loop12.device                                                       >150ms lm-sensors.service                                                      >146ms apparmor.service                                                        >136ms systemd-udev-trigger.service                                            >136ms gpu-manager.service                                                     >135ms ModemManager.service                                                    >134ms snap-core18-2855.mount                                                  >120ms avahi-daemon.service                                                    >116ms bluetooth.service                                                       >116ms systemd-journal-flush.service                                           >114ms snap-gtk\x2dcommon\x2dthemes-1535.mount                                 >111ms NetworkManager.service                                                  >110ms snap-notion\x2dsnap\x2dreborn-50.mount                                  >109ms systemd-journald.service                                                >103ms polkit.service                                                          >> systemd-analyze critical-chain
The time when unit became active or started is printed after the "@" character.
The time the unit took to start is printed after the "+" character.graphical.target @1min 37.059s
└─multi-user.target @1min 37.059s└─docker.service @1min 35.730s +1.328s└─nss-lookup.target @1min 35.729s└─todeskd.service @1min 35.729s└─network-online.target @1min 35.726s└─NetworkManager-wait-online.service @1min 30.829s +4.897s└─NetworkManager.service @1min 30.714s +111ms└─dbus.service @1min 30.708s└─basic.target @1min 30.688s└─sockets.target @1min 30.688s└─snapd.socket @1min 30.686s +1ms└─sysinit.target @1min 30.671s└─systemd-timesyncd.service @1.249s +168ms└─systemd-tmpfiles-setup.service @1.207s +37ms└─systemd-journal-flush.service @584ms +116ms└─systemd-journald.service @473ms +109ms└─systemd-journald.socket @466ms└─system.slice @461ms└─-.slice @461ms