Ubuntu 16.04启动速度过慢求助：启动时长约95秒

Hey Johnnyf, sorry to hear your Ubuntu 16.04 is dragging its feet on boot—95 seconds is way longer than it should be. Let’s walk through some practical steps to diagnose and fix this, starting with digging into those startup logs you mentioned.

First, Pinpoint the Culprits with Systemd Tools #

Ubuntu 16.04 uses systemd, so we can use built-in commands to see exactly what’s eating up boot time:

1. Check overall boot breakdown
   Run this in the terminal to get a high-level view of where time is spent:

   systemd-analyze
   

   It’ll show you time spent in kernel space, user space, and total boot time.

2. Identify the slowest services
   This command lists services ordered by how long they take to start—focus on the top 10-15 entries:

   systemd-analyze blame
   

   Common offenders here are things like network services timing out, disk checks taking too long, or unnecessary services you don’t even use.

3. Map the critical boot chain
   This shows the sequence of services that directly impact boot time—look for any services marked with * that have long delays:

   systemd-analyze critical-chain
   

Common Fixes for Slow Boot on Ubuntu 16.04 #

1. Fix Network-Related Delays #

If you see services like systemd-networkd.service or networking.service taking ages, it’s often due to waiting for a network connection that isn’t available (e.g., trying to connect to a Wi-Fi network that’s off, or DHCP timeouts):

• If you don’t need network connectivity on boot (e.g., you use a laptop and connect manually later), disable the service:

  sudo systemctl disable networking.service
  

• For DHCP issues, edit your network config to use a static IP if possible, or adjust the timeout settings in /etc/network/interfaces.

2. Disable Unnecessary Startup Services #

Lots of services run on boot that you might never use. For example:

• Bluetooth (if you don’t use a Bluetooth device):

  sudo systemctl disable bluetooth.service
  

• Printing services (if you don’t have a printer):

  sudo systemctl disable cups.service
  

• Remote desktop services (like VNC) if you don’t use them:

  sudo systemctl disable vncserver@.service
  

Always double-check that you don’t need a service before disabling it!

3. Check for Disk Issues #

Slow boot can also be caused by a failing hard drive or filesystem errors.

• Run a filesystem check (you’ll need to reboot to do this, as the disk can’t be mounted during the check):

  sudo touch /forcefsck
  sudo reboot
  

  The system will run fsck on boot—let it finish, then check if boot time improves.
• If you’re using an HDD, consider upgrading to an SSD (this is one of the biggest boot speed boosts you can get!).

4. Fix Swap-Related Delays #

If your swap partition is slow or misconfigured, it can add boot time. Check if swap is active:

swapon --show

If you don’t need swap (or have enough RAM), disable it:

sudo systemctl disable swap.target

Or, if you do need swap, make sure your swap partition is properly formatted and listed in /etc/fstab.

Next Steps #

If you can share the output of systemd-analyze blame (just the top 10 entries) or the specific "conflicting startup nodes" from your logs, I can give you more targeted advice. For example, if a service is failing and retrying multiple times, we can adjust its timeout or disable it entirely.

Hang in there—we’ll get that boot time down to something reasonable!

内容的提问来源于stack exchange，提问作者johnnyf