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--- ubuntu:boot:speed_up_boot [2019/11/25 22:06] – created peter
+++ ubuntu:boot:speed_up_boot [2020/07/15 09:30] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-Ubuntu - Boot - Speed up boot
+====== Ubuntu - Boot - Speed up boot ======
+===== Check startup time =====
+Check how long it takes to boot:
+<code bash>
+systemd-analyze time
+</code>
+returns:
+<code bash>
+Startup finished in 16.619s (firmware) + 10.201s (loader) + 36.729s (kernel) + 41.034s (userspace) = 1min 44.586s
+graphical.target reached after 23.396s in userspace
+</code>
+This shows how long it takes for the Linux kernel and base system services to load.
+It shows you how much time is required, from the moment the kernel is loaded until you are dropped to the Linux console.
+It doesn’t account for the time your graphical interface requires to boot up.
+----
+===== Check startup time for the graphical interface to initialize =====
+You can also see the time required by the graphical interface to initialize with this command:
+<code bash>
+systemd-analyze critical-chain graphical.target
+</code>
+returns
+<code bash>
+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 @23.396s
+└─multi-user.target @23.396s
+  └─libvirt-guests.service @23.378s +18ms
+    └─libvirtd.service @3.189s +20.187s
+      └─network.target @3.189s
+        └─NetworkManager.service @2.333s +855ms
+          └─dbus.service @2.223s
+            └─basic.target @2.207s
+              └─sockets.target @2.207s
+                └─docker.socket @2.206s +965us
+                  └─sysinit.target @2.203s
+                    └─apparmor.service @1.458s +745ms
+                      └─local-fs.target @1.457s
+                        └─run-user-1000-gvfs.mount @15.641s
+                          └─run-user-1000.mount @14.700s
+                            └─swap.target @1.607s
+                              └─dev-mapper-ubuntu\x2d\x2dvg\x2dswap_1.swap @1.565s +36ms
+                                └─dev-mapper-ubuntu\x2d\x2dvg\x2dswap_1.device @1.565s
+</code>
+This shows that the graphical user interface loaded in 23.396 seconds.
+<WRAP info>
+This doesn’t account for the time required to load desktop utilities.
+To enable/disable those, launch your desktop environment startup manager.
+</WRAP>
+----
+===== Check which services takes most time =====
+Use the following command to check which service takes most of time
+<code bash>
+systemd-analyze blame
+</code>
+returns
+<code bash>
+.898s apt-daily.service
+.417s rsyslog.service
+.187s libvirtd.service
+.774s systemd-networkd-wait-online.service
+.654s docker.service
+.841s apt-daily-upgrade.service
+.820s snapd.service
+.487s plymouth-quit-wait.service
+ms dev-mapper-ubuntu\x2d\x2dvg\x2droot.device
+ms NetworkManager.service
+ms fwupd.service
+ms udisks2.service
+ms apparmor.service
+ms networkd-dispatcher.service
+ms snap-gnome\x2dcalculator-544.mount
+ms networking.service
+ms thermald.service
+ms snap-netbeans-10.mount
+ms snap-gnome\x2dlogs-81.mount
+ms systemd-resolved.service
+ms systemd-timesyncd.service
+ms systemd-logind.service
+ms ModemManager.service
+ms apport.service
+ms gpu-manager.service
+ms motd-news.service
+ms grub-common.service
+...
+</code>
+<WRAP info>
+You can navigate the list with your arrow keys or **PAGE UP** and **PAGE DOWN**.
+Press **q** to quit.
+</WRAP>
+----
+===== Check the critical chain =====
+Analyze each major process to determine how long it takes to run.
+For example, to get further information on the AppArmor Service, to see if you can disable it or speed it up, use:
+<code bash>
+systemctl status apparmor.service
+</code>
+returns:
+<code>
+● apparmor.service - AppArmor initialization
+   Loaded: loaded (/lib/systemd/system/apparmor.service; enabled; vendor preset: enabled)
+   Active: active (exited) since Sat 2019-11-23 10:23:26 GMT; 2 days ago
+     Docs: man:apparmor(7)
+           http://wiki.apparmor.net/
+  Process: 1181 ExecStart=/etc/init.d/apparmor start (code=exited, status=0/SUCCESS)
+ Main PID: 1181 (code=exited, status=0/SUCCESS)
+Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.
+</code>
+Also check the journal:
+<code bash>
+journalctl -u apparmor.service
+</code>
+returns:
+<code>
+-- Logs begin at Sun 2019-11-24 02:17:01 GMT, end at Mon 2019-11-25 21:05:42 GMT. --
+-- No entries --
+</code>
+----
+===== Disabling auto-start of services during boot =====
+If you want to disable auto-starting of services during boot you can use the following command:
+<code bash>
+sudo systemctl disable some-time-eater-service.service --now
+</code>
+However, you might want to see which other services needs the service in question. To check use the following command
+<code bash>
+systemctl list-dependencies some-service.service --reverse
+</code>
+Note: Replace **some-service.service** with actual service name.
+<WRAP important>
+**WARNING:**  Disabling a service doesn't make a service non-startable.  If you reboot, you could notice the service (daemon) is still running.  That’s because other dependencies may launch it, even if it’s disabled.
+Try to see what those may be:
+<code bash>
+systemd-analyze blame | grep some-service
+</code>
+If you want to completely disable it, read the next section.
+</WRAP>
+----
+===== Disabling services completely =====
+If you want to completely disable a service so that it can't be started, you should use mask instead of disable. Like this
+<code bash>
+sudo systemctl mask <SERVICE-NAME>
+</code>
+Replace the <SERVICE-NAME> with actual name of a service.
+The difference between mask and disable is mask make a service completely disable, you can't start it.  You must unmask to start it with systemd (you can still start with service).  But disable simply disables auto-start of a service, you can start it later.
+For example, after masking the some-service service, if you tried start it with systemctl the following message is shown
+Failed to start some-service.service: Unit some-service.service is masked.
+----
+===== Re-enable a service =====
+If you want to re-enable a service:
+<code bash>
+sudo systemctl unmask <SERVICE-NAME>
+sudo systemctl enable <SERVICE-NAME>
+</code>