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--- boot:speed_up_boot [2019/11/25 21:44] – peter
+++ boot:speed_up_boot [2019/11/25 22:48] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== 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 doesn’t account for the time your graphical interface requires to boot up.
-To put it another way, this shows you how much time is required, from the moment the kernel is loaded until you are dropped to the Linux console.
-However, you can also see the time required by the graphical interface to initialize with this command:
-<code bash>
-systemd-analyze critical-chain
-</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>
-----
-===== 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>
-----
-===== Check the critical chain =====
-and now analyze each major process.  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-time-eater-service.service --reverse
-</code>
-Note: Replace some-time-eater-service.service with actual service name like postgresql@9.5-main.service.
-Note that, disabling auto-start doesn't make a service non-startable. The service can be started after boot when requirement arises. If you want to completely disable it, read the next section
-----
-===== 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 disable auto-start of a service, you can start it later.
-For example, After masking my postgresql@9.5-main.service service, when I wanted to start it with systemctl the following message is shown
-Failed to start postgresql@9.5-main.service: Unit postgresql@9.5-main.service is masked.