dmesg 的输出：
[ 18.062831] wlp1s0: associated
[ 18.516902] IPv6: ADDRCONF(NETDEV_CHANGE): wlp1s0: link becomes ready
[ 18.844430] vboxdrv: loading out-of-tree module taints kernel.
[ 18.862837] vboxdrv: Found 8 processor cores
[ 18.880547] vboxdrv: TSC mode is Invariant, tentative frequency 1800001178 Hz
[ 18.880549] vboxdrv: Successfully loaded version 5.2.18_Ubuntu (interface 0x00290001)
[ 18.903066] VBoxNetFlt: Successfully started.
[ 18.925115] VBoxNetAdp: Successfully started.
[ 18.959469] VBoxPciLinuxInit
[ 18.975413] vboxpci: IOMMU not found (not registered)
[ 72.120167] Bluetooth: RFCOMM TTY layer initialized
[ 72.120177] Bluetooth: RFCOMM socket layer initialized
[ 72.120183] Bluetooth: RFCOMM ver 1.11
[ 74.132007] rfkill: input handler disabled
“蓝牙：RFCOMM TTY 层已初始化”花费了很多时间。
删除 virtualbox 后 dmesg 的输出：
[ 13.302018] IPv6: ADDRCONF(NETDEV_UP): wlp1s0: link is not ready
[ 13.395355] pcieport 0000:00:1d.0: AER: Corrected error received: 0000:00:1d.0
[ 13.395360] pcieport 0000:00:1d.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[ 13.395363] pcieport 0000:00:1d.0: device [8086:9d18] error status/mask=00000001/00002000
[ 13.395365] pcieport 0000:00:1d.0: [ 0] Receiver Error (First)
[ 13.411632] IPv6: ADDRCONF(NETDEV_UP): wlp1s0: link is not ready
[ 13.852753] IPv6: ADDRCONF(NETDEV_UP): wlp1s0: link is not ready
[ 17.499926] wlp1s0: authenticate with e4:6f:13:4f:4f:c0
[ 17.500332] pcieport 0000:00:1d.0: AER: Corrected error received: 0000:00:1d.0
[ 17.500340] pcieport 0000:00:1d.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[ 17.500344] pcieport 0000:00:1d.0: device [8086:9d18] error status/mask=00000001/00002000
[ 17.500347] pcieport 0000:00:1d.0: [ 0] Receiver Error (First)
[ 17.506088] wlp1s0: send auth to e4:6f:13:4f:4f:c0 (try 1/3)
[ 17.508958] wlp1s0: authenticated
[ 17.512158] wlp1s0: associate with e4:6f:13:4f:4f:c0 (try 1/3)
[ 17.516486] wlp1s0: RX AssocResp from e4:6f:13:4f:4f:c0 (capab=0x411 status=0 aid=1)
[ 17.518462] wlp1s0: associated
[ 17.612677] IPv6: ADDRCONF(NETDEV_CHANGE): wlp1s0: link becomes ready
[ 41.905950] Bluetooth: RFCOMM TTY layer initialized
[ 41.905961] Bluetooth: RFCOMM socket layer initialized
[ 41.905967] Bluetooth: RFCOMM ver 1.11
[ 43.554072] rfkill: input handler disabled
Systemd 分析：
Startup finished in 3.461s (kernel) + 22.792s (userspace) = 26.253s
graphical.target reached after 22.754s in userspace
Systemd-分析责任：
13.937s plymouth-quit-wait.service
7.473s [email protected]
6.502s NetworkManager-wait-online.service
5.480s fwupd.service
5.170s bolt.service
4.933s mysql.service
3.663s networkd-dispatcher.service
3.618s ModemManager.service
3.532s systemd-journal-flush.service
3.092s udisks2.service
2.637s dev-sda2.device
2.361s motd-news.service
2.348s accounts-daemon.service
2.310s apparmor.service
2.123s plymouth-read-write.service
1.849s gpu-manager.service
1.823s networking.service
1.774s avahi-daemon.service
1.732s bluetooth.service
1.727s grub-common.service
1.710s rsyslog.service
1.682s apport.service
1.643s wpa_supplicant.service
Acer Swift 3 笔记本电脑的
wifi 和蓝牙适配器是英特尔无线 7265。驱动程序 iwlwifi。256GB Micron 1100 SATA3 M.2 SSD。