需要几分钟才能进入登录屏幕，比同一台机器上的 Windows 7 慢得多。这是一台 T3500 Xeon 机器，配有 24 GB RAM 和 NVIDIA GeForce GTX 760。整个过程中有大量高清活动。
这是一个相当新的安装（几个月前），尽管我在安装过程中确实保留了我的主目录。我不记得它在安装后启动速度曾像我想象的那么快，但也许随着时间的推移它也变得更糟了……
登录后，一切都响应迅速且感觉正常。
下面是 dmesg 的相关部分（4 秒标记之前有很多内容可能不相关）。
我注意到下面的时间上有一些“间隙”，但我不确定如何解释它们。我猜这些消息是在每个操作完成后发布的，因此造成间隙的罪魁祸首是间隙之后的消息。但是间隙中间出现的“审计”消息怎么办？
[ 4.388089] xor: measuring software checksum speed
[ 4.388686] prefetch64-sse : 17386 MB/sec
[ 4.389336] generic_sse : 15151 MB/sec
[ 4.389337] xor: using function: prefetch64-sse (17386 MB/sec)
[ 4.420250] Btrfs loaded, crc32c=crc32c-intel, zoned=yes
[ 5.112892] EXT4-fs (sda5): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
[ 5.232617] random: crng init done
[ 6.776820] systemd[1]: RTC configured in localtime, applying delta of -240 minutes to system time.
[ 7.124970] systemd[1]: Inserted module 'autofs4'
[ 7.373179] systemd[1]: systemd 245.4-4ubuntu3.15 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN2 -IDN +PCRE2 default-hierarchy=hybrid)
[ 7.392480] systemd[1]: Detected architecture x86-64.
[ 7.426090] systemd[1]: Set hostname to <Precision-Workstation-T3500>.
[ 10.182570] systemd[1]: Created slice system-modprobe.slice.
[ 10.182862] systemd[1]: Created slice system-systemd\x2dfsck.slice.
[ 10.183106] systemd[1]: Created slice User and Session Slice.
[ 10.183168] systemd[1]: Started Forward Password Requests to Wall Directory Watch.
[ 10.183344] systemd[1]: Set up automount Arbitrary Executable File Formats File System Automount Point.
[ 10.183389] systemd[1]: Reached target User and Group Name Lookups.
[ 10.183405] systemd[1]: Reached target Remote File Systems.
[ 10.183416] systemd[1]: Reached target Slices.
[ 10.183430] systemd[1]: Reached target Swap.
[ 10.183505] systemd[1]: Listening on Device-mapper event daemon FIFOs.
[ 10.183602] systemd[1]: Listening on LVM2 poll daemon socket.
[ 10.183692] systemd[1]: Listening on Syslog Socket.
[ 10.183788] systemd[1]: Listening on fsck to fsckd communication Socket.
[ 10.183843] systemd[1]: Listening on initctl Compatibility Named Pipe.
[ 10.184032] systemd[1]: Listening on Journal Audit Socket.
[ 10.184121] systemd[1]: Listening on Journal Socket (/dev/log).
[ 10.184236] systemd[1]: Listening on Journal Socket.
[ 10.184469] systemd[1]: Listening on udev Control Socket.
[ 10.184555] systemd[1]: Listening on udev Kernel Socket.
[ 10.185492] systemd[1]: Mounting Huge Pages File System...
[ 10.186419] systemd[1]: Mounting POSIX Message Queue File System...
[ 10.187482] systemd[1]: Mounting Kernel Debug File System...
[ 10.188473] systemd[1]: Mounting Kernel Trace File System...
[ 10.190013] systemd[1]: Starting Journal Service...
[ 10.190917] systemd[1]: Starting Availability of block devices...
[ 10.258863] systemd[1]: Starting Set the console keyboard layout...
[ 10.259807] systemd[1]: Starting Create list of static device nodes for the current kernel...
[ 10.260767] systemd[1]: Starting Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling...
[ 10.260810] systemd[1]: Condition check resulted in Load Kernel Module drm being skipped.
[ 10.351656] systemd[1]: Condition check resulted in Set Up Additional Binary Formats being skipped.
[ 10.351719] systemd[1]: Condition check resulted in File System Check on Root Device being skipped.
[ 10.397206] systemd[1]: Starting Load Kernel Modules...
[ 10.398074] systemd[1]: Starting Remount Root and Kernel File Systems...
[ 10.399077] systemd[1]: Starting udev Coldplug all Devices...
[ 10.399969] systemd[1]: Starting Uncomplicated firewall...
[ 10.401590] systemd[1]: Mounted Huge Pages File System.
[ 10.401755] systemd[1]: Mounted POSIX Message Queue File System.
[ 10.401904] systemd[1]: Mounted Kernel Debug File System.
[ 10.402050] systemd[1]: Mounted Kernel Trace File System.
[ 10.402533] systemd[1]: Finished Availability of block devices.
[ 10.403086] systemd[1]: Finished Create list of static device nodes for the current kernel.
[ 10.441020] systemd[1]: Started Journal Service.
[ 10.633273] EXT4-fs (sda5): re-mounted. Opts: (null). Quota mode: none.
[ 10.719592] systemd-journald[324]: Received client request to flush runtime journal.
[ 11.147230] lp: driver loaded but no devices found
[ 11.197851] ppdev: user-space parallel port driver
[ 11.297121] parport_pc 00:02: reported by Plug and Play ACPI
[ 11.297183] parport0: PC-style at 0x378 (0x778), irq 7, using FIFO [PCSPP,TRISTATE,COMPAT,EPP,ECP]
[ 11.392747] lp0: using parport0 (interrupt-driven).
[ 11.991584] loop0: detected capacity change from 0 to 457024
[ 12.024804] loop1: detected capacity change from 0 to 226912
[ 15.056695] nvidia_uvm: module uses symbols from proprietary module nvidia, inheriting taint.
[ 15.060198] nvidia-uvm: Loaded the UVM driver, major device number 511.
[ 15.914047] EDAC MC0: Giving out device to module i7core_edac.c controller i7 core #0: DEV 0000:3f:03.0 (INTERRUPT)
[ 15.914071] EDAC PCI0: Giving out device to module i7core_edac controller EDAC PCI controller: DEV 0000:3f:03.0 (POLLED)
[ 15.914087] EDAC i7core: Driver loaded, 1 memory controller(s) found.
[ 16.122274] dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.4)
[ 16.207716] dell-smbios A80593CE-A997-11DA-B012-B622A1EF5492: WMI SMBIOS userspace interface not supported(0), try upgrading to a newer BIOS
[ 16.250825] input: Dell WMI hotkeys as /devices/platform/PNP0C14:00/wmi_bus/wmi_bus-PNP0C14:00/9DBB5994-A997-11DA-B012-B622A1EF5492/input/input14
[ 17.513791] kvm: VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL does not work properly. Using workaround
[ 18.802951] mc: Linux media interface: v0.10
[ 19.013917] usbcore: registered new interface driver snd-usb-audio
[ 19.244103] snd_hda_intel 0000:03:00.1: Disabling MSI
[ 19.244112] snd_hda_intel 0000:03:00.1: Handle vga_switcheroo audio client
[ 19.283402] input: HDA NVidia HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input15
[ 19.283456] input: HDA NVidia HDMI/DP,pcm=7 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input16
[ 19.283508] input: HDA NVidia HDMI/DP,pcm=8 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input17
[ 19.283602] input: HDA NVidia HDMI/DP,pcm=9 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input18
[ 19.283705] input: HDA NVidia HDMI/DP,pcm=10 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input19
[ 19.283754] input: HDA NVidia HDMI/DP,pcm=11 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input20
[ 19.283798] input: HDA NVidia HDMI/DP,pcm=12 as /devices/pci0000:00/0000:00:07.0/0000:03:00.1/sound/card2/input21
[ 19.806184] snd_hda_codec_analog hdaudioC0D0: autoconfig for AD1984A: line_outs=1 (0x12/0x0/0x0/0x0/0x0) type:line
[ 19.806194] snd_hda_codec_analog hdaudioC0D0: speaker_outs=1 (0x13/0x0/0x0/0x0/0x0)
[ 19.806198] snd_hda_codec_analog hdaudioC0D0: hp_outs=1 (0x11/0x0/0x0/0x0/0x0)
[ 19.806202] snd_hda_codec_analog hdaudioC0D0: mono: mono_out=0x0
[ 19.806204] snd_hda_codec_analog hdaudioC0D0: inputs:
[ 19.806207] snd_hda_codec_analog hdaudioC0D0: Mic=0x14
[ 19.806209] snd_hda_codec_analog hdaudioC0D0: Line=0x15
[ 19.823267] input: HDA Intel Mic as /devices/pci0000:00/0000:00:1b.0/sound/card0/input22
[ 19.823319] input: HDA Intel Line as /devices/pci0000:00/0000:00:1b.0/sound/card0/input23
[ 19.823366] input: HDA Intel Line Out as /devices/pci0000:00/0000:00:1b.0/sound/card0/input24
[ 19.823409] input: HDA Intel Front Headphone as /devices/pci0000:00/0000:00:1b.0/sound/card0/input25
[ 22.113084] EXT4-fs (sdb2): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
[ 22.687524] audit: type=1400 audit(1650979147.112:2): apparmor="STATUS" operation="profile_load" profile="unconfined" name="libreoffice-xpdfimport" pid=706 comm="apparmor_parser"
[ 22.687752] audit: type=1400 audit(1650979147.112:3): apparmor="STATUS" operation="profile_load" profile="unconfined" name="lsb_release" pid=705 comm="apparmor_parser"
[ 22.688712] audit: type=1400 audit(1650979147.116:4): apparmor="STATUS" operation="profile_load" profile="unconfined" name="libreoffice-oopslash" pid=703 comm="apparmor_parser"
[ 22.776323] audit: type=1400 audit(1650979147.200:5): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/snapd/snap-confine" pid=704 comm="apparmor_parser"
[ 22.776330] audit: type=1400 audit(1650979147.200:6): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/snapd/snap-confine//mount-namespace-capture-helper" pid=704 comm="apparmor_parser"
[ 22.852963] audit: type=1400 audit(1650979147.280:7): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/mysqld" pid=708 comm="apparmor_parser"
[ 22.939713] audit: type=1400 audit(1650979147.364:8): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=710 comm="apparmor_parser"
[ 22.939720] audit: type=1400 audit(1650979147.364:9): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/NetworkManager/nm-dhcp-helper" pid=710 comm="apparmor_parser"
[ 22.939723] audit: type=1400 audit(1650979147.364:10): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/connman/scripts/dhclient-script" pid=710 comm="apparmor_parser"
[ 22.939726] audit: type=1400 audit(1650979147.364:11): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/{,usr/}sbin/dhclient" pid=710 comm="apparmor_parser"
[ 33.796959] Bluetooth: Core ver 2.22
[ 33.796988] NET: Registered protocol family 31
[ 33.796990] Bluetooth: HCI device and connection manager initialized
[ 33.796993] Bluetooth: HCI socket layer initialized
[ 33.796995] Bluetooth: L2CAP socket layer initialized
[ 33.796998] Bluetooth: SCO socket layer initialized
[ 35.175252] kauditd_printk_skb: 26 callbacks suppressed
[ 35.175255] audit: type=1400 audit(1650979159.600:38): apparmor="DENIED" operation="capable" profile="/usr/sbin/cups-browsed" pid=894 comm="cups-browsed" capability=23 capname="sys_nice"
[ 43.187673] tg3 0000:05:00.0 enp5s0: Link is up at 1000 Mbps, full duplex
[ 43.187684] tg3 0000:05:00.0 enp5s0: Flow control is on for TX and on for RX
[ 43.187699] IPv6: ADDRCONF(NETDEV_CHANGE): enp5s0: link becomes ready
[ 53.490839] resource sanity check: requesting [mem 0x000c0000-0x000fffff], which spans more than 0000:03:00.0 [mem 0x000c0000-0x000dffff]
[ 53.490845] caller os_map_kernel_space+0x88/0xd0 [nvidia] mapping multiple BARs
[ 55.317481] nvidia-modeset: WARNING: GPU:0: Unable to read EDID for display device DVI-I-0
[ 82.279865] audit: type=1400 audit(1650979206.048:39): apparmor="DENIED" operation="capable" profile="/usr/sbin/cups-browsed" pid=1733 comm="cups-browsed" capability=23 capname="sys_nice"
[ 85.717509] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 85.717513] Bluetooth: BNEP filters: protocol multicast
[ 85.717517] Bluetooth: BNEP socket layer initialized
[ 100.693373] nvidia-modeset: WARNING: GPU:0: Unable to read EDID for display device DVI-I-0
[ 101.081318] nvidia-modeset: WARNING: GPU:0: Unable to read EDID for display device DVI-I-0
[ 101.105153] nvidia-modeset: WARNING: GPU:0: Unable to read EDID for display device DVI-I-0
[ 107.384620] audit: type=1400 audit(1650979231.156:40): apparmor="DENIED" operation="mknod" profile="/usr/bin/evince-thumbnailer" name="/home/jasonrohrer/.cache/thumbnails/normal/50fabd4e0e74c10430ce1c69e2c4464b.png" pid=2107 comm="evince-thumbnai" requested_mask="c" denied_mask="c" fsuid=1000 ouid=1000
[ 107.739468] audit: type=1400 audit(1650979231.508:41): apparmor="DENIED" operation="mknod" profile="/usr/bin/evince-thumbnailer" name="/home/jasonrohrer/.cache/thumbnails/normal/6d1229cfb0dd90a5343ac369a065843a.png" pid=2111 comm="evince-thumbnai" requested_mask="c" denied_mask="c" fsuid=1000 ouid=1000
[ 159.909731] SGI XFS with ACLs, security attributes, realtime, quota, no debug enabled
[ 159.967878] JFS: nTxBlock = 8192, nTxLock = 65536
[ 160.018782] ntfs: driver 2.1.32 [Flags: R/O MODULE].
[ 160.101345] QNX4 filesystem 0.2.3 registered.
我刚刚再次启动它，从我在 GRUB 屏幕上按下 ENTER 到进入登录屏幕并输入密码花了 85 秒。
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 8.787s
└─multi-user.target @1min 8.787s
└─mysql.service @24.716s +44.070s
└─network.target @24.713s
└─NetworkManager.service @17.814s +6.898s
└─dbus.service @17.811s
└─basic.target @17.650s
└─sockets.target @17.650s
└─snapd.socket @17.649s +817us
└─sysinit.target @17.578s
└─systemd-timesyncd.service @17.299s +278ms
└─systemd-tmpfiles-setup.service @17.143s +118ms
└─systemd-journal-flush.service @4.425s +12.716s
└─systemd-remount-fs.service @4.074s +263ms
└─systemd-journald.socket @3.860s
└─-.mount @3.857s
└─system.slice @3.857s
└─-.slice @3.857s