Ubuntu 内核启动速度非常慢 - 时间在“raid6: sse2x1 gen() 858 MB/s”处跳过

Question

内核启动期间有一次跳过：

Jul 19 14:07:02 deetabokkusu kernel: [    2.874776] hub 1-1.4:1.0: USB hub found
Jul 19 14:07:02 deetabokkusu kernel: [    2.877993] hub 1-1.4:1.0: 4 ports detected
Jul 19 14:07:02 deetabokkusu kernel: [   94.080339] raid6: sse2x1   gen()   858 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.128306] raid6: sse2x1   xor()  2371 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.176324] raid6: sse2x2   gen()  1730 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.224328] raid6: sse2x2   xor()  2816 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.272285] raid6: sse2x4   gen()  2430 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.320302] raid6: sse2x4   xor()  2333 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.323121] raid6: using algorithm sse2x4 gen() 2430 MB/s
Jul 19 14:07:02 deetabokkusu kernel: [   94.325949] raid6: .... xor() 2333 MB/s, rmw enabled
Jul 19 14:07:02 deetabokkusu kernel: [   94.328762] raid6: using ssse3x2 recovery algorithm
Jul 19 14:07:02 deetabokkusu kernel: [   94.335698] xor: measuring software checksum speed
Jul 19 14:07:02 deetabokkusu kernel: [   94.376549]    prefetch64-sse:  7668.000 MB/sec
Jul 19 14:07:02 deetabokkusu kernel: [   94.416564]    generic_sse:  6661.000 MB/sec
Jul 19 14:07:02 deetabokkusu kernel: [   94.419385] xor: using function: prefetch64-sse (7668.000 MB/sec)
Jul 19 14:07:02 deetabokkusu kernel: [   94.426733] async_tx: api initialized (async)
Jul 19 14:07:02 deetabokkusu kernel: [   94.555496] Btrfs loaded, crc32c=crc32c-intel

systemd-analyze返回：

Startup finished in 1min 34.896s (kernel) + 38.914s (userspace) = 2min 13.810s graphical.target reached after 5.169s in userspace

systemd-analyze blame返回：

25.913s apt-daily.service 9.181s apt-daily-upgrade.service 2.131s dev-sda2.device 1.325s snapd.service 729ms media-duraibu1.mount 717ms networkd-dispatcher.service

我不是系统上运行 RAID。为了使内核启动更快，我需要更改什么？

编辑： 我感兴趣的是内核启动时间1 min 34.896s。我知道如何通过这些信息改善 38.914s 的用户空间启动时间systemd-analyze blame给我的信息改善 38.914s 的用户空间启动时间。

编辑 2： 使用另外两个 LTS 内核（v4.19.59 和 v4.14.133）启动并没有改变问题