[systemd-devel] Question: systemd-resolved.service delayed almost 90s start after systemd-sysctl.service

[Alien Kong]

Hello,

I'm seeing an unexpected 90s delay between systemd-sysctl.service and
systemd-resolved.service
in our boot sequence (systemd 255.4-1ubuntu8.4, custom embedded board).

systemd-analyze critical-chain shows:
multi-user.target @1min 54.340s
└─user_medium_priority.service @1min 32.653s +21.686s
  └─basic.target @1min 32.617s
    └─sockets.target @1min 32.615s
      └─ssh.socket @1min 32.614s
        └─sysinit.target @1min 32.580s
          └─systemd-resolved.service @1min 32.185s +394ms
            └─systemd-sysctl.service @2.726s +89ms
              └─systemd-modules-load.service @1.932s +577ms
                └─systemd-journald.socket @1.911s
                  └─-.mount @599ms
                    └─-.slice @598ms

We have verified no explicit dependency holding this back.
>From the information of systemd-analyze blame, the startup time of each
service is normal.
21.686s user_medium_priority.service
 2.537s nv_duv3.service
 1.996s dev-vblkdev30.device
 1.993s dev-vblkdev0.device
 1.818s dev-vblkdev2.device
 1.766s dev-vblkdev4.device
 1.762s dev-vblkdev5.device
 1.670s dev-vblkdev3.device
  794ms dev-vblkdev6.device
  792ms dev-vblkdev15.device
  785ms e2scrub_reap.service
  730ms systemd-logind.service
  711ms dev-vblkdev13.device
  703ms dev-vblkdev8.device
  667ms dev-vblkdev14.device
  657ms dev-vblkdev7.device
  635ms dev-vblkdev9.device
  577ms systemd-modules-load.service
  550ms systemd-networkd.service
  394ms systemd-resolved.service
  367ms ap-com-daemon.service
  286ms systemd-udev-trigger.service
  253ms user at 1000.service
  248ms systemd-tmpfiles-setup.service
  227ms ssh.service
  124ms systemd-tmpfiles-clean.service
  119ms systemd-tmpfiles-setup-dev.service
  116ms systemd-user-sessions.service
  114ms systemd-tmpfiles-setup-dev-early.service
...

Any ideas for further investigation of this situation? Thanks~
Any insight would be appreciated.

Best regards,
Alien Kong
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