[arch-general] On-boot delay due to timer units

[Leonid Isaev]

Hi,

Since anacron jobs were replaced with timers, I am seeing a noticeable delay
before agetty prompt appears on machines which were unused for some time (due
to update/man-db timers starting up simultaneously).

TLDR: Anacron inserts a random delay between boot and running the jobs, so is
it possible to simulate this behavior by including e.g. "OnBootSec=..." in the
timers at next update? Or is this option incompatible with OnCalendar?

Here is the (edited) "statistics" obtained by grepping /var/log/daemon.log.
The disk is actually an Intel X-25 (sata-2) SSD.

--- No timers are active (baseline) ---
Apr  6: 5.983s (kernel) + 1.947s (userspace) = 7.930s.
Apr  6: 5.815s (kernel) + 2.494s (userspace) = 8.310s.
Apr  6: 5.692s (kernel) + 1.612s (userspace) = 7.304s.
Apr  7: 5.874s (kernel) + 2.561s (userspace) = 8.436s.
Apr  9: 5.704s (kernel) + 3.001s (userspace) = 8.706s.
Apr 10: 5.612s (kernel) + 2.494s (userspace) = 8.106s.
Apr 11: 5.618s (kernel) + 2.908s (userspace) = 8.526s.
Apr 12: 5.671s (kernel) + 3.345s (userspace) = 9.016s.

--- Timers first run ---
Apr 14: 5.464s (kernel) + 46.883s (userspace) = 52.348s.

--- Startup with timers ---
Apr 15: 5.715s (kernel) + 2.878s (userspace) = 8.593s.
Apr 16: Not powered on
Apr 17: 6.414s (kernel) + 7.785s (userspace) = 14.200s.
$ systemd-analyze blame | head
          6.724s man-db.service
          1.935s updatedb.service
           926ms root-ssh-key-init at 0x14d33aba.service
           507ms lxc at appserver\x2dx86_64.service
           427ms rfkill-unblock at wlan.service
           381ms systemd-networkd.service
           340ms wlan-powersave at wls1.service
           289ms syslog-ng.service
           235ms volatile-mail.service
           225ms iptables.service

Thanks,
L.

-- 
Leonid Isaev
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