[systemd-devel] Reducing unmount/mount of partitions on soft-reboot

[Aditya Gupta]

Hello,

I tried systemd-soft-reboot on a RHEL system, and it's amazing in terms
of it's ability to do a userspace reboot, within fraction of time of a
full system reboot. For example, for a Power system taking around 50
seconds to do a normal reboot, it took around 4-5 seconds for a
systemd-soft-reboot.

I have a question on further optimisation. After soft-reboot, I notice
much of the time is taken up by .device and .mount services. This was my
observation based on 'systemd-analyze blame'. Please do let me know if
I am seeing the wrong numbers, or if there's a better way to know.

Is there some way to 'pass-through' these mounts ? That is, I might not
need to unmount and remount my boot/root paritions.

I tried finding this in available documentation, sorry if I missed it. I
did find this ability to 'pass-through' resources/file
descriptors/sockets to next boot, by modifying the service files, but
don't know how and if I can do a similar thing with mounts.

Thanks,
Aditya Gupta