[systemd-devel] Exploring Minimal Systemd in Initramfs for Faster Boot

[Lennart Poettering]

On Mo, 23.09.24 09:33, Dharma.B at microchip.com (Dharma.B at microchip.com) wrote:

> Hi Team,
>
> I'm exploring the possibility of splitting the systemd binary to
> optimize boot time before and after switching to the root
> filesystem.

"the systemd binary"? There are a lot more than one...

> I’m aware that the systemd binary is quite large and may not fit in the
> initramfs, but is it feasible to have a minimal version of systemd that
> can invoke essential services and continue tracking them after
> transitioning to the main root filesystem?

Is it that large? Here on x86-64 it's 108K. libsystemd-core adds 2.3M,
libsystemd-shared adds 4.2M, and that's it. Not sure what good it
would do to "split" 108K? Why?

> This approach is aimed at speeding up the boot process. I’m unsure if
> this is possible, which is why I’m seeking guidance from the systemd
> mailing list.

The size of the systemd binary is unlikely to have much effect on boot
times. The question is what precisely you want to speed up? If you
want some specific service to finish starting up quickly then there
are ways for that. If you want the whole system to boot faster, then
you should figure out whre the bottleneck currently is.

Lennart

--
Lennart Poettering, Berlin