> They started out with around a three second kernel boot time but cut it down to just 300 ms. Among the optimizations carried out to really speed-up their boot time were ensuring more asynchronous driver probing, only initializing a small amount of RAM at start and then after booted hot-plug the rest of it in parallel via systemd, optimized root file-system mounting, disabling unnecessary kernel modules, and similar approaches. Moving forward they are still looking at optimizations for the boot process around in-kernel deferred memory initialization, SMP initialization changes, ACPI tweaking, and user-space/systemd optimizations.
