Some solutions
Way 1. Add more cpus.(ABANDONED)
Way 2. Add a SSD as “boot cache”
Way 3. Sort the boot process

POC:
Way 2:
Sometimes we need cache the boot section of the OS into a SSD, since no SSD on hand, let’s try to use a block device made in /dev/shm

Way 3:
Considering that the parallelization of the “boot action”, we have to predict the action in the near future

Experiment:
Using BCACHE now…or flashcache