Booting Linux in 5 seconds

At the Linux Plumbers Conference, Arjan van de Ven, Linux developer at Intel and author of PowerTOP, and Auke Kok, another Linux developer at Intel's Open Source Technology Center, demonstrated a Linux system booting in five seconds. The hardware was an Asus EEE PC, which has solid-state storage, and the two developers beat the five second mark with two software loads: one modified Fedora and one modified Moblin. They had to hold up the EEE PC for the audience, since the time required to finish booting was less than the time needed for the projector to sync.

How did they do it? Arjan said it starts with the right attitude. "It's not about booting faster, it's about booting in 5 seconds." Instead of saving a second here and there, set a time budget for the whole system, and make each step of the boot finish in its allotted time. And no cheating. "Done booting means CPU and disk idle," Arjan said. No fair putting up the desktop while still starting services behind the scenes. (An audience member pointed out that Microsoft does this.) The "done booting" time did not include bringing up the network, but did include starting NetworkManager. A system with a conventional hard disk will have to take longer to start up: Arjan said he has run the same load on a ThinkPad and achieved a 10-second boot time.

How they did it?