http://gizvillage.blogspot.com/2009/04/ ... se-of.html
Concurrent Booting: make full use of your dual-core, multithreaded or hyperthreaded processors in Ubuntu
This is a great way to make full use of your multi-core processors during boot time. I have an Intel core 2 duo processor and I have seen a notable change in boot time. Here's the how-to:
1. Enter the following command in a terminal window:
sudo gedit /etc/init.d/rc
Now look for CONCURRENCY=none and change it to CONCURRENCY=shell
2. But doing this might have some problems due to the dbus, hal and gdm race condition. For the multi-core processors to work properly, dbus should start first, hal the second and then gdm. This is not a problem in Hardy, Intrepid or Jaunty. For earlier versions, navigate to /etc/rc2.d/ folder by doing:
cd /etc/rc2.d/
Now do ls to list the files. Look for dbus, hal and gdm files. Mine has
s12dbus
s24hal
s30gdm
This means that dbus starts first, then the hal and then gdm. I you have something like this you don't have a problem. But if you have something similar to
s12dbus
s13gdm
s24hal
you need to do the following to fix this issue:
mv s24hal s13hal
mv s13gdm s14gdm
This will reorder the start processes and now CONCURRENCY=shell option can be used. For more information about the dbus, hal and gdm race condition, see this page. Please write in the comments if you have any questions.