"The tool consists of two pieces: the logging daemon bootchartd and a command-line utility that converts the log file into human-readable output chart. If you compiled the package from source, you will need to append the argument init=/sbin/bootchartd to your kernel command line in /boot/grub/menu.1st in order to make the kernel start the logging daemon in place of the normal /sbin/init initialization script. The logging daemon in turn calls /sbin/init itself, so no other part of the boot process requires alteration.
"Once running, bootchartd logs the start times and process states of every other running process, as well as CPU load, disk activity, and other statistics. As soon as it detects the KDE Display Manager or GNOME Display Manager greeter, it stops logging and bundles the result in /var/log. The Bootchart documentation says that the log is named /var/log/bootchart.tgz, but on Ubuntu the log is saved as a time-stamped file inside the directory /var/log/bootchart/ -- check your distro's documentation if neither location matches what you see."
