"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."