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Booting Debian in 14 Seconds

Nov 12, 2008, 17:04 (0 Talkback[s])

"Instrumenting the boot process

"Your first step should be to measure how the time is currently being spent while your machine boots. Then optimise the slow bits, and don't worry about the bits that are already fast.

"A couple of tools are available for measuring the time taken during boot and visualising the results. I suggest that you install these tools first and save their results somewhere safe: I have not done so, and so I can no longer show you how slowly my machine booted before I started fixing it, which is a shame The total time was, IIRC, 33 seconds from the end of Grub to the xdm login dialog being visible; I've knocked 19 seconds off that.

"bootchart is available as a Debian package. Install it and boot with "init=/sbin/bootchartd" added to the kernel command line. (In Grub, select the kernel using the cursor keys, press e, select the line with the kernel command line, press e, edit, press return, and then press b.) Then run the bootchart utility which reads the log written during boot and creates an SVG graph. You can view the resulting file using most web browsers, or you can try "see" which will probably launch inkscape.

"The bootchart will show you which processes took the most time, and you can also see how much time was spent waiting for I/O and how much time was CPU-limited. If the results don't seem to make much sense, try running bootchart with its -n option; this makes the results more verbose."

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