LiveCD optimisations

Louis Simard louis.simard at
Fri May 21 00:35:55 UTC 2010

Greetings ubuntu-devel-discuss :)

I have a proposal for you, and I'll present it simply with the 5 W's.

-- WHAT? --

Optimise the PNG images and SVG files on the Ubuntu LiveCD.
Optimise the Ubuntu LiveCD by putting start-up files and programs near
the end of the CD.

-- WHY? --

Optimising the PNG images saves 5.5 MB on the filesystem.squashfs.
Optimising the SVG files saves an additional 7 MB. This is a total of
12.5 MB which could be used to pack more software or another language
pack or two onto the LiveCD.
Optimising the CD to put files at the end allows it to boot marginally
faster (about 10 seconds on my benchmarks), start applications faster,
and allows the CD drive on a user's computer to run quieter while
using his/her applications, as reading near the end (edge of the disc)
requires slower spinning.
These changes will give prospective users a better view of Ubuntu
right from the LiveCD. There might also be additional benefits to
having smaller PNG and SVG images, such as saving space on a user's
hard disk when installed. The uncompressed (pre-squashfs) savings for
the SVG images is 18 MB.

-- WHEN? --

Now! :) Just kidding. As soon as possible would be nice. Maybe even
for the next Ubuntu version, codename Maverick Meerkat!

-- WHO? --

Ubuntu developers. But don't go thinking that you'll do all the grunt
work of testing these optimisations for yourself! (See HOW? below)

-- HOW? --

Attached to this email is a bash script I've made to perform all of
these optimisations on any Canonical-supported Ubuntu 10.04
LiveCD image, almost automatically. (After optimisations are done, you
can check the state of the LiveCD in a bash shell from within it. The
rest is fully automatic.)

The real savings would come from optimising the PNG and SVG images
right in the packages themselves, not just the LiveCD. Given a
directory containing PNG and SVG images, the part of my script dealing
with OptiPNG and can automatically optimise these files. The
best candidate for such a Scouring would be ubuntu-docs, as it has
tons of PNG images. Most application packages have an SVG icon or two
as well.

Thanks for your time!
- Louis
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