Speeding up live cd boot through optimizing file layout

[Krzysztof Lichota]

Jun Kobayashi napisał(a):
> Hello,
> 
> Krzysztof Lichota wrote:
>> I have taken a shot at optimizing boot speed of Kubuntu live CD by
>> changing layout of files on CD (no changes to live CD contents).
> 
> I found 2 candidates of improvement for optimizing boot speed of live CD.
> 
> 1. Adding files used in initrd.gz to rootfs.sort
> 
> With Krzysztof's instruction, the '/dev/.squash.log' dosen't include
> files used by scripts on initrd.gz. For instance, configuration scripts
> for xserver-xorg (e.g. /var/lib/dpkg/info/xserver-xorg.config) are
> kicked during boot up, but /dev/.squash.log dosen't include them.
> These files found in '/dev/.static/dev/.squash.log'.
> I merged these two .squash.log, generate my rootfs.sort, and make
> filesystem.squashfs with this sort file. This boots up 9 seconds faster
> with my PC.

Good point. Apparently after pivot_root it lands in different place. I
will have to merge these two files.

> 2. Changing priority value in rootfs.sort
> 
> According to the manual and changelog of squashfs, highest priority
> files are now placed at the start of the filesystem and default priority
> is 0.
> With Krzysztof's sort-files-by-first-access.py, priority value start with
> 10000 and going down. I think this makes files place at the start of the
> squashfs filesystem. So I changed priority values to -1, -2, -3 ... to
> place files at end of squashfs.
> This comes good in my case - boots up 7 seconds faster.

Yes, but I guess that further operations might be spoiled, because now
libraries are at the end of CD, while apps not run during tracing are at
the beginning of CD. You have to choose what you prefer, faster boot or
faster operation of these apps :)

> I'll happy if Krzysztof and others verify these improvements.

I will try to test it when I have some spare time.

Thanks for feedback :)

	Krzysztof Lichota


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