[Fedora-livecd-list] [PATCH] --turbo-liveinst improves livecd installer speed by about 20%

[Douglas McClendon]

Attached are a couple of rough alpha quality patches.

They implement what I have described rather verbosely on fedora-livecd-list and 
in bug 248082.

The short story is the fedora7 livecd installer works by copying a 4G ext3 image 
to the destination rootfs, and then resizing to maximal size.

The attached patches improve the speed of this step by 10-30% (for cdrom vs fast 
livecd-iso-to-disk'd usbflash install media respectively).

This is accomplished because the 4G image actually only holds 2G of data.  The 
patch to livecd-creator, when invoked with --turbo-liveinst, will create a small 
(25kb) binary delta file on the livecd.  The patch to anaconda, will detect the 
presence of the file, and if it is there, use it with devicemapper to create a 
2G ext3 image, which can naturally be copied to the destination volume more 
quickly.  (I.e. 2G of zeros don't get written to disk).

In addition to improving installation speed, this also results in rootfs volumes 
of 2.1G->3.9G being supported.

This patch is less than polished and elegant.  But I'm hoping it might make it 
into f8t1.  Please review, and give suggestions for improvements.  I'll plan on 
trying to clean it up in whatever ways seem best over the next couple of days.

These are patches against current livecd git and anaconda cvs snaps.  I think 
they will work (very limited testing so far), but mainly I post them to get 
eyeballs and brains looking at the code and the idea.  No doubt within 24-48 
hours I will post a more respectable looking patchset that I hope more people 
might be willing to test.

(note, the cleanupDeleted patch I just posted to livecd-tools is included here, 
as it lays the foundation for this...  as well as reclaiming lots (5-15+%) of 
wasted space on the livecd)

-dmc

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