"C. Bergstr?m" wrote:

More details can be found here [1], but wanted to share some quick
numbers..

1.3M /usr/portage/packages/app-editors/vim-7.2.021.oxe
1.5M /usr/portage/packages/app-editors/vim-7.2.021.tbz2
Why is the *.oxe file smaller?
time xar -xf /usr/portage/packages/app-editors/vim-7.2.021.oxe
0.15u 0.01s 0:00.18 88.8%
Why is this extract faster?
time gtar -xf /usr/portage/packages/app-editors/vim-7.2.021.tbz2
0.24u 0.02s 0:00.26 100.0%

# Someone correct me if I'm doing this wrong
time /usr/bin/star -x -bz <
/usr/portage/packages/app-editors/vim-7.2.021.tbz2
0.24u 0.03s 0:00.35 77.1%
star should be the fastest in case you have similar constraints.....

star -xp -time < ../cdrtools-2.01.01.tar.bz2 -no-fsync
star: WARNING: Archive is 'bzip2' compressed, trying to use the -bz option.
star: 1021 blocks + 9728 bytes (total of 10464768 bytes = 10219.50k).
star: Total time 0.508sec (20076 kBytes/sec)
0.518r 0.480u 0.140s 124% 0M 0+0k 0st 0+0io 0pf+0w

gtar xjf - < ../cdrtools-2.01.01.tar.bz2
0.723r 0.490u 0.130s 88% 0M 0+0k 0st 0+0io 0pf+0w

Star defaults to a mode that grants you that everything could be unpacked
correctly to disk in case that the final star exit code is 0.
Other tar implementaions do not support this, so I swichted the secure
more off in the example above.

I ran it more than once and overall it seemed pretty consistent.. So
what exactly is under the hood
.tbz2 == bzip2 compressed data, block size = 900k + xpak tagged on
after EOF so that metadata can be easily extracted..
.oxe == xar archive - version 1 + xz (lzma2) compressed and using xar's
built-in toc to store metadata (gzip)
What compression is lzma2 and which program supports it?

J?rg

--
EMail:joerg@schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin
js@cs.tu-berlin.de (uni)
joerg.schilling@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/private/ ftp://ftp.berlios.de/pub/schily

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grouposunix-dev @
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postedJan 20, '09 at 10:55a
activeJan 20, '09 at 1:16p
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