Joerg Schilling wrote:
"C. Bergstr?m" wrote:

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

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?
Not always smaller, but it's a result of xz vs bzip2 compression..
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?
xz is faster at decompressing than bzip2 and a smaller file?
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 <
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.

time /usr/bin/star -xp -bz <
/usr/portage/packages/app-editors/vim-7.2.021.tbz2 -no-fsync
/usr/bin/star: WARNING: skipping leading '/' on filenames.
/usr/bin/star: 416 blocks + 0 bytes (total of 4259840 bytes = 4160.00k).
0.24u 0.02s 0:00.27 96.2%

/usr/bin/star -xp -bz -time <
/usr/portage/packages/app-editors/vim-7.2.021.tbz2 -no-fsync
/usr/bin/star: WARNING: skipping leading '/' on filenames.
/usr/bin/star: 416 blocks + 0 bytes (total of 4259840 bytes = 4160.00k).
/usr/bin/star: Total time 0.256sec (16186 kBytes/sec)

J?rg.. what's the short-cut way to have star compress "." and pipe it
through xz so it's an apple vs apple comparison on the compression being

Also does star have some functionality like..

xar -cf filepath --compression=xz -n package_meta.xml -s foo.xml
xar --dump-toc=foo.xml -f /usr/portage/packages/app-editors/vim-7.2.021.oxe
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?

xz (lzma2) is beta work from Lasse Collin & Igor Pavlov.


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



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