[gentoo-user] Speed up with pbzip2 or not!?

[Justin <justin@j-schmitz.net>]

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Hey guys!

Yesterday I found this article
http://gentoo-wiki.com/HOWTO_Speed_up_decompression_with_pbzip2 and was
very happy, because I'm an owner of an Q6600.

So I tried to reproduce the benchmark from the wiki article but got that
bad results:

test # time *bzip2* -d -kf linux-2.6.23.tar.bz2

real    0m11.672s
user    0m11.306s
sys     0m0.367s


test # time *pbzip2* -d -p4 -kf linux-2.6.23.tar.bz2

real    0m25.554s
user    0m24.862s
sys     0m0.683s

So the parallel version took more than the double time!

To test whether this is a problem of my Pc I tested this on an Dual Core
with the same result.

An test with 7z was much better:


 test # time *7za* x -y linux-2.6.23.tar.bz2

real    0m4.642s
user    0m8.379s
sys     0m0.327s


All tests where done in a tmpfs off 1GB on 2GB RAM.


So my questions is what did I do wrong?

I also tested it with different CFLAGS, but my CFLAGS are basically very
conservative. (-O2 -march=prescott -pipe -fomit-frame-pointer)

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