On Sun, 2008-01-27 at 10:58 +0100, Justin wrote:
> 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
> 

> So my questions is what did I do wrong?


Did you compress it with pbzip2 in the first place?

Pbzip2 can only speed up decompression of files created by pbzip2, as
well. Read the docs, dude ...

p7zip has got its own implementation of bzip2, which might be faster.