XZ embedded bug unpacking linux-3.8.tar.xz

[Antonio Diaz Diaz]

Michael Tokarev wrote:
> So, I become curious how lzip behaves.  And I immediately gave it a very quick try.

I guess your try was indeed too quick. :-)

You didn't try lzip but plzip, which is beta software. And of course, 
parallel versions of lzip or xz compress less than standard versions 
because they split data in blocks before compressing it.

But even so there is someting wrong with your test. Maybe your C++ 
compiler produces slower executables than the C compiler, or you used an 
old version of plzip or lzlib... I have just retried to compress 
gcc-4.7.2.tar (just in case) and in my single-processor machine, plzip 
(using the default compression level) is faster(6:16) than both 
lzip(6:37) and xz(7:32), just as expected.

Why is this expected? Because both lzip and plzip use a default value 
for --match-length smaller than the equivalent option in xz (36 vs 64), 
and plzip sees a smaller effective dictionary size because it splits the 
input data in blocks.

There is no such thing as a free lunch. :-)


Regards,
Antonio.