[Zlib-devel] pigz 2.1.4 available

[Mark Adler]

On Nov 10, 2008, at 8:36 PM, Nguyen Vu Hung wrote:
> Does it support Pentium 4 hyper threading?
> I've compared pigz with standard gzip and found no speedup.
>
> [vuhung at aoclife src]$ time gzip jdk-6u10-linux-i586.rpm
>
> real    0m7.220s
> user    0m4.851s
> sys     0m0.379s
> [vuhung at aoclife src]$ time pigz jdk-6u10-linux-i586.rpm
>
> real    0m7.726s
> user    0m12.227s
> sys     0m0.598s


Nguyen,

Since for pigz the user+sys time is greater than the real time, it  
appears that in fact the hyper-threading was being used.  It looks  
like you're getting about a 60% speedup from the hyperthreading.  To  
see how threading and not threading compare in a controlled manner,  
use pigz and pigz -p 1.

Looking at the user+sys time, gzip on your machine is very fast  
compared to pigz.  On my machine, pigz is only a little slower than  
gzip on a single processor.  I wonder if your gzip was compiled with  
assembler code for longest match, or if the zlib library was not  
optimized.  Or maybe the default compression level in your gzip was  
altered.

Mark