Re: [Lzip-bug] On Windows unpacking does not use all cores

[Antonio Diaz Diaz]

Hello Romano,

Romano wrote:
> Yesterday I compiled latest lzlib 1.9 and plzip 1.7 under cygwin(also
> latest, just installed yesterday) on Windows 7 and as a 64bit both. It
> compiled without any errors or warning and tool also work fine. During
> packing it is able to utilize all CPU cores to 100% so multithreading
> works. Same with testing using -t flag. Howerver, when I actually try to
> unpack with -d it never even peak above 50%. This despite -n option,
> even if I double the number to -n 8. On parallel, until now I always
> used FreeArc's internal 4x4:lzma which always fully utilized my cpu and
> it shows as during unpacking without io limitation it could reach
> ~200Mib/s.

I don't use Windows, so I can't test your executable. (BTW, please, 
don't spam the list with huge unsolicited files). The fact that plzip 
can use all cores while testing makes me suspect of some I/O 
problem/idiosyncrasy. See for example this thread on the MinGW list:
http://sourceforge.net/p/mingw/mailman/message/35749043/


> I am aware of blocks concept as well, tool also did not utilized all CPU
> with smaller -B block and big enough file, and I know for sure its not
> my HDD limiting it because first it is quicker than output and FreeArc
> can still utilize its max, but also because it does not utilize full CPU
> even if using stdin/stdout.

Even if decompressing from a regular file to /dev/null ?


> I hope this help you and thanks for a great tool you did.

You are welcome.


> (PS: Also, I dont know if this is a bug in plzip, but if I compress
> under Freearc and click "cancel", first 3 threads eventually cancel as
> they should but last one remain with CPU at 25% forever - thus plzip
> never quit.)

Sorry, but I am not familiar with FreeArc. Do you know if it is plzip or 
FreeArc the one stuck in the infinite loop? Plzip should exit as soon as 
its standard input is closed by FreeArc.


Best regards,
Antonio.