[OE-core] Results for xz compression with different -T and and -e

[Koen Kooi]

Op 12 jul. 2012, om 17:51 heeft Andrei Gherzan het volgende geschreven:

> On Thu, Jul 12, 2012 at 6:40 PM, Koen Kooi <koen at dominion.thruhere.net> wrote:
> 
> 
> Op 12 jul. 2012 om 17:29 heeft Andrei Gherzan <andrei at gherzan.ro> het volgende geschreven:
> 
> > Hello,
> >
> > Koen suggested to add -T to xz commands. We have this option implemented in our current version .1alpha.
> >
> > -T threads, --threads=threads
> >               Specify the number of worker threads to use.  Setting threads to
> >               a special value 0 makes xz use as many threads as there are  CPU
> >               cores  on  the system.  The actual number of threads can be less
> >               than threads if the input file is not big enough  for  threading
> >               with  the  given  settings or if using more threads would exceed
> >               the memory usage limit.
> >
> > -------------------
> >
> > Memory: 7.8 GiB
> > Processor:: Intel® Core™ i5-2540M CPU @ 2.60GHz × 4
> >
> > File to compress: 1.9G
> >
> > xz -f -k -e -9 --check=crc32 (current configuration)
> > Memory: 673Mb
> > real    6m37.170s
> > user    6m35.389s
> > sys     0m0.884s
> > Compressed file size: 3.4Mb
> >
> > xz -f -k -e -9 -T 4 --check=crc32
> > Memory: Cannot allocate memory
> >
> > xz -f -k -e -8 -T 4 --check=crc32
> > Memory: 1.8G
> > real    3m24.462s
> > user    12m8.502s
> > sys     0m2.180s
> > Compressed file size: 3.4Mb
> >
> > xz -f -k -T 4 --check=crc32 (-e defaults to -6)
> > Memory: 471Mb
> > real    1m9.265s
> > user    4m8.972s
> > sys     0m0.944s
> > Compressed file size: 3.4Mb
> >
> > So my conclusion would be to use the default -e -6 with -T 4.
> 
> Out of curiousity, what does -T0 give you?
> 
>  
> Exactly the same as -T 0. 

I don't see that in the results above :)