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

[Koen Kooi]

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?

regards,

koen


> 
> @g