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.
@g
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