Jonathan Edwards wrote: > On Mar 18, 2008, at 8:53 AM, Moinak Ghosh wrote: > >>> Do you have any numbers around the compression ratios >>> achieved but p7zip's implementation of gzip? >>> >> From past experience it will probably be around 2% better which >> will mean around 20MB savings after compression. >> >> In addition compressing the archive file using 7za(LZMA) will >> reduce it's size to 1/3rd of the current 40MB. >> > > here's a quick test i ran on the X.cpio install file from the last > SXDE(01/08) install disc > > . tests were run on mac os x - core 2 duo 2.33MHz - but am guessing > similar results on solaris > . [note: it appears that 7za and 7za bzip run multithreaded .. the > others don't ..] > > Original file: > -rw-r--r-- 1 root wheel 173M Mar 18 22:52 /var/tmp/test/X.cpio > > tool tcomp tdec size ratio > ---- ------ ------ ---- ----- > 7za 92.154 14.453 65M 2.66x > 7za-gz 43.454 6.760 85M 2.03x > 7za-bz2 40.615 8.320 83M 2.08x > gzip 19.280 6.660 88M 1.97x > gzip-9 45.475 6.435 88M 1.97x > bzip2 47.152 17.623 83M 2.08x > bzip2-9 47.472 17.736 83M 2.08x > rzip 59.153 28.728 76M 2.28x > rzip-9 75.279 26.356 76M 2.28x >
Interesting. BTW if I am not wrong, that X.cpio is mostly binaries whereas the archive.bz2 in DP is mostly text, so the ratios will vary. LZMA compression ratio is enormously improved with the parameter -mx=7. That parameter however increases compression time a lot and gobbles CPU. Decompression time is not affected though. Regards, Moinak.
