Compression Time

Compression times

The times measured were from user seconds when running on a 2.4 GHz celeron. This measures only the user times of the tools so the actual times would be much longer (user times don't include the system calls) but I don't really care about measuring the speed of my hard disk so its more relevant. Also do note the lack of ace results as there are no Unix ace compressors.

/bin/*

7z	23.2
arj	5.51
jar	6.21
lha	14.26
rar	10.81
sit	11.45
tar.bz2	7.02
tar.gz	10.37
tar.lzo	20.69
tar.Z	2.51
zip	9.36
zoo	1.28

Here 7z shows its weakness. Not only in this test but across the board it consumes around two to three times the average time. tar.lzo also uses a lot of processor time despite its poor compression score.

Jpeg

7z	34.9
arj	3.67
jar	5.15
lha	11.26
rar	15.38
sit	30.7
tar.bz2	19.02
tar.gz	5.43
tar.lzo	16.35
tar.Z	4.99
zip	4.53
zoo	10.35

Sit compressor seems to have a spot of trouble with these jpegs. It spends a lot of time trying to compress the not very compressible.

Linux

7z	242.13
arj	30.75
jar	22.58
lha	77.02
rar	86.28
sit	111.47
tar.bz2	76.37
tar.gz	73.04
tar.lzo	159.21
tar.Z	31.3
zip	44.73
zoo	9.43

The kernel results are pretty average but due to its large size it can be used to show how much additional time is spent on system reading/writing files etc. In this case it was around 16 seconds in all compressors. This means that trying to drop below a few seconds compression time would result in very little performance improvement. That said most compressors do take considerably longer than 10 seconds.

Roms

7z	89.43
arj	16.61
jar	19.48
lha	68.33
rar	55.54
sit	68.63
tar.bz2	53.48
tar.gz	30.38
tar.lzo	63.8
tar.Z	12.88
zip	32.92
zoo	11.31

This is the final compression time graph but you can see the graph of all tests.