Re: emulate an end-of-media

Tim Kientzle wrote:

Why compress? It's ancient technology and will be vastly outperformed


Yes, gzip or bzip2 compress better, but they also:
* Are a lot slower.
* Use a lot more data memory.
* Require a lot more code.

I don't understand what "a lot more code" has to do with anything. gzip/zlib is part of base and portable.

In my quick tests on some real dump files, *if* you are able to specify the compression quality, then gzip -1 is both faster and better compressing than compress. If I'm reading time correctly, then gzip at any compression level used less memory than compress. bzip2 uses more memory but -9 always uses roughly the same amount of memory: ~9Mb.

180672 -r--r----- 1 root alex - 184893440 Feb 26 09:08 cartman-root.dump.0

131 {root @ ren} # time compress cartman-root.dump.0
7.948u 0.264s 0:08.93 91.8% 15+744k 0+725io 0pf+0w
92896 -r--r----- 1 root alex - 95051115 Feb 26 09:08 cartman-root.dump.0.Z

134 {root @ ren} # time gzip -1 cartman-root.dump.0
6.543u 0.288s 0:06.93 98.4% 56+585k 1+549io 2pf+0w
70368 -r--r----- 1 root alex - 71979780 Feb 26 09:08 cartman-root.dump.0.gz

137 {root @ ren} # time gzip -9 cartman-root.dump.0
44.588u 0.304s 0:46.53 96.4% 56+584k 0+494io 0pf+0w
63344 -r--r----- 1 root alex - 64800326 Feb 26 09:08 cartman-root.dump.0.gz

140 {root @ ren} # time bzip2 cartman-root.dump.0
51.327u 0.398s 0:53.44 96.7% 30+9638k 3+471io 3pf+0w
60384 -r--r----- 1 root alex - 61769750 Feb 26 09:08 cartman-root.dump.0.bz2

And for a largely text filesystem dump:

58352 -r--r----- 1 root alex - 59699200 Feb 26 09:13 cartman-var.dump.0

152 {root @ ren} # time compress cartman-var.dump.0
2.179u 0.102s 0:02.31 98.2% 15+737k 0+156io 1pf+0w
20000 -r--r----- 1 root alex - 20456769 Feb 26 09:13 cartman-var.dump.0.Z

155 {root @ ren} # time gzip -1 cartman-var.dump.0
1.441u 0.069s 0:01.53 98.0% 57+592k 0+116io 0pf+0w
14992 -r--r----- 1 root alex - 15328819 Feb 26 09:13 cartman-var.dump.0.gz

158 {root @ ren} # time gzip -9 cartman-var.dump.0
4.807u 0.062s 0:04.89 99.3% 56+583k 0+104io 0pf+0w
13424 -r--r----- 1 root alex - 13727598 Feb 26 09:13 cartman-var.dump.0.gz

161 {root @ ren} # time bzip2 cartman-var.dump.0
28.057u 0.132s 0:28.97 97.2% 30+9629k 0+91io 0pf+0w
11792 -r--r----- 1 root alex - 12052157 Feb 26 09:13 cartman-var.dump.0.bz2


--Alex

_______________________________________________
freebsd-hackers@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@xxxxxxxxxxx"

Relevant Pages