On Fri, Nov 09, 2012 at 07:48:22PM +0100, Guillem Jover wrote: > There used to be a single global default level (9) for all compressors, > which got changed in 2010 to be backend specific, but only xz and lzma > were reduced to 6. I don't have any problem with changing gzip (to its > upstream default!) if as shown it's a vast improvement speed vs space. > I can certainly do that for dpkg 1.17.x, some more numbers would be > nice though, as in different types of data.tar, for example, but I > would not expect any surprises here, mostly just for reassurance.
Okay. I did some tests with various packages. From binary only to text only. Package | gzip -6 | gzip -9 | gzip | xz -1 --------------------------+----------+-----------------+--------- libc6 | 4339010 | 4321933 | 0.5% | 2938132 perl-modules | 3874170 | 3822719 | 1.5% | 3248392 gnome-user-guide | 9217494 | 9172395 | 0.5% | 7589076 linux-image-3.2.0-4-amd64 | 32928159 | 32522228 | | 25945856 "gzip -9" is always much slower then "gzip -6". It is at most 2% better. "xz -1" is usualy faster then "gzip -9" and much better. However most packages only needs seconds to compress, so the difference will no really matter. So instead of switching to gzip -6, a switch to xz -1 would make more sense in term of size and also speed. So my proposal would be: - Don't do anything for Wheezy. Any change may break the CD creation. - Switch to xz per default for Jessie. xz -3 is often faster in compressing stuff then gzip -9. -6 needs a lot of memory, especially for compressing the files, so reducing the default to -3 may make sense and does not cost much. Bastian -- Those who hate and fight must stop themselves -- otherwise it is not stopped. -- Spock, "Day of the Dove", stardate unknown -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20121110125222.ga16...@waldi.eu.org