Re: Possible abuse of dpkg-deb -z9 for xz compressed binary packages
On 02/09/14 21:17, Changwoo Ryu wrote:
> For fonts-nanum, the default is ~300 KiB 3.5% larger than -9e. And -9e
> is not better than -8e.
I don't think anyone is arguing that higher compression settings don't
produce better compression ratios. However:
Preset DictSize CompCPU CompMem DecMem
...
-6 8 MiB 6 94 MiB 9 MiB <-
-7 16 MiB 6 186 MiB 17 MiB
-8 32 MiB 6 370 MiB 33 MiB <-
-9 64 MiB 6 674 MiB 65 MiB
... it's about cost/benefit. If we can save 300 KiB of compressed size,
but the cost is to more than triple the required memory to decompress
(from 9 MiB to 33 MiB), is that actually a worthwhile trade-off?
The d-i manual for wheezy on armel currently says that the bare minimum
RAM for wheezy is 31 MiB, the minimal recommended RAM is 64 MiB, and the
recommended RAM is 256 MiB or more. I'm sure those will increase
somewhat for jessie, but on a system with that sort of spec, packages
that need up to 65 MiB of RAM+swap to decompress (in addition to
whatever is needed for the kernel, and for the machine's actual
purpose!) seem rather greedy.
S
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