Re: Possible abuse of dpkg-deb -z9 for xz compressed binary packages
2014-09-03 17:04 GMT+09:00 Simon McVittie <smcv@debian.org>:
> 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?
I think yes. The cost is 24 MiB extra memory on installation, and
benefits are bandwidth and mirror size saving of big packages.
> 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.
I can't imagine any 31 MiB machine which needs to render megabytes of
Truetype fonts.
I think we can assume usual desktop machines for font packages.
According to the d-i manual, wheezy's minimum RAM "for desktop" is 128
MiB, and 512 MiB is recommended. For jessie, the minimum is 256 MiB
and 1 GiB is recommended. And these requirement/recommendation are far
behind of the current computer market. In practice, I have not found
any single report of OOM while installing such font packages for ~2
years.
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