On 2014-09-03 13:10, Changwoo Ryu wrote: > 2014-09-03 17:04 GMT+09:00 Simon McVittie <s...@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?
That is the key question, and I believe considering the worst possible cost -- a package that cannot be unpacked, as in #757740 -- the trade-off is not worth it. > I think yes. The cost is 24 MiB extra memory on installation, and > benefits are bandwidth and mirror size saving of big packages. I think you are overestimating the benefits, and underestimating the costs. Benefits: from the numbers posted in this thread, the size savings compared to the default compression level for some sample packages are somewhere around 3% to 4%. I claim that *practical* benefits from this saving are insignificant to minor at best; counter-examples to this claim are welcome. Costs: The difference, to the default setting, in memory requirement may be only 24MiB, but you forget that with this increase, you're definitely crossing the 64MiB barrier. That is a common size for the amount of physical RAM in embedded devices, and I believe that barrier should be tested only for good reasons, otherwise stuff like #757740 happens. And finally, the cost of deviating from a default setting itself, and the implications for when that default changes, should be considered. >> 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. Fair enough. > 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. OK, but to me, that assumption seems contradictory to the motive of reducing package size. If we are assuming a sufficiently spec'ed system, say where at least 512MiB are the norm, then the cost might be tolerable, but at the same time, the 3% to 4% savings in package size will hardly benefit you. > And these requirement/recommendation are far behind of the current > computer market. For desktop and laptop computers, yes. However, embedded devices, which are becoming increasingly popular, are often memory-constrained. Christian -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/540767a4.40...@kvr.at
