Pierre Neidhardt skribis: > Hi Ludo! > > Ludovic Courtès writes: > >> I suppose a possible agenda would be: >> >> 1. Start providing zstd susbstitutes anytime. However, most clients >> will keep choosing lzip because it usually compresses better. >> >> 2. After the next release, stop providing lzip substitutes and provide >> only gzip + zstd-19. >> >> This option has the advantage that it wouldn’t break any installation. > > But why would we keep gzip since it offers no benefits compared to zstd? > It feels like continuing to carry a (huge) burden forever... > > Besides, dropping Lzip seems like a step backward in my opinion. Users > with lower bandwidth (or simply further away from Berlin) will be > impacted a lot. > > I would opt for dropping gzip instead, only to keep zstd-19 and lzip-9 > (possibly plzip-9 if we update the bindings). > >> It’s not as nice as the ability to choose a download strategy, as we >> discussed earlier, but implementing that download strategy sounds >> tricky. > > If the user can choose their favourite substitute compression, I believe > it's usually enough since they are the best judge of their bandwidth / > hardware requirements. > > Wouldn't this simple enough? Here are a few numbers for the installation time in seconds (download time + decompression time) when fetching 580 MB of substitutes for download speeds between 0.5 MB/s and 20 MB/s. | Download speed | gzip -9 | lzip -9 | zstd -19 | |----------------+---------+---------+----------| | 0.5 | 287 | 151 | 181 | | 1.0 | 144 | 78 | 91 | | 1.5 | 97 | 54 | 61 | | 2.0 | 73 | 42 | 46 | | 2.5 | 59 | 35 | 37 | | 3.0 | 49 | 30 | 31 | | 3.5 | 42 | 27 | 26 | | 4.0 | 37 | 24 | 23 | | 4.5 | 33 | 22 | 21 | | 5.0 | 30 | 21 | 19 | | 5.5 | 28 | 19 | 17 | | 6.0 | 25 | 18 | 16 | | 6.5 | 24 | 17 | 14 | | 7.0 | 22 | 17 | 14 | | 7.5 | 21 | 16 | 13 | | 8.0 | 20 | 15 | 12 | | 8.5 | 18 | 15 | 11 | | 9.0 | 18 | 14 | 11 | | 9.5 | 17 | 14 | 10 | | 10.0 | 16 | 13 | 10 | | 11.0 | 15 | 13 | 9 | | 12.0 | 14 | 12 | 8 | | 13.0 | 13 | 12 | 8 | | 14.0 | 12 | 11 | 7 | | 15.0 | 11 | 11 | 7 | | 16.0 | 11 | 11 | 6 | | 17.0 | 10 | 10 | 6 | | 18.0 | 10 | 10 | 6 | | 19.0 | 9 | 10 | 5 | | 20.0 | 9 | 10 | 5 | When the download speed is lower than 3.5 MB/s, Lzip is better, and above that speed Zstd is better. As Gzip is never the best choice, it would make sense to drop it, even if we have to wait a little until everyone has updated their Guix daemon to a version with at least Lzip support. I think there are many people (like me) with a download speed slower than 3 MB/s, so like Pierre I would prefer keeping "lzip -9" and "zstd -19".