On 2018-03-11 21:51:05 [+0100], Balint Reczey wrote: > For the recompressed firefox .deb (Ubuntu's > firefox_58.0.2+build1-0ubuntu0.17.10.1_amd64.deb) increased ~9% in > size but decompressed in <20% of the original time:
So you are saying that the decompression speed that is the bottleneck here? I *assumed* that it is mostly the disk speed since I get around 60 to 80MiB/sec out of xz. > $ du -s firefox-*deb > 43960 firefox-xz.deb > 47924 firefox-zstd.deb 48M linux-image-5.5.0-1-amd64_5.5.13-2_amd64.data.tar.xz 54M linux-image-5.5.0-1-amd64_5.5.13-2_amd64.data.tar.19.zstd 766M linux-image-5.5.0-1-amd64-dbg_5.5.13-2_amd64.data.tar.xz 901M linux-image-5.5.0-1-amd64-dbg_5.5.13-2_amd64.data.tar.19.zstd zstd -19 -T16 |linux-image-5.5.0-1-amd64-dbg_5.5.13-2_amd64.data.tar : Completed in 287.37 sec (cpu load : 1533%) | |real 4m47,416s |user 73m23,825s |sys 0m2,753s | xz -T16 | real 4m15,447s | user 66m51,572s | sys 0m3,201s > $ rm -rf firefox-xz/* ;time dpkg-deb -R firefox-xz.deb firefox-xz/ > real 0m4,270s > user 0m4,220s > sys 0m0,630s > $ rm -rf firefox-zstd/* ;time dpkg-deb -R firefox-zstd.deb firefox-zstd/ > real 0m0,765s > user 0m0,556s > sys 0m0,462s So this looks impressive. Is dpkg-deb also performing sync() on the output or is the report when the files hit the disk cache? Either way, should be noticeable on ssd/nvme which write at higher performance. > Tests on the full Ubuntu main archive showed ~6% average increase in > the size of the binary packages. I guess the vast majority of packages are small and hardly increase in size. The bigger packages then increase more. > The patches are also available on Salsa [2]. While I read the whole thread here, I did not find any consent other than discuss it d-devel. Is this still the case? > Cheers, > Balint Sebastian
