3 ms·
The main performance problem in pacman as far as I can tell is really slow xz decompression. This is mostly important for large packages: $ time xzcat /var
by phiresky 7y ago
The main performance problem in pacman as far as I can tell is really slow xz decompression. This is mostly important for large packages:
$ time xzcat /var/cache/pacman/pkg/cuda-10.1.243-1-x86_64.pkg.tar.xz >/dev/null
1:17,33 total
Just decompressing that 1.8GB package takes 77 seconds.
There was a discussion in April to switch compression to zstd - which reduces the decompression time for that package to only 4 seconds (!) while keeping the same file size. That way the disk is the bottleneck again, as it should be. That switch would be awesome, but it looks like it's not happening currently.
- sigotirandolas 7y agoIf you have a fast connection, xz decompression may be the bottleneck, but in some places, downloading that 1.8GB can easily take an hour or more. So I’m not sure whether this is the bottleneck in the usual case. I would also be interested to see if it’s using parallel decompresssion when possible. I have an intuition it doesn’t, since I have always found Arch defaulting to single thread decompression, e.g in makepkg or for compressing with mkinitcpio.
- aiNohY6g 7y agolink: https://lists.archlinux.org/pipermail/arch-dev-public/2019-March/029520.html https://lists.archlinux.org/pipermail/arch-dev-public/2019-M...