On Sun, Jan 23, 2022 at 5:30 PM Robert-André Mauchin <zebo...@gmail.com> wrote: > > Hi, > > So I have an annoying bug that started near the beginnings of F35. > My papirus-icon-theme became very slow to install: > https://bugzilla.redhat.com/show_bug.cgi?id=2029709#c18 > > During the installation, all the files are copied, then renamed by rpm > (no idea why it works like this). > > It works fast in a Mock chroot but incredibly slow on bare metal. > > I've done a small test of moving files: > > [root@cassini icons]# mkdir test > [root@cassini icons]# for (( i = 0; i < 10000; i++ )) do > test/file_$i; > done > [root@cassini icons]# cd test > > On host: > > time $(for f in *; do mv "$f" "${f%}.txt"; done) > real 2m3,500s > user 0m3,966s > sys 2m0,431s > > In nspawn container: > > <mock-chroot> sh-5.1# time $(for f in *; do mv "$f" "${f%}.txt"; done) > real 0m6.702s > user 0m4.237s > sys 0m3.344s > > Since papirus-icon-theme contains more than 100,000 (small) files, it is > a problem. One minute of waiting is ok, 20 mn is not. > > What can cause this? I read that nspawn virtualizes the file system, > could it be file system related on the host? (I use btrfs btw) > > Any input welcome!
What file system is being used in each case? This is a bit obscure but... cp and mv use reflink=auto. On XFS and Btrfs this means it'll make reflinks (copies metadata, doesn't duplicate the data extents) if it can. Falling back to a full copy (metadata and data extents). It might not be possible due to an obscure VFS rule that disallows reflinks (for reasons I don't understand) when the copy or move crosses mount point boundaries. This includes bind mounts of directories. Bind mounts are also what are employed behind the scene with 'mount -o subvol' mount option on Btrfs, which we use by default in Fedora Workstation and Cloud Edition, and all the desktop spins. The nspawn container, I'm not super familiar with how it works. I think on Btrfs, it will create nested subvolumes, i.e. they are not mounted with the subvol mount option, hence no mount point boundary. But on other file systems, I think nspawn creates a loop mounted file system? -- Chris Murphy _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
