-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 'Rusty Bird' via qubes-users: > Marek Marczykowski-Górecki: > > On Wed, Oct 16, 2024 at 04:28:14PM +0000, Rusty Bird wrote: > > > Also, on file-reflink > > > systems, where the dom0 root filesystem is storing (possibly many > > > terabytes worth of) VM volumes, fstrim can take really long. E.g. > > > here on my main Btrfs system, which is otherwise quite fast: > > > > > > # time fstrim /var/tmp/ > > > real 4m29.240s > > > > But that takes long only if there is really a lot of data to discard, > > no? > > # for i in 1 2 3; do time fstrim /var/tmp/; done 2>&1 | grep real > real 4m24.308s > real 4m34.060s > real 4m29.806s > > I don't see anything in Btrfs tracking which unused blocks it has > already issued discards for. Or in ext4, but it doesn't matter with > the small ext4 dom0 root fs in an LVM Thin installation.
Actually ext4 does keep track: https://serverfault.com/questions/1113127/fstrim-is-very-slow-on-xfs-and-always-return-same-value-unlike-ext4 > So a large fs > that's neither almost empty nor almost full has to at least generate a > gigantic list of (due to fragmentation) probably rather small ranges > of blocks to be discarded in response to every fstrim and forward it > through the block subsystem (which I don't think is keeping track > either?) to the drive. Only after all of that overhead, I guess the > drive might respond faster if it had already done most of the work > last time. Rusty -----BEGIN PGP SIGNATURE----- iQKTBAEBCAB9FiEEhLWbz8YrEp/hsG0ERp149HqvKt8FAmcQHAJfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldDg0 QjU5QkNGQzYyQjEyOUZFMUIwNkQwNDQ2OUQ3OEY0N0FBRjJBREYACgkQRp149Hqv Kt//lQ/9GtwhYOxlQCr1FMVt8jf6VSdogeZzWnErQO7ldaujc730hZcHgmbtincl 1Eo81cLy5gQ8fKzBoZ7qNhNd6VjvFJirnhHs6zqQKFCTbOs+FAM2pGViAEGLtT8r BST11UoTcrN+RBBgnd5o1wP99G/8ZWPOkB/bTAYPb6ZmYlq+oikl7fG/GbeXXFZh keHdjdiS1uutwA2Ip9pZTkCGuyUd4xy3Y9aHQm2OuuQeYln+ZUUMMeo1LqESWLl1 S1m4CRLLkN8l8StNkz3jf7605+hiyY+NPdbYMXlRl9HhxKugORMAsrzFFVkk+80h rFrxz49JLp8Cg55X0cShZNYpfaH3eOGw7PS932B+6q0qrHkb7yhCATj2VxBVdCD+ JOzaflxC32XyXDVcJrrhhfwrwoqySBVo/HSZ3O9hhvWEV9CLe+KgivsR72Ryy+eF n1d0CxjYHEN4qWRN0qTG/YatEJqkZ1bWdtG6rAQrRvkNOomPo3ikGpqw9WKnkhAN xfCGnoxjNOkCDYyrqIBhRfVKjMldIlkNRnwGGKjLARJJ08Wjmt+fiGeNeOn4qXOK jwElSeaui2nHOnje1nSxrIsIotwUIK/msFjbJ/lt7xjvna/CgftMPysztHhLrjZU I6OuIun83nkQnGTy3aAU5ohEWGVhUCB6w3RxqzTv+bWdaucBfmA= =PCuB -----END PGP SIGNATURE----- -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to qubes-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/ZxAcAga7JycORHlJ%40mutt.
