Differential D17143
remove sync on umount -f Authored by mjg on Sep 12 2018, 11:11 PM. Tags None Referenced Files
Subscribers
Details
umount -f performs sync which completely unnecessary triggers the syncer. This happens to also cause performance problems when e.g. running synth (package building tool) which remounts filesystem for each package, unmounting with -f. Both DragonflyBSD and NetBSD have plugged this years ago.
Diff Detail
Event TimelineComment Actions commit 136e843fb06cb9682ff05052bf187c08124ec4c2 Author: Matthew Dillon <dillon@apollo.backplane.com> Date: Sat Nov 6 08:41:02 2010 -0700 umount - Remove sync() call from utility * Do not call sync() unconditionally when issuing the /sbin/umount command. Let the kernel take care of any syncing. * This may allow umount -f to operate better in situations where a mount might be stuck (such as a NFS mount), and also removes delays associated with scanning large numbers of vnodes on x86_64. and commit 8bb433caa1579a241e2c783ebc2f5549c6304531 Author: manu <manu@NetBSD.org> Date: Sat Jun 27 08:29:56 2015 +0000 Remove useless and harmful sync(2) call in umount(8) Remove sync(2) call before unmount(2) in umount(8). This sync(2) is useless since unmount(2) will perform a VFS_SYNC anyway. But moreover, this sync(2) may be harmful, as there are some situation where it cannot return (unreachable NFS server, for instance), causing umount -f to be uneffective. |