Hi, There is a kernel process, 'syncer', that periodically fsync()s dirty vnodes on each filesystem and syncs each filesystem.
This patchset (http://leaf.dragonflybsd.org/~vsrinivas/syncer) {or http://gitweb.dragonflybsd.org/~vsrinivas/vmflush if you prefer git trees} allows filesystems to flag themselves with MNT_THR_SYNC; if they are so flagged, their periodic fsync() and sync paths will be called from a per-filesystem thread. The patchset doesn't make any filesystems that way, but I've tested a little bit with UFS and tmpfs. Any comments/patch reviews/etc would be greatly appreciated! Thanks, -- vs;
