Rahul Siddharthan pointed at this post as evidence of softupdates not working as quickly as it used to, for FreeBSD and by extension DragonFly. Matt Dillon replied that:
“FreeBSD-5 has a lot overhead, especially when it comes to the buffer manipulation that softupdates does. DFly should be nearly the same as 4.x in regards to FS performance.
There isn’t much I can do about softupdates but the (slowly progressing) namecache work will eventually allow us to release the exclusive lock on the directory vnode during directory searches and this will bring up our lots-of-little-file benchmark numbers considerably.
Another issue that slows down filesystem operations is the busy-page lockout that occurs when the system is writing data to disk and some other operation wants to modify the page undergoing I/O. That is ”on the table’ as well.”