On Fri, Nov 20, 2009 at 02:05:11PM -0600, David Nicol wrote: > On Fri, Nov 20, 2009 at 1:50 PM, Chris Mason <chris.ma...@oracle.com> wrote: > > COW semantics require touching btree nodes all the way up to the root of > > the btree, but this is different from the directory. Directories are > > stored in the btree, but you won't have to touch more than 8 or so btree > > levels regardless of how deep your directory tree is. > > > > -chris > > Thanks for straightening me out on that point. > > Still, 8 might be a lot. > > Regardless of the decoupling of btrees and directories, am I right in > thinking that mounted subvolumes instead of directories would (1) > reduce contention
It might, it depends on the workload. But yes, one point of big contention is the root node of the btree and each subvolume has its own root. > (2) reduce the number of levels touched since number > of levels is a function of the number of fs entities in the volume, > therefore It depends on the overall btree size. Probably. > (3) defining a file system entity that transparently becomes > a mounted subvolume (by transparently I mean without an additional > mount command) and (4) crafting a utility to streamline > creation-and-implied-mounting of the entity type from #3 would make > sense? Sure. It definitely makes sense to explore the subvolume and snapshotting user interfaces. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
