On Mon, Feb 18, 2008 at 04:18:23PM +0100, Andi Kleen wrote: > On Mon, Feb 18, 2008 at 09:16:41AM -0500, Theodore Tso wrote: > > ext3 tries to keep inodes in the same block group as their containing > > directory. If you have lots of hard links, obviously it can't really > > do that, especially since we don't have a good way at mkdir time to > > tell the filesystem, "Psst! This is going to be a hard link clone of > > that directory over there, put it in the same block group". > > Hmm, you think such a hint interface would be worth it? It would definitely help ext2/3/4. An interesting question is whether it would help enough other filesystems that's worth adding. > > necessarily removing the dir_index feature. Dir_index speeds up > > individual lookups, but it slows down workloads that do a readdir > > But only for large directories right? For kernel source like > directory sizes it seems to be a general loss. On my todo list is a hack which does the sorting of directory inodes by inode number inside the kernel for smallish directories (say, less than 2-3 blocks) where using the kernel memory space to store the directory entries is acceptable, and which would speed up dir_index performance for kernel source-like directory sizes --- without needing to use the spd_readdir LD_PRELOAD hack. But yes, right now, if you know that your directories are almost always going to be kernel source like in size, then omitting dir_index is probably goint to be a good idea. - Ted - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
