On Thu, Jan 16, 2014 at 02:12:27PM -0500, Theodore Ts'o wrote: > An 8MB file will require two indirect blocks. If you are using > extents, almost certainly it will fit inside the inode, which means we > don't need any external metadata blocks. That massively speeds up > fsck time, and unlink time, and it also speeds up the random read case > since the best way to optimize a seek is to eliminate it. :-) > I understand that for your use case, it would be hard to move to using > extents right away. But I think you'd see so many improvements from > going to ext4 and extents that it might be more efficient to optimize > an indirect blocok scheme. Unfortunately, the improvements from extents for our use-case are not enough to outweigh the other costs of deployment. I think I've figured out a hack that results in the system doing most of what I want it to do: I've removed EXT4_MB_HINT_DATA in ext4_alloc_blocks(). With that change, the allocator is giving me mostly sequential allocations. Hopefully that doesn't have any other negative side effects. -ben > - Ted -- "Thought is the essence of where you are now." -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
