On Tue, Feb 26, 2019 at 02:02:14PM +1100, Dave Chinner wrote: > > Or what is the exact size of sub-page IO in xfs most of time? For > > Determined by mkfs parameters. Any power of 2 between 512 bytes and > 64kB needs to be supported. e.g: > > # mkfs.xfs -s size=512 -b size=1k -i size=2k -n size=8k .... > > will have metadata that is sector sized (512 bytes), filesystem > block sized (1k), directory block sized (8k) and inode cluster sized > (32k), and will use all of them in large quantities. If XFS is going to use each of these in large quantities, then it doesn't seem unreasonable for XFS to create a slab for each type of metadata?