Hi, I was wondering if we need the extent-status tree for DAX-like devices ? Says here that it can get consume a lot of memory and offer poor performance if the on-DAX file is fragmented. Without the status tree, one could simple walk the on-DAX extent tree to get to the file data pages and this is possible with DAX-like devices. http://lxr.free-electrons.com/source/fs/ext4/extents_status.c#L117 A few simple experiments with filebench's random read workload clearly bring out the difference in performance with a fragmented and contiguous file on-DAX. A lot of time is spent in walking the status tree, which can be avoided, I guess. Please let me know what you think. -- S. Nalli Graduate Student, Computer Sciences University of Wisconsin-Madison, USA