On Wed, Apr 18, 2012 at 01:02:08PM +1000, Dave Chinner wrote: > In actual fact, on my 12 disk RAID0 array, XFS is faster with > unwritten extents *enabled* than when hacked to turn them off. Can you explain why this is the case? It seems... counterintuitive. The only explanation I can think of is that your code paths when unwritten extents are disabled haven't been optimized, in which case the comparison between using and not using unwritten extents might not be valid. Is there anything going on other than _not_ mutating the extent tree (and all of the logical journaling that would go along with it)? Hacking to turn them off means it should be doing *less* work, so I would expect at worst it would be the same speed as using extent written extents. If it's faster to use unwritten extents, something very wierd must be going on.... - Ted -- 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
