On Thu, Jun 23, 2016 at 12:20:38AM +0200, Hans van Kranenburg wrote: > > Printing 'usage' is not default as it's quite slow, it uses the search ioctl > > and probably not in the best way, or there's some other issue in the > > implementation. > > Interesting. > > So after reading this, I wrote a little test to test some scenarios: > > https://github.com/knorrie/python-btrfs/commit/1ca99880dfa0e14b148f3d9e2b6b381b781eb52d > > It's very clear that the most optimal way of doing this search is to > have nr_items=1 and if possible, specify the length in offset.
And that solved it. [...] > It seems that searching in the empty space between > (vaddr BLOCK_GROUP_ITEM length+1) and > (vaddr BLOCK_GROUP_ITEM ULLONG_MAX) > is really expensive, while there's absolutely nothing to find. Yeah, the few BLOCK_GROUP_ITEMs are scattered among tons of EXTENT_ITEMs -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
