Re: fallocate overhead

Chris Mason
2009-08-13T14:45:23Z

On Thu, Aug 13, 2009 at 04:07:32PM +0200, Markus Trippelsdorf wrote:
> I was playing with the new hdparm wiper script (
> http://sourceforge.net/projects/hdparm/files/) on my Vertex SSD and
> it appears that btrfs needs a huge space overhead when dealing with
> fallocate system calls. Basically what the wiper script does is to
> fallocate one huge file using all free space minus a safety margin.
> And this margin has to be about 30% on btrfs, e.g.:

We're actively fixing this ;) The margin is just a hard coded limit to
try and avoid enospc oopsen. It should improve in 2.6.32.

-chris