On Thu, 2010-07-29 at 22:17 +1000, Dave Chinner wrote: > On Wed, Jul 28, 2010 at 03:00:48PM -0700, Mingming Cao wrote: > > On Wed, 2010-07-28 at 01:38 +0200, Christian Stroetmann wrote: > > > At the 28.07.2010 00:00, Ben Chociej wrote: > > > Wouldn't this feature be useful for other file systems as well, so that > > > a more general and not an only Btrfs related solution is preferable? > > > > > > > Would certainly nice to add this feature to all filesystem, but right > > now btrfs is the only fs which have multiple device support in itself. > > Why does it even need multiple devices in the filesystem? All the > filesystem needs to know is the relative speed of regions of it's > block address space and to be provided allocation hints. everything > else is just movement of data. You could keep the speed information > in the device mapper table and add an interface for filesystems to > query it, and then you've got infrastructure that all filesystems > could hook into. > > The tracking features dont' appear to have anything btrfs specific > in them, so t iseems wrong to implement it there just because you're > only looking at btrfs' method of tracking multiple block devices > and moving blocks.... > I agree hot data tracking could be done at vfs layer. The current hot data temperature calculation and indexing code is very self-contained, and could be reuse to other fs or move up to vfs. We could define a common interface to export to hot data tempreture out. The relocation eventually has to be filesystem specific. btrfs does cow and knows where is the data on/off SSD directly makes the relocation to and from very straightforward. Mingming -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
