Re: [PATCH 0/6] writeback time order/delay fixes take 3

David Chinner
2007-08-23T02:33:38Z

On Wed, Aug 22, 2007 at 09:18:41AM +0800, Fengguang Wu wrote:
> On Tue, Aug 21, 2007 at 08:23:14PM -0400, Chris Mason wrote:
> Notes:
> (1) I'm not sure inode number is correlated to disk location in
> filesystems other than ext2/3/4. Or parent dir?

The correspond to the exact location on disk on XFS. But, XFS has it's
own inode clustering (see xfs_iflush) and it can't be moved up
into the generic layers because of locking and integration into
the transaction subsystem.

> (2) It duplicates some function of elevators. Why is it necessary?

The elevators have no clue as to how the filesystem might treat adjacent
inodes. In XFS, inode clustering is a fundamental feature of the inode
reading and writing and that is something no elevator can hope to
acheive....

Cheers,

Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group