XFS metadata flushing design - current and future

[Christoph Hellwig]

On Tue, Aug 30, 2011 at 05:06:42PM +1000, Dave Chinner wrote:
> 
> The advantage of using our own list is that we can still then sort
> them (might be thousands of buffers we queue in a single pass)
> before submitting them for IO.  The on-stack plugging doesn't allow
> this at all, IIUC, as itis really just a FIFO list above the IO
> scheduler queues....

The on-stack plugging already sorts - manually in that code for the
request queues (not interesting for us), and currently by block number
as well using the elevator.  But the current code is more of a
guideline, I have some fairly big changes for the that area of block
layer in the pipeline.