On Tue, Nov 13, 2007 at 12:22:42PM +0100, Manuel Bouyer wrote:
> 
> I suspect it's because of on-board cache issues. As long as there is room
> in the cache the write is fast, and the controller does the read/modify/write
> to the disk in background (or, if you're lucky, it ends up with a full stripe
> and only has to do a write). But once the cache is full, you an I/O needs to
> wait for some pending writes to complete.

It seems as if, in that case, the driver could artificially reduce the
number of openings it presents to the ld layer.  It'd work for SCSI; is
ld a thick enough layer to make that work?

Thor