On Mon, Jun 14, 2010 at 04:21:43PM -0700, Andrew Morton wrote: > Yup. > > But then, this all really should be done at the block layer so other > io-submitting-paths can benefit from it. > > IOW, maybe "the sort queue is the submission queue" wasn't a good idea. Even if has not effect on the actual I/O patters it has a massive benefit for the filesystem. When probing delalloc/unwritten space at least XFS does try to convert a larger extent forward from the index, but doesn't bother to go backwards. By providing the trivial sort here we make life a lot easier for the filesystem. In addition to that we do get better I/O patters especially with short queues as smart writepage implementatons will also submit the next few pages, which is essentially free given how the storage works. This means we already have a page cleaned before we might even submit it without sorting. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>