On Mon, Dec 10 2007, jidong xiao wrote: > Hi, > > I am reading the source code of block I/O layer, and now seeing there > saying "ordering by draining" or "ordering by tag" in > include/blkdev.h,and the comments in that file says: "Hardbarrier is > supported with one of the following methods", but what do these two > methods exactly mean?
ordering by draining means that you empty the pending queue of requests and then flush the cache to prevent a later issue of a new request to reach the platter before the older ones. order by tag means that the hw has a way of being told not to reorder beyond the barrier, in which case you don't have to drain the queue. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
