On Thu, Jan 22 2009, FUJITA Tomonori wrote: > On Wed, 21 Jan 2009 11:52:39 +0200 > Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote: > > > > > Currently inherited from sg.c bsg will submit asynchronous request > > at the head-of-the-queue, (using "at_head" set in the call to > > blk_execute_rq_nowait()). This is bad in situation where we want > > to keep the queues full but need the requests to execute in order. > > As I wrote, I think that blk_execute_rq_nowait inserts a request and > plugs a queue. So how can you keep the queue full? On the completion > of blk_execute_rq_nowait, the queue is empty. That's not true at all. If you submit more than one request, request 2 and up would be queued according to the orientation given. It may even include request 1 as well, what if the queue is busy doing work for someone else already? I think the patch makes sense, I also wish that the default would have been reversed so that at_back would be the default. at_back is more complex though, since it impacts existing requests for the device (it drains the scheduler queue). -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
