Jens Axboe wrote: > 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). > bsg only sends BLOCK_PC commands, I think these are not held in the scheduler queue, right? I think like you at_back is the default to use, but this is historic compatibility with SG that had problems with ABORT and such not. With my patch I give the user a choice and be done with it. Thanks Boaz -- 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
