James Bottomley wrote: > On Thu, 2005-04-21 at 09:20 +0900, Tejun Heo wrote: > >> Hello, James. >> >>James Bottomley wrote: >> >>>On Wed, 2005-04-20 at 08:15 +0900, Tejun Heo wrote: >>> >>> >>>>- * Insert this command at the head of the queue for it's device. >>>>- * It will go before all other commands that are already in the queue. >>>>- * >>>>- * NOTE: there is magic here about the way the queue is plugged if >>>>- * we have no outstanding commands. >>>>- * >>>>- * Although this *doesn't* plug the queue, it does call the request >>>>- * function. The SCSI request function detects the blocked condition >>>>- * and plugs the queue appropriately. >>> >>> >>>This comment still looks appropriate to me ... why do you want to remove >>>it? >>> >> >> Well, the thing is that we don't really care what exactly happens to >>the queue or how the queue is plugged or not. All we need to do are to >>requeue the request and kick the queue in the ass. Hmmm, maybe I should >>keep the comment about how the request will be put at the head of the >>queue, but the second part about plugging doesn't really belong here, I >>think. > > > Really? We do care greatly. If you requeue with no other outstanding > commands to the device, the block queue will never restart unless it's > plugged, and the device will hang. The comment is explaining how this > happens. > Yes, you're right. My point was that that's scsi_run_queue()'s business. We don't need to comment that deep when we're requeueing a request. After we put a request on a queue, we kick the queue. It's the queue running function's responsibility to determine whether to run the request right away or to defer processing (and thus plug). I wasn't saying that the eventual plugging isn't necessary, but that the comment is sort of excessive. Anyways, if you think the comment is necessary, I don't feel strong against it. I'll rewrite above comment to fit the new code and repost this patch soon. > >> Yes, that will be more efficient but I don't think it would make >>any >>noticeable difference. IMO, universally using scsi_run_queue() to >>kick >>scsi request queues is better than mixing blk_run_queue() and >>scsi_run_queue() for probably unnoticeable optimization. If we start >>to >>mix'em, we need to rationalize why specific one is chosen in specific >>places and that's just unnecessary. > > > Fair enough. Thanks. -- tejun - : 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
