Series improving plugging for fast devices, but some fixes in here too. 1-2 are improvements around plugging accounting. Changes the behavior a bit, but works fine for me. 3-6 add a ->commit_rqs() hook and implement it in drivers that use (or will use) bd->last to optimize IO submission. If a driver currently uses bd->last to know if it's needed to kick the hardware into action, there are cases where we flag bd->last == false, but then fail to submit any further IO due to other resource constraints. We probably get saved by the fact that this happens for the case where we have pending IO and that will eventually guarantee forward progress, but we really should kick IO into gear at that point. 7-8 improve plugging for blk-mq. In terms of improvements, for virtualized nvme, I've seen a 2-x IOPS improvement with proper handling of bd->last with this series. -- Jens Axboe
