[PATCH v3 6/6] nvme-rdma: implement polling queue map

[hch@lst.de (Christoph Hellwig)]

> +static bool nvme_rdma_poller_queue(struct nvme_rdma_queue *queue)

Can we please make this poll_queue?  or at least polled_queue?
poller sounds odd..

> -		set->nr_maps = 2 /* default + read */;
> +		set->nr_maps = HCTX_MAX_TYPES;
>  	}
>  
>  	ret = blk_mq_alloc_tag_set(set);
> @@ -864,6 +881,10 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
>  			ret = PTR_ERR(ctrl->ctrl.connect_q);
>  			goto out_free_tag_set;
>  		}
> +
> +		if (ctrl->ctrl.opts->nr_poll_queues)
> +			blk_queue_flag_set(QUEUE_FLAG_POLL,
> +				ctrl->ctrl.connect_q);

The block core is supposed to detect we can poll based on nr_maps > 2,
and then set QUEUE_FLAG_POLL automatically.  Although I got the details
wrong for PCI as well, but I just sent a fix..
> +static int nvme_rdma_poll(struct blk_mq_hw_ctx *hctx)
> +{
> +	struct nvme_rdma_queue *queue = hctx->driver_data;
> +	struct ib_cq *cq = queue->ib_cq;
> +
> +	return ib_process_cq_direct(cq, -1);

I think we can skip the cq local variable here.

Otherwise this looks really nice and simple, thanks for looking into it!

Do you have any performance number, especially with Jens' ringbuffer
code?