block/rnbd-clt: Support polling mode for IO latency optimization
RNBD can make double-queues for irq-mode and poll-mode. For example, on 4-CPU system 8 request-queues are created, 4 for irq-mode and 4 for poll-mode. If the IO has HIPRI flag, the block-layer will call .poll function of RNBD. Then IO is sent to the poll-mode queue. Add optional nr_poll_queues argument for map_devices interface. To support polling of RNBD, RTRS client creates connections for both of irq-mode and direct-poll-mode. For example, on 4-CPU system it could've create 5 connections: con[0] => user message (softirq cq) con[1:4] => softirq cq After this patch, it can create 9 connections: con[0] => user message (softirq cq) con[1:4] => softirq cq con[5:8] => DIRECT-POLL cq Cc: Leon Romanovsky <leonro@nvidia.com> Cc: linux-rdma@vger.kernel.org Signed-off-by:Gioh Kim <gi-oh.kim@ionos.com> Signed-off-by:
Jack Wang <jinpu.wang@ionos.com> Acked-by:
Jason Gunthorpe <jgg@nvidia.com> Reviewed-by:
Leon Romanovsky <leonro@nvidia.com> Link: https://lore.kernel.org/r/20210419073722.15351-14-gi-oh.kim@ionos.com Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
12b06533