Commit 5b333e40 authored by Alexey Marchuk's avatar Alexey Marchuk Committed by Tomasz Zawadzki
Browse files

nvmf/rdma: Prioritize partial RDMA_READ operations 



RDMA transport was updated to send part of RDMA_READ
operations in order to fully utilize QP capacity.
But requests which sent only part of RDMA_READ operations
were put to the end of a list, their latency could be greatly
increased. To avoid latency increase, put partially completed
requests to the head of the list, i.e increase their priority
over new requests.

Signed-off-by: default avatarAlexey Marchuk <alexeymar@nvidia.com>
Reported-by: default avatarPeng Xu <jingmamour@gmail.com>
Change-Id: Ib27783f5c6ec368f591b859c211a42d2965841ff
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/23302


Community-CI: Mellanox Build Bot
Reviewed-by: default avatarShuhei Matsumoto <smatsumoto@nvidia.com>
Reviewed-by: default avatarBen Walker <ben@nvidia.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
parent e1ad3584

lib/nvmf/rdma.c

+3 −2
Original line number Diff line number Diff line
@@ -4723,10 +4723,11 @@ nvmf_rdma_poller_poll(struct spdk_nvmf_rdma_transport *rtransport, 
				rqpair->current_read_depth--;

				/* wait for all outstanding reads associated with the same rdma_req to complete before proceeding. */

				if (rdma_req->num_outstanding_data_wr == 0) {

					if (spdk_unlikely(rdma_req->num_remaining_data_wr)) {

					if (rdma_req->num_remaining_data_wr) {

						/* Only part of RDMA_READ operations was submitted, process the rest */

						nvmf_rdma_request_reset_transfer_in(rdma_req, rtransport);

						STAILQ_INSERT_TAIL(&rqpair->pending_rdma_read_queue, rdma_req, state_link);

						/* Prioritize partially handled request over others to avoid latency increase */

						STAILQ_INSERT_HEAD(&rqpair->pending_rdma_read_queue, rdma_req, state_link);

						rdma_req->state = RDMA_REQUEST_STATE_DATA_TRANSFER_TO_CONTROLLER_PENDING;

						nvmf_rdma_request_process(rtransport, rdma_req);

						break;