From 64a741c1eaa83e34a8846c7196feb8e45785bebc Mon Sep 17 00:00:00 2001 From: Steve Wise Date: Wed, 20 Jun 2018 07:15:05 -0700 Subject: [PATCH] nvme-rdma: support up to 4 segments of inline data Allow up to 4 segments of inline data for NVMF WRITE operations. This reduces latency for small WRITEs by removing the need for the target to issue a READ WR for IB, or a REG_MR + READ WR chain for iWarp. Also cap the inline segments used based on the limitations of the device. Reviewed-by: Sagi Grimberg Reviewed-by: Max Gurtovoy Signed-off-by: Steve Wise Signed-off-by: Christoph Hellwig --- drivers/nvme/host/rdma.c | 38 +++++++++++++++++++++++++++----------- 1 file changed, 27 insertions(+), 11 deletions(-) diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c index 518c5b09038c..363f73fe549c 100644 --- a/drivers/nvme/host/rdma.c +++ b/drivers/nvme/host/rdma.c @@ -40,13 +40,14 @@ #define NVME_RDMA_MAX_SEGMENTS 256 -#define NVME_RDMA_MAX_INLINE_SEGMENTS 1 +#define NVME_RDMA_MAX_INLINE_SEGMENTS 4 struct nvme_rdma_device { struct ib_device *dev; struct ib_pd *pd; struct kref ref; struct list_head entry; + unsigned int num_inline_segments; }; struct nvme_rdma_qe { @@ -117,6 +118,7 @@ struct nvme_rdma_ctrl { struct sockaddr_storage src_addr; struct nvme_ctrl ctrl; + bool use_inline_data; }; static inline struct nvme_rdma_ctrl *to_rdma_ctrl(struct nvme_ctrl *ctrl) @@ -249,7 +251,7 @@ static int nvme_rdma_create_qp(struct nvme_rdma_queue *queue, const int factor) /* +1 for drain */ init_attr.cap.max_recv_wr = queue->queue_size + 1; init_attr.cap.max_recv_sge = 1; - init_attr.cap.max_send_sge = 1 + NVME_RDMA_MAX_INLINE_SEGMENTS; + init_attr.cap.max_send_sge = 1 + dev->num_inline_segments; init_attr.sq_sig_type = IB_SIGNAL_REQ_WR; init_attr.qp_type = IB_QPT_RC; init_attr.send_cq = queue->ib_cq; @@ -374,6 +376,8 @@ nvme_rdma_find_get_device(struct rdma_cm_id *cm_id) goto out_free_pd; } + ndev->num_inline_segments = min(NVME_RDMA_MAX_INLINE_SEGMENTS, + ndev->dev->attrs.max_sge - 1); list_add(&ndev->entry, &device_list); out_unlock: mutex_unlock(&device_list_mutex); @@ -925,6 +929,9 @@ static void nvme_rdma_reconnect_ctrl_work(struct work_struct *work) if (ret) goto requeue; + if (ctrl->ctrl.sgls & (1 << 20)) + ctrl->use_inline_data = true; + if (ctrl->ctrl.queue_count > 1) { ret = nvme_rdma_configure_io_queues(ctrl, false); if (ret) @@ -1090,19 +1097,27 @@ static int nvme_rdma_set_sg_null(struct nvme_command *c) } static int nvme_rdma_map_sg_inline(struct nvme_rdma_queue *queue, - struct nvme_rdma_request *req, struct nvme_command *c) + struct nvme_rdma_request *req, struct nvme_command *c, + int count) { struct nvme_sgl_desc *sg = &c->common.dptr.sgl; + struct scatterlist *sgl = req->sg_table.sgl; + struct ib_sge *sge = &req->sge[1]; + u32 len = 0; + int i; - req->sge[1].addr = sg_dma_address(req->sg_table.sgl); - req->sge[1].length = sg_dma_len(req->sg_table.sgl); - req->sge[1].lkey = queue->device->pd->local_dma_lkey; + for (i = 0; i < count; i++, sgl++, sge++) { + sge->addr = sg_dma_address(sgl); + sge->length = sg_dma_len(sgl); + sge->lkey = queue->device->pd->local_dma_lkey; + len += sge->length; + } sg->addr = cpu_to_le64(queue->ctrl->ctrl.icdoff); - sg->length = cpu_to_le32(sg_dma_len(req->sg_table.sgl)); + sg->length = cpu_to_le32(len); sg->type = (NVME_SGL_FMT_DATA_DESC << 4) | NVME_SGL_FMT_OFFSET; - req->num_sge++; + req->num_sge += count; return 0; } @@ -1195,15 +1210,16 @@ static int nvme_rdma_map_data(struct nvme_rdma_queue *queue, goto out_free_table; } - if (count == 1) { + if (count <= dev->num_inline_segments) { if (rq_data_dir(rq) == WRITE && nvme_rdma_queue_idx(queue) && + queue->ctrl->use_inline_data && blk_rq_payload_bytes(rq) <= nvme_rdma_inline_data_size(queue)) { - ret = nvme_rdma_map_sg_inline(queue, req, c); + ret = nvme_rdma_map_sg_inline(queue, req, c, count); goto out; } - if (dev->pd->flags & IB_PD_UNSAFE_GLOBAL_RKEY) { + if (count == 1 && dev->pd->flags & IB_PD_UNSAFE_GLOBAL_RKEY) { ret = nvme_rdma_map_sg_single(queue, req, c); goto out; } -- 2.39.5