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.
Signed-off-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/nvme/host/rdma.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 1eb4438..9ae261d 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 {
@@ -249,7 +250,7 @@ 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 +375,9 @@ static int nvme_rdma_dev_get(struct nvme_rdma_device *dev)
goto out_free_pd;
}
+ ndev->num_inline_segments = min(NVME_RDMA_MAX_INLINE_SEGMENTS,
+ ndev->dev->attrs.max_sge - 1);
+ pr_debug("num_inline_segments = %u\n", ndev->num_inline_segments);
list_add(&ndev->entry, &device_list);
out_unlock:
mutex_unlock(&device_list_mutex);
@@ -1086,19 +1090,27 @@ 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;
}
@@ -1191,13 +1203,13 @@ static int nvme_rdma_map_data(struct nvme_rdma_queue *queue,
return -EIO;
}
- if (count == 1) {
+ if (count <= dev->num_inline_segments) {
if (rq_data_dir(rq) == WRITE && nvme_rdma_queue_idx(queue) &&
blk_rq_payload_bytes(rq) <=
nvme_rdma_inline_data_size(queue))
- return nvme_rdma_map_sg_inline(queue, req, c);
+ return nvme_rdma_map_sg_inline(queue, req, c, count);
- if (dev->pd->flags & IB_PD_UNSAFE_GLOBAL_RKEY)
+ if (count == 1 && dev->pd->flags & IB_PD_UNSAFE_GLOBAL_RKEY)
return nvme_rdma_map_sg_single(queue, req, c);
}
--
1.8.3.1
--
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