Set the maximal data transfer size according to device capabilities.
For example, for T10-DIF offload by supporting RDMA HCA, one uses
RDMA/rw API that limits the IO operation to use a single MR with 256
pages at the most. Limit the mdts according to RDMA/rw API and even
decrease it in order to avoid multiple splits by the local block layer
for large IOs to ease on the CPU on the target side.
Signed-off-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>
---
drivers/nvme/target/rdma.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index 37d262a..2227adf 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -30,6 +30,7 @@
#define NVMET_RDMA_DEFAULT_INLINE_DATA_SIZE PAGE_SIZE
#define NVMET_RDMA_MAX_INLINE_SGE 4
#define NVMET_RDMA_MAX_INLINE_DATA_SIZE max_t(int, SZ_16K, PAGE_SIZE)
+#define NVMET_RDMA_T10_PI_MDTS 5
struct nvmet_rdma_cmd {
struct ib_sge sge[NVMET_RDMA_MAX_INLINE_SGE + 1];
@@ -1602,6 +1603,21 @@ static void nvmet_rdma_disc_port_addr(struct nvmet_req *req,
}
}
+static u8 nvmet_rdma_set_mdts(struct nvmet_ctrl *ctrl)
+{
+ struct nvmet_port *port = ctrl->port;
+ struct rdma_cm_id *cm_id = port->priv;
+ u32 max_pages;
+
+ if (ctrl->pi_support) {
+ max_pages = rdma_rw_fr_page_list_len(cm_id->device, true);
+ /* Assume mpsmin == device_page_size == 4KB */
+ return min(ilog2(max_pages), NVMET_RDMA_T10_PI_MDTS);
+ }
+
+ return 0;
+}
+
static const struct nvmet_fabrics_ops nvmet_rdma_ops = {
.owner = THIS_MODULE,
.type = NVMF_TRTYPE_RDMA,
@@ -1612,6 +1628,7 @@ static void nvmet_rdma_disc_port_addr(struct nvmet_req *req,
.queue_response = nvmet_rdma_queue_response,
.delete_ctrl = nvmet_rdma_delete_ctrl,
.disc_traddr = nvmet_rdma_disc_port_addr,
+ .set_mdts = nvmet_rdma_set_mdts,
};
static void nvmet_rdma_remove_one(struct ib_device *ib_device, void *client_data)
--
1.8.3.1
