mlx4 devices (ConnectX-2, ConnectX-3) has a limitation where rdma read work queue entries cannot exceed 512 bytes. A rdma_read wqe needs to fit in 512 bytes: - wqe control segment (16 bytes) - rdma segment (12 bytes) - scatter elements (16 bytes each)
So max_sge_rd should be: (512 - 16 - 12) / 16 = 30. Signed-off-by: Sagi Grimberg <[email protected]> --- drivers/infiniband/hw/mlx4/main.c | 2 +- include/linux/mlx4/device.h | 11 +++++++++++ 2 files changed, 12 insertions(+), 1 deletions(-) diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c index 3889723..d8453f1 100644 --- a/drivers/infiniband/hw/mlx4/main.c +++ b/drivers/infiniband/hw/mlx4/main.c @@ -499,7 +499,7 @@ static int mlx4_ib_init_device_flags(struct ib_device *ibdev) ibdev->max_qp_wr = dev->dev->caps.max_wqes - MLX4_IB_SQ_MAX_SPARE; ibdev->max_sge = min(dev->dev->caps.max_sq_sg, dev->dev->caps.max_rq_sg); - ibdev->max_sge_rd = ibdev->max_sge; + ibdev->max_sge_rd = MLX4_MAX_SGE_RD; ibdev->max_cq = dev->dev->quotas.cq; ibdev->max_cqe = dev->dev->caps.max_cqes; ibdev->max_mr = dev->dev->quotas.mpt; diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h index baad4cb..90c12f0 100644 --- a/include/linux/mlx4/device.h +++ b/include/linux/mlx4/device.h @@ -425,6 +425,17 @@ enum { }; enum { + /* + * Max wqe size for rdma read is 512 bytes, so this + * limits our max_sge_rd as the wqe needs to fit: + * - ctrl segment (16 bytes) + * - rdma segment (12 bytes) + * - scatter elements (16 bytes each) + */ + MLX4_MAX_SGE_RD = (512 - 16 - 12) / 16 +}; + +enum { MLX4_DEV_PMC_SUBTYPE_GUID_INFO = 0x14, MLX4_DEV_PMC_SUBTYPE_PORT_INFO = 0x15, MLX4_DEV_PMC_SUBTYPE_PKEY_TABLE = 0x16, -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
