diff options
| author | Sagi Grimberg | 2015-10-28 13:28:15 +0200 |
|---|---|---|
| committer | Doug Ledford | 2015-12-08 12:42:44 -0500 |
| commit | a5e14ba334e202c58e45ef47414ec94c585c1a8c (patch) | |
| tree | b04bac58103e9551d2107aa96295db010c5695a2 /include/linux/mlx4 | |
| parent | 533708867dd6388f643f12c87465b59e732d729d (diff) | |
mlx4: Expose correct max_sge_rd limit
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 (16 bytes)
- scatter elements (16 bytes each)
So max_sge_rd should be: (512 - 16 - 16) / 16 = 30.
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Diffstat (limited to 'include/linux/mlx4')
| -rw-r--r-- | include/linux/mlx4/device.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h index 7501626ab529..d3133be12d92 100644 --- a/include/linux/mlx4/device.h +++ b/include/linux/mlx4/device.h @@ -427,6 +427,17 @@ 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 (16 bytes) + * - scatter elements (16 bytes each) + */ + MLX4_MAX_SGE_RD = (512 - 16 - 16) / 16 +}; + +enum { MLX4_DEV_PMC_SUBTYPE_GUID_INFO = 0x14, MLX4_DEV_PMC_SUBTYPE_PORT_INFO = 0x15, MLX4_DEV_PMC_SUBTYPE_PKEY_TABLE = 0x16, |