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authorSagi Grimberg <sagig@mellanox.com>2015-10-28 13:28:15 +0200
committerDoug Ledford <dledford@redhat.com>2015-12-08 12:42:44 -0500
commita5e14ba334e202c58e45ef47414ec94c585c1a8c (patch)
treeb04bac58103e9551d2107aa96295db010c5695a2 /include
parent533708867dd6388f643f12c87465b59e732d729d (diff)
downloadleg-kernel-a5e14ba334e202c58e45ef47414ec94c585c1a8c.tar.gz
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')
-rw-r--r--include/linux/mlx4/device.h11
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,