diff options
| author | Sagi Grimberg <sagi@grimberg.me> | 2016-03-31 19:03:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-05-04 14:48:48 -0700 |
| commit | 29ebbba744cf8951202b5f4ea62b4a297f4662c1 (patch) | |
| tree | 402f698f00bef77f2a4080c591e3646cd6419c0b /include | |
| parent | b184522f688a31765a24081ed231e480e76edae6 (diff) | |
IB/mlx5: Expose correct max_sge_rd limit
commit 986ef95ecdd3eb6fa29433e68faa94c7624083be upstream.
mlx5 devices (Connect-IB, ConnectX-4, ConnectX-4-LX) 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.
Reported-by: Christoph Hellwig <hch@lst.de>
Tested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagig@grimberg.me>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mlx5/device.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/mlx5/device.h b/include/linux/mlx5/device.h index 0b473cbfa7ef..a91b67b18a73 100644 --- a/include/linux/mlx5/device.h +++ b/include/linux/mlx5/device.h @@ -334,6 +334,17 @@ enum { MLX5_CAP_OFF_CMDIF_CSUM = 46, }; +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) + */ + MLX5_MAX_SGE_RD = (512 - 16 - 16) / 16 +}; + struct mlx5_inbox_hdr { __be16 opcode; u8 rsvd[4]; |