path: root/doc/guides/nics/mlx5.rst
diff options
authorShahaf Shuler <>2018-08-13 09:47:57 +0300
committerFerruh Yigit <>2018-08-28 15:27:39 +0200
commitf9de87187b7f233cc5b1ea964c05311dfeed951a (patch)
tree226887ff8ad6b113234dbd705dffb16960e55e9c /doc/guides/nics/mlx5.rst
parentdce1e4c2044d0e197eee29182cdb93454a0dc3d5 (diff)
net/mlx5: disable ConnectX-4 Lx Multi Packet Send by default
On ConnectX-4 Lx the Multi Packet Send (MPW) feature is considered un-secure, as on some cases were the application provides incorrect mbufs on the Tx burst the host or NIC can get stuck. Hence, disabling the feature by default for this specific NIC. Users can still enable this feature and enjoy the performance gain (mostly for low number of cores) by using the txq_mpw_en devarg. This patch will impact the out of the box performance of some application using ConnectX-4 Lx for the sack of security and robustness. Since we need different defaults based on the underlying device the mpw field in the configuration struct was extended to contain also the MLX5_ARG_UNSET option. Cc: Signed-off-by: Shahaf Shuler <> Acked-by: Yongseok Koh <>
Diffstat (limited to 'doc/guides/nics/mlx5.rst')
1 files changed, 6 insertions, 1 deletions
diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 52e1213..dbdb90b 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -339,7 +339,12 @@ Run-time configuration
When those offloads are requested the MPS send function will not be used.
It is currently only supported on the ConnectX-4 Lx, ConnectX-5 and Bluefield
- families of adapters. Enabled by default.
+ families of adapters.
+ On ConnectX-4 Lx the MPW is considered un-secure hence disabled by default.
+ Users which enable the MPW should be aware that application which provides incorrect
+ mbuf descriptors in the Tx burst can lead to serious errors in the host including, on some cases,
+ NIC to get stuck.
+ On ConnectX-5 and Bluefield the MPW is secure and enabled by default.
- ``txq_mpw_hdr_dseg_en`` parameter [int]