[dpdk-dev] [PATCH] net/mlx5: document workaround for ConnectX-4 with L2 encap
From: Dmitry Kozlyuk <hidden>
Date: 2021-06-30 07:01:40
Subsystem:
the rest · Maintainer:
Linus Torvalds
ConnectX-4 and ConnectX-4 Lx NICs require all L2 headers of transmitted
packets to be inlined. By default only first 18 bytes are inlined,
which is insufficient if additional encapsulation is used, like Q-in-Q.
Thus, default settings caused such traffic to be dropepd on Tx.
Document a workaround to increase inlined data size in such cases.
Fixes: 505f1fe426d3 ("net/mlx5: add Tx devargs")
Cc: stable@dpdk.org
Signed-off-by: Dmitry Kozlyuk <redacted>
Reviewed-by: Viacheslav Ovsiienko <redacted>
---
doc/guides/nics/mlx5.rst | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index ebefbe607e..05a89d08f2 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst@@ -705,6 +705,13 @@ Driver options it is not recommended and may prevent NIC from sending packets over some configurations. + For ConnectX-4 and ConnectX-4 Lx NICs, automatically configured value + is insufficient for some traffic, because they require at least all L2 headers + to be inlined. For example, Q-in-Q adds 4 bytes to default 18 bytes + of Ethernet and VLAN, thus ``txq_inline_min`` must be set to 22. + MPLS would add 4 bytes per label. Final value must account for all possible + L2 encapsulation headers used in particular environment. + Please, note, this minimal data inlining disengages eMPW feature (Enhanced Multi-Packet Write), because last one does not support partial packet inlining. This is not very critical due to minimal data inlining is mostly required
--
2.25.1