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authorViacheslav Ovsiienko <viacheslavo@mellanox.com>2019-10-01 06:53:37 +0000
committerFerruh Yigit <ferruh.yigit@intel.com>2019-10-08 12:14:32 +0200
commitb53cd86965a13f0d9efcd7fb02e96bb3f5215916 (patch)
treea4be7502cb61fce7bec463d05a348f2e81be07ac /doc/guides/nics/mlx5.rst
parent97e02581a15bade3f3f943cd16a965a577746006 (diff)
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net/mlx5: adjust inline setting for large Tx queue sizes
The hardware may have limitations on maximal amount of supported Tx descriptors building blocks (WQEBB). Application requires the Tx queue must accept the specified amount of packets. If inline data feature is engaged the packet may require more WQEBBs and overall amount of blocks may exceed the hardware capabilities. Application has to make a trade-off between Tx queue size and maximal data inline size. In case if the inline settings are not requested explicitly with devarg keys the default values are used. This patch adjusts the applied default values if large Tx queue size is requested and default inline settings can not be satisfied due to hardware limitations. The explicitly requested inline setting may be aligned (enlarging only) by configurations routines to provide better WQEBB filling, this implicit alignment is the subject for adjustment either. The warning message is emitted to the log if adjustment happens. Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Diffstat (limited to 'doc/guides/nics/mlx5.rst')
-rw-r--r--doc/guides/nics/mlx5.rst11
1 files changed, 10 insertions, 1 deletions
diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index c2e9003..414c9c1 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -473,6 +473,11 @@ Run-time configuration
The default ``txq_inline_max`` value is 290. The specified value may be adjusted
by the driver in order not to exceed the limit (930 bytes) and to provide better
WQE space filling without gaps, the adjustment is reflected in the debug log.
+ Also, the default value (290) may be decreased in run-time if the large transmit
+ queue size is requested and hardware does not support enough descriptor
+ amount, in this case warning is emitted. If ``txq_inline_max`` key is
+ specified and requested inline settings can not be satisfied then error
+ will be raised.
- ``txq_inline_mpw`` parameter [int]
@@ -494,7 +499,11 @@ Run-time configuration
WQE space filling without gaps, the adjustment is reflected in the debug log.
Due to multiple packets may be included to the same WQE with Enhanced Multi
Packet Write Method and overall WQE size is limited it is not recommended to
- specify large values for the ``txq_inline_mpw``.
+ specify large values for the ``txq_inline_mpw``. Also, the default value (268)
+ may be decreased in run-time if the large transmit queue size is requested
+ and hardware does not support enough descriptor amount, in this case warning
+ is emitted. If ``txq_inline_mpw`` key is specified and requested inline
+ settings can not be satisfied then error will be raised.
- ``txqs_max_vec`` parameter [int]