[v4] doc: add information for Rx burst functions in mlx5
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Commit Message
mlx5 pmd supports various rx_burst functions.
Each function is enabled differently and supports different features.
Add more comprehensive information about each function.
Signed-off-by: Asaf Penso <asafp@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
v4: update the fallback for mprq burst functions
v3: checkpatch cleanup
v2: for mprq added note for rxqs_min_mprq
---
doc/guides/nics/mlx5.rst | 59 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
@@ -1645,3 +1645,62 @@ all flows with assistance of external tools.
.. code-block:: console
mlx_steering_dump.py -f <output_file>
+
+RX burst functions
+------------------
+
+This section describes the different rx_burst functions and provides an
+elaborated information.
+
+#. Function name - rx_burst
+ How to enable - rx_vec_en=0
+ Scatter support - Yes
+ RX error recovery support - Yes
+ CQE compression support - Yes
+ Large MTU support - The maximal packet size should be set to be the
+ same as the MTU size. The mbuf size can be
+ according to the application needs since the
+ pmd can perform the scatter.
+
+#. Function name - rx_burst_vec
+ How to enable - rx_vec_en=1 (default value)
+ Scatter support - No
+ RX error recovery support - Supported only in case CQE compression is off
+ CQE compression support - Yes
+ Large MTU support - No. Scatter is not supported, so it means
+ that the mbuf must be with the same size of
+ the MTU. In this case, maximal packet size ==
+ mbuf size == MTU size
+ Fallback - In scatter or LRO fallback to rx_burst
+ Notes - Improves CPU utilization for single-core and
+ improves performance
+
+#. Function name - rx_burst_mprq
+ How to enable - mprq_en=1
+ - RX queues number should be >= rxqs_min_mprq
+ Scatter support - No
+ RX error recovery support - Yes
+ CQE compression support - Yes
+ Large MTU support - Yes. Needs to be turned on by specifying the
+ stride size
+ Fallback - In scatter fallback to rx_burst
+ Notes - Saving PCI bandwidth and getting higher
+ performance, especially for small packets.
+ Used mainly for multi-core use cases.
+ Uses externally attached buffers only.
+
+#. Function name - rx_burst_mprq_vec
+ How to enable - rx_vec_en=1 (default mode) and mprq_en=1
+ - RX queues number should be >= rxqs_min_mprq
+ Scatter support - No
+ RX error recovery support - Supported only in case CQE compression is off
+ CQE compression support - Yes
+ Large MTU support - Yes. Needs to be turned on by specifying the
+ stride size
+ Fallback - In scatter fallback to rx_burst.
+ In LRO fallback to rx_burst_mprq.
+ Notes - Improves CPU utilization of regular
+ rx_burst_mprq for multi-core and improves
+ performance.
+ Used mainly for multi-core use cases.
+ Uses externally attached buffers only.