[v8,17/17] doc: update multicore dispatch model in graph guides
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Commit Message
Update graph documentation to introduce new multicore dispatch model.
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Signed-off-by: Cunming Liang <cunming.liang@intel.com>
Signed-off-by: Zhirun Yan <zhirun.yan@intel.com>
---
doc/guides/prog_guide/graph_lib.rst | 68 +++++++++++++++++++++++++++--
1 file changed, 64 insertions(+), 4 deletions(-)
@@ -189,14 +189,74 @@ In the above example, A graph object will be created with ethdev Rx
node of port 0 and queue 0, all ipv4* nodes in the system,
and ethdev tx node of all ports.
-Multicore graph processing
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-In the current graph library implementation, specifically,
-``rte_graph_walk()`` and ``rte_node_enqueue*`` fast path API functions
+Graph models chossing
+~~~~~~~~~~~~~~~~~~~~~
+Currently, there are 2 different walking models. Use macro
+RTE_GRAPH_MODEL_SELECT to set the model in compile time. Also offers the
+ability to choose models in runtime.
+For application, must #define RTE_GRAPH_MODEL_SELECT before inlcuding
+rte_graph_worker.h.
+
+In l3fwd-graph, set RTE_GRAPH_MODEL_SELECT as the model explicitly for
+performance-sensitive use case.
+Or set the macro as GRAPH_MODEL_MCORE_RUNTIME_SELECT. And parse
+``"--model=NAME"`` in cmdline and use ``rte_graph_worker_model_set()``
+to set the walking model in runtime.
+
+RTC (Run-To-Completion)
+^^^^^^^^^^^^^^^^^^^^^^^
+This is the default graph walking model. Specifically,
+``rte_graph_walk_rtc()`` and ``rte_node_enqueue*`` fast path API functions
are designed to work on single-core to have better performance.
The fast path API works on graph object, So the multi-core graph
processing strategy would be to create graph object PER WORKER.
+Example:
+
+Graph: node-0 -> node-1 -> node-2 @Core0.
+
+.. code-block:: diff
+
+ + - - - - - - - - - - - - - - - - - - - - - +
+ ' Core #0 '
+ ' '
+ ' +--------+ +---------+ +--------+ '
+ ' | Node-0 | --> | Node-1 | --> | Node-2 | '
+ ' +--------+ +---------+ +--------+ '
+ ' '
+ + - - - - - - - - - - - - - - - - - - - - - +
+
+Dispatch model
+^^^^^^^^^^^^^^
+The dispatch model enables a cross-core dispatching mechanism which employs
+a scheduling work-queue to dispatch streams to other worker cores which
+being associated with the destination node.
+
+Use ``rte_graph_model_mcore_dispatch_lcore_affinity_set()`` to set lcore affinity
+with the node.
+Each worker core will have a graph repetition. Use ``rte_graph_clone()`` to clone
+graph for each worker and use``rte_graph_model_mcore_dispatch_core_bind()`` to
+bind graph with the worker core.
+
+Example:
+
+Graph topo: node-0 -> Core1; node-1 -> node-2; node-2 -> node-3.
+Config graph: node-0 @Core0; node-1/3 @Core1; node-2 @Core2.
+
+.. code-block:: diff
+
+ + - - - - - -+ +- - - - - - - - - - - - - + + - - - - - -+
+ ' Core #0 ' ' Core #1 ' ' Core #2 '
+ ' ' ' ' ' '
+ ' +--------+ ' ' +--------+ +--------+ ' ' +--------+ '
+ ' | Node-0 | - - - ->| Node-1 | | Node-3 |<- - - - | Node-2 | '
+ ' +--------+ ' ' +--------+ +--------+ ' ' +--------+ '
+ ' ' ' | ' ' ^ '
+ + - - - - - -+ +- - -|- - - - - - - - - - + + - - -|- - -+
+ | |
+ + - - - - - - - - - - - - - - - - +
+
+
In fast path
~~~~~~~~~~~~
Typical fast-path code looks like below, where the application