[PATCH v9 17/17] doc: update multicore dispatch model in graph guides

[Yan, Zhirun]

> -----Original Message-----
> From: Jerin Jacob <jerinjacobk at gmail.com>
> Sent: Wednesday, June 7, 2023 8:46 PM
> To: Yan, Zhirun <zhirun.yan at intel.com>
> Cc: dev at dpdk.org; jerinj at marvell.com; kirankumark at marvell.com;
> ndabilpuram at marvell.com; stephen at networkplumber.org;
> pbhagavatula at marvell.com; Liang, Cunming <cunming.liang at intel.com>; Wang,
> Haiyue <haiyue.wang at intel.com>; mattias.ronnblom
> <mattias.ronnblom at ericsson.com>
> Subject: Re: [PATCH v9 17/17] doc: update multicore dispatch model in graph
> guides
> 
> On Wed, Jun 7, 2023 at 9:30 AM Zhirun Yan <zhirun.yan at intel.com> wrote:
> >
> > Update graph documentation to introduce new multicore dispatch model.
> 
> Please squash this to relevant implementation patches, No need for separate
> patch. This is the contribution guideline followed.
> 
Got it. I will squash this to the patch of walk model choosing in patch 13.
> >
> > Signed-off-by: Haiyue Wang <haiyue.wang at intel.com>
> > Signed-off-by: Cunming Liang <cunming.liang at intel.com>
> > Signed-off-by: Zhirun Yan <zhirun.yan at intel.com>
> > ---
> >  doc/guides/prog_guide/graph_lib.rst | 68
> > +++++++++++++++++++++++++++--
> >  1 file changed, 64 insertions(+), 4 deletions(-)
> >
> > diff --git a/doc/guides/prog_guide/graph_lib.rst
> > b/doc/guides/prog_guide/graph_lib.rst
> > index 1cfdc86433..8c2c2816ed 100644
> > --- a/doc/guides/prog_guide/graph_lib.rst
> > +++ b/doc/guides/prog_guide/graph_lib.rst
> > @@ -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
> 
> Graph models
> 
> > +~~~~~~~~~~~~~~~~~~~~~
> > +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
> 
> by not defining RTE_GRAPH_MODEL_SELECT.
> 
> > +For application, must #define RTE_GRAPH_MODEL_SELECT before including
> > +rte_graph_worker.h
> 
> Some rewording as suggestion.
> 
> Graph models
> ~~~~~~~~~~~~
> There are two different kinds of graph walking models. User can select the
> model using ``rte_graph_worker_model_set()`` API. If the application decides to
> use only one model,  the fast path check can be avoided by defining the model
> with RTE_GRAPH_MODEL_SELECT. For example:
> 
> .. code-block:: console
> 
> #define RTE_GRAPH_MODEL_SELECT RTE_GRAPH_MODEL_RTC #include
> "rte_graph_worker.h"
> 
> 

Thanks for your refine. I will update in next version.

> 
> > +
> > +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.
> 
> Please move to doc/guides/sample_app_ug/l3_forward_graph.rst
> 
Yes, will move it  and squash this part into example patch.

> > +
> > +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
> > --
> > 2.37.2
> >