add svg and some description for dragonfly topology

[simgrid.git] / docs / source / tuto_smpi.rst

diff --git a/docs/source/tuto_smpi.rst b/docs/source/tuto_smpi.rst
index 12da31b..bb16ec6 100644 (file)
--- a/docs/source/tuto_smpi.rst
+++ b/docs/source/tuto_smpi.rst
@@ -54,7 +54,7 @@ To start using SMPI, you just need to compile your application with
 ``mpiff``, or with ``smpicxx`` instead of ``mpicxx``. Then, the only
 difference between the classical ``mpirun`` and the new ``smpirun`` is
 that it requires a new parameter ``-platform`` with a file describing
-the virtual platform on which your application shall run.
+the simulated platform on which your application shall run.
 
 Internally, all ranks of your application are executed as threads of a
 single unix process. That's not a problem if your application has
@@ -73,7 +73,7 @@ Describing Your Platform
 ------------------------
 
 As a SMPI user, you are supposed to provide a description of your
-virtual platform, that is mostly a set of simulated hosts and network
+simulated platform, that is mostly a set of simulated hosts and network
 links with some performance characteristics. SimGrid provides a plenty
 of :ref:`documentation <platform>` and examples (in the
 `examples/platforms <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms>`_
@@ -214,14 +214,28 @@ Dragonfly Cluster
 This topology was introduced to further reduce the amount of links
 while maintaining a high bandwidth for local communications. To model
 this in SimGrid, pass a ``topology="DRAGONFLY"`` attribute to your
-cluster.
+cluster. It's based on the implementation of the topology used on 
+Cray XC systems, described in paper
+``Cray Cascade: A scalable HPC system based on a Dragonfly network`` :
 
-.. literalinclude:: ../../examples/platforms/cluster_dragonfly.xml
-   :language: xml
+System description follows the format ``topo_parameters=#groups;#chassis;#routers;#nodes``
 
-.. todo::
+For example, ``3,4 ; 3,2 ; 3,1 ; 2``:
+
+- ``3,4``: There are 3 groups with 4 links between each (blue level).
+  Links to nth group are attached to the nth router of the group 
+  on our implementation.
+- ``3,2``: In each group, there are 3 chassis with 2 links between each nth router
+  of each group (black level)
+- ``3,1``: In each chassis, 3 routers are connected together with a single link
+  (green level)
+- ``2``: Each router has two nodes attached (single link) 
 
-   Add the image, and the documuentation of the topo_parameters.
+.. image:: ../../examples/platforms/cluster_dragonfly.svg
+   :align: center
+
+.. literalinclude:: ../../examples/platforms/cluster_dragonfly.xml
+   :language: xml
 
 Final Word
 ..........