X-Git-Url: http://bilbo.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/9f159d9330c05815626203388772dc0cfa5a1575..8b89dfa40fa9b2f1a4a5bff7d8efe38d302d120b:/docs/source/tuto_smpi.rst

diff --git a/docs/source/tuto_smpi.rst b/docs/source/tuto_smpi.rst
index 3b26c93eb3..17eec10f96 100644
--- a/docs/source/tuto_smpi.rst
+++ b/docs/source/tuto_smpi.rst
@@ -29,9 +29,9 @@ use SimGrid for their integration and performance testing.
 
 MPI 2.2 is already partially covered: over 160 primitives are
 supported. Some parts of the standard are still missing: MPI-IO, MPI3
-collectives, spawning ranks, and some others. If one of the functions
-you use is still missing, please drop us an email. We may find the
-time to implement it for you.
+collectives, spawning ranks, inter-communicators, and some others. If
+one of the functions you use is still missing, please drop us an
+email. We may find the time to implement it for you.
 
 Multi-threading support is very limited in SMPI. Only funneled
 applications are supported: at most one thread per rank can issue any
@@ -214,15 +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 <https://dl.acm.org/citation.cfm?id=2389136>`_.
+
+System description follows the format ``topo_parameters=#groups;#chassis;#routers;#nodes``
+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) 
+
+.. image:: ../../examples/platforms/cluster_dragonfly.svg
+   :align: center
 
 .. literalinclude:: ../../examples/platforms/cluster_dragonfly.xml
    :language: xml
 
-.. todo::
-
-   Add the image, and the documuentation of the topo_parameters.
-
 Final Word
 ..........