fix sectionning and one typo

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

diff --git a/docs/source/tuto_smpi.rst b/docs/source/tuto_smpi.rst
index 082bbb1..4599f92 100644 (file)
--- a/docs/source/tuto_smpi.rst
+++ b/docs/source/tuto_smpi.rst
@@ -37,7 +37,7 @@ only plan to debug your application in a reproducible setup, without
 any performance-related analysis.
 
 How does it work?
 any performance-related analysis.
 
 How does it work?

------------------
+^^^^^^^^^^^^^^^^^

 
 In SMPI, communications are simulated while computations are
 emulated. This means that while computations occur as they would in
 
 In SMPI, communications are simulated while computations are
 emulated. This means that while computations occur as they would in


@@ -61,7 +61,54 @@ to predict the time taken by each communications. Any computations
 occuring between two MPI calls are benchmarked, and the corresponding
 time is reported into the simulator.
 
 occuring between two MPI calls are benchmarked, and the corresponding
 time is reported into the simulator.
 

+.. image:: /tuto_smpi/img/big-picture.png
+   :align: center
+
+

 Describing Your Platform
 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
+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>`_
+source directory), and this section only shows a small set of introductory
+examples.
+
+Simple Example with 3 hosts
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+At the most basic level, you can describe your simulated platform as a
+graph of hosts and network links. For instance:
+
+.. image:: /tuto_smpi/img/3hosts.png
+   :align: center
+
+.. hidden-code-block:: xml
+    :starthidden: True
+    :label: See the XML platform description file...
+
+    <?xml version='1.0'?>
+    <!DOCTYPE platform SYSTEM "http://simgrid.gforge.inria.fr/simgrid/simgrid.dtd">
+    <platform version="4.1">
+      <zone id="AS0" routing="Full">
+        <host id="host0" speed="1Gf"/>
+        <host id="host1" speed="2Gf"/>
+        <host id="host2" speed="40Gf"/>
+        <link id="link0" bandwidth="125MBps" latency="100us"/>
+        <link id="link1" bandwidth="50MBps" latency="150us"/>
+        <link id="link2" bandwidth="250MBps" latency="50us"/>
+        <route src="host0" dst="host1"><link_ctn id="link0"/><link_ctn id="link1"/></route>
+        <route src="host1" dst="host2"><link_ctn id="link1"/><link_ctn id="link2"/></route>
+        <route src="host0" dst="host2"><link_ctn id="link0"/><link_ctn id="link2"/></route>
+      </zone>
+    </platform>

 
 

+In this XML, note the way in which hosts, links, and routes are
+defined. All hosts are defined with a power (i.e., compute speed in
+Gflops), and links with a latency (in us) and bandwidth (in MBytes per
+second). Other units are possible and written as expected. By default,
+routes are symmetrical.
+       

 ..  LocalWords:  SimGrid
 ..  LocalWords:  SimGrid