:lines: 1-3,18-
One specifies a name prefix and suffix for each host, and then give an
-integer range. In the example the cluster contains 262145 hosts (!),
-named ``host-0.simgrid.org`` to ``host-262144.simgrid.org``. All hosts
+integer range. In the example the cluster contains 65535 hosts (!),
+named ``node-0.simgrid.org`` to ``node-65534.simgrid.org``. All hosts
have the same power (1 Gflop/sec) and are connected to the switch via
links with same bandwidth (125 MBytes/sec) and latency (50
microseconds).
and ``bb_lat`` attributes that specify the backbone characteristics
(here, a 500 microseconds latency and a 2.25 GByte/sec
bandwidth). This link is used for every communication within the
-cluster. The route from ``node-0.acme.org`` to ``node-1.acme.org``
-counts 3 links: the private link of ``node-0.acme.org``, the backbone
-and the private link of ``node-1.acme.org``.
+cluster. The route from ``node-0.simgrid.org`` to ``node-1.simgrid.org``
+counts 3 links: the private link of ``node-0.simgrid.org``, the backbone
+and the private link of ``node-1.simgrid.org``.
.. todo::
.. code-block:: shell
docker pull simgrid/tuto-smpi
- docker run -it --rm --name simgrid --volume ~/smpi-tutorial:/src/tutorial simgrid/tuto-smpi bash
+ docker run -it --rm --name simgrid --volume ~/smpi-tutorial:/source/tutorial simgrid/tuto-smpi bash
This will start a new container with all you need to take this
tutorial, and create a ``smpi-tutorial`` directory in your home on
-your host machine that will be visible as ``/src/tutorial`` within the
+your host machine that will be visible as ``/source/tutorial`` within the
container. You can then edit the files you want with your favorite
editor in ``~/smpi-tutorial``, and compile them within the
container to enjoy the provided dependencies.
.. warning::
- Any change to the container out of ``/src/tutorial`` will be lost
+ Any change to the container out of ``/source/tutorial`` will be lost
when you log out of the container, so don't edit the other files!
All needed dependencies are already installed in this container
-(SimGrid, a C/C++ compiler, a Fortran compiler, make, pajeng and
-R). Vite being only optional in this tutorial, it is not installed to
-reduce the image size.
+(SimGrid, the C/C++/Fortran compilers, make, pajeng and R). Vite being
+only optional in this tutorial, it is not installed to reduce the
+image size.
-The code template is available under ``/src/simgrid-template-smpi`` in
-the image. You should copy it to your working directory when you first
-log in:
+The container also include the example platform files from the
+previous section as well as the source code of the NAS Parallel
+Benchmarks. These files are available under
+``/source/simgrid-template-smpi`` in the image. You should copy it to
+your working directory when you first log in:
.. code-block:: shell
- cp -r /src/simgrid-template-smpi/* /src/tutorial
- cd /src/tutorial
+ cp -r /source/simgrid-template-smpi/* /source/tutorial
+ cd /source/tutorial
Using your Computer Natively
............................
sudo apt install simgrid pajeng make gcc g++ gfortran vite
-An initial version of the source code is provided on framagit. This
-template compiles with cmake. If SimGrid is correctly installed, you
-should be able to clone the `repository
-<https://framagit.org/simgrid/simgrid-template-smpi>`_ and recompile
-everything as follows:
+To take this tutorial, you will also need the platform files from the
+previous section as well as the source code of the NAS Parallel
+Benchmarks. Just clone `this repository
+<https://framagit.org/simgrid/simgrid-template-smpi>`_ to get them all:
.. code-block:: shell
git clone git@framagit.org:simgrid/simgrid-template-smpi.git
cd simgrid-template-smpi/
- cmake .
- make
If you struggle with the compilation, then you should double check
your :ref:`SimGrid installation <install>`. On need, please refer to
the :ref:`Troubleshooting your Project Setup
<install_yours_troubleshooting>` section.
+Lab 0: Hello World
+------------------
+It is time to simulate your first MPI program. Use the simplistic
+example `roundtrip.c
+<https://framagit.org/simgrid/simgrid-template-smpi/raw/master/roundtrip.c?inline=false>`_
+that comes with the template.
+
+.. literalinclude:: /tuto_smpi/roundtrip.c
+ :language: c
+
+Compiling and Executing
+.......................
+
+Compiling the program is straightforward (double check your
+:ref:`SimGrid installation <install>` if you get an error message):
+
+
+.. code-block:: shell
+
+ $ smpicc -O3 roundtrip.c -o roundtrip
+
+
+Once compiled, you can simulate the execution of this program on 16
+nodes from the ``cluster_crossbar.xml`` platform as follows:
+
+.. code-block:: shell
+
+ $ smpirun -np 16 -platform cluster_crossbar.xml -hostfile cluster_hostfile ./roundtrip
+
+- The ``-np 16`` option, just like in regular MPI, specifies the
+ number of MPI processes to use.
+- The ``-hostfile cluster_hostfile`` option, just like in regular
+ MPI, specifies the host file. If you omit this option, ``smpirun``
+ will deploy the application on the first machines of your platform.
+- The ``-platform cluster_crossbar.xml`` option, **which doesn't exist
+ in regular MPI**, specifies the platform configuration to be
+ simulated.
+- At the end of the line, one finds the executable name and
+ command-line arguments (if any -- roundtrip does not expect any arguments).
+
+Feel free to tweak the content of the XML platform file and the
+prorgam to see the effect on the simulated execution time. Note that
+the simulation accounts for realistic network protocol effects and MPI
+implementation effects. As a result, you may see "unexpected behavior"
+like in the real world (e.g., sending a message 1 byte larger may lead
+to significant higher execution time).
+
+
.. LocalWords: SimGrid
