-
-This programming environment permits to study existing MPI application
-by emulating them on top of the SimGrid simulator. In other words, it
-will constitute an emulation solution for parallel codes. You don't
-even have to modify your code for that, although that may help, as
-detailed below.
-
-\section SMPI_who Who should use SMPI (and who shouldn't)
-
-You should use this programming environment of the SimGrid suite if
-you want to study existing MPI applications. If you want to study
-some heuristics for a given problem (and if your goal is to produce
-theorems and publications, not code), have a look at the \ref MSG_API
-environment, or the \ref SD_API one if you need to use DAGs. If none
-of those programming environments fits your needs, you may consider
-implementing your own directly on top of \ref SURF_API (but you
-probably want to contact us before).
-
-\section SMPI_what What can run within SMPI?
-
-You can run unmodified MPI applications (both C and Fortran) within
-SMPI, provided you only use MPI calls that we implemented in MPI. Our
-coverage of the interface is not bad, but will probably never be
-complete. One sided communications and I/O primitives are not targeted
-for now. The full list of not yet implemented functions is available
-in file <tt>include/smpi/smpi.h</tt> of the archive, between two lines
-containing the <tt>FIXME</tt> marker. If you really need a missing
-feature, please get in touch with us: we can guide you though the
-SimGrid code to help you implementing it, and we'd glad to integrate
-it in the main project afterward if you contribute them back.
-
-\section SMPI_adapting Adapting your MPI code to the use of SMPI
-
-As detailed in the reference article (available at
-http://hal.inria.fr/inria-00527150), you may want to adapt your code
-to improve the simulation performance. But these tricks may seriously
-hinder the result qualtity (or even prevent the app to run) if used
-wrongly. We assume that if you want to simulate an HPC application,
-you know what you are doing. Don't prove us wrong!
-
-If you get short on memory (the whole app is executed on a single node
-when simulated), you should have a look at the SMPI_SHARED_MALLOC and
-SMPI_SHARED_FREE macros. It allows to share memory areas between
-processes. For example, matrix multiplication code may want to store
-the blocks on the same area. Of course, the resulting computations
-will useless, but you can still study the application behavior this
-way. Of course, if your code is data-dependent, this won't work.
-
-If your application is too slow, try using SMPI_SAMPLE_LOCAL,
-SMPI_SAMPLE_GLOBAL and friends to indicate which computation loops can
-be sampled. Some of the loop iterations will be executed to measure
-their duration, and this duration will be used for the subsequent
-iterations. These samples are done per processor with
-SMPI_SAMPLE_LOCAL, and shared between all processors with
-SMPI_SAMPLE_GLOBAL. Of course, none of this will work if the execution
-time of your loop iteration are not stable.
-
-Yes, that's right, these macros are not documented yet, but we'll fix
-it as soon as time permits. Sorry about that -- patch welcomed!
-Meanwhile, grep for them on the examples for more information.
-
-\section SMPI_compiling Compiling your code
-
-This is very simply done with the <tt>smpicc</tt> script. If you
-already compiled any MPI code before, you already know how to use it.
-If not, you should try to get your MPI code running on top of MPI
-before giving SMPI a spin. Actually, that's very simple even if it's
-the first time you use MPI code: just use smpicc as a compiler (in
-replacement of gcc or your usual compiler), and you're set.
-
-\section SMPI_executing Executing your code on top of the simulator
-
-This is done though the <tt>smpirun</tt> script as follows.
-<tt>my_hostfile.txt</tt> is a classical MPI hostfile (that is, this
-file lists the machines on which the processes must be dispatched, one
-per line) <tt>my_platform.xml</tt> is a classical SimGrid platform
-file. Of course, the hosts of the hostfile must exist in the provided
-platform. <tt>./program</tt> is the MPI program that you want to
-simulate (must be compiled by <tt>smpicc</tt>) while <tt>-arg</tt> is
-a command-line parameter passed to this program.
-
-\verbatim
-smpirun -hostfile my_hostfile.txt -platform my_platform.xml ./program -arg
-\endverbatim
-
-smpirun accepts other parameters, such as <tt>-np</tt> if you don't
-want to use all the hosts defined in the hostfile, <tt>-map</tt> to
-display on which host each rank gets mapped of <tt>-trace</tt> to
-activate the tracing during the simulation. You can get the full list
-by running
-\verbatim
-smpirun -help
-\endverbatim
-
-
