interaction with SimGrid is done by writing programs with the exposed
functions to build your own simulator.
-SimGrid offers many features, many options and many possibilities. The
-documentation aims at smoothing the learning curve. But nothing's
-perfect, and this documentation is really no exception here. Please
-help us improving it by reporting any issue that you see and
-proposing the content that is still missing.
-
-SimGrid is a Free Software distributed under the LGPL licence. You are
+SimGrid is a Free Software distributed under the LGPL license. You are
thus welcome to use it as you wish, or even to modify and distribute
-your version (as long as your version is as free as ours). It also
+your version (provided that your version is as free as ours). It also
means that SimGrid is developed by a vivid community of users and
developers. We hope that you will come and join us!
University of Lorraine, University of Hawai'i at Manoa, ENS Rennes and
many others. Many thanks to our generous sponsors!
+SimGrid is a powerful tool, but its learning curve can be rather
+steep. This manual will hopefully help and guide you to the features
+you want to use. Please report any issue that you see in this manual,
+including typos or unclear elements. You can even propose changes by
+clicking on the "Edit on GitLab" button at the top of every page.
+
Typical Study based on SimGrid
------------------------------
- The studied **Application**. This can be either a distributed
algorithm described in our simple APIs, or a full featured real
parallel application using for example the MPI interface
- @ref application "(more info)".
+ :ref:`(more info) <application>`.
- The **Virtual Platform**. This is a description of a given
distributed system (machines, links, disks, clusters, etc). Most of
Platform with a Dynamic Scenario where for example the links are
slowed down (because of external usage), the machines fail. You
have even support to specify the applicative workload that you want
- to feed to your application @ref platform "(more info)".
+ to feed to your application
+ :ref:`(more info) <platform>`.
- The application's **Deployment Description**. In SimGrid
terminology, the application is an inert set of source files and
binaries. To make it run, you have to describe how your application
should be deployed on the virtual platform. You need to specify
which process is mapped on which host, along with their parameters
- @ref deployment "(more info)".
+ :ref:`(more info) <scenario>`.
- The **Platform Models**. They describe how the virtual platform
reacts to the actions of the application. For example, they compute
the time taken by a given communication on the virtual platform.
These models are already included in SimGrid, and you only need to
pick one and maybe tweak its configuration to get your results
- @ref models "(more info)".
+ :ref:`(more info) <models>`.
These components are put together to run a **simulation**, that is an
experiment or a probe. The result of one or many simulation provides
an **outcome** (logs, visualization, statistical analysis) that help
answering the **question** targeted by this study.
-The questions that SimGrid can solve include the following:
+Here are some questions on which SimGrid is particularly relevant:
- **Compare an Application to another**. This is the classical use
case for scientists, who use SimGrid to test how the solution that
- **Debug Real Applications**. With real systems, is sometimes
difficult to reproduce the exact run leading to the bug that you
- are tracking. SimGrid gives you experimental reproducibility,
- clairevoyance (you can explore every part of the system, and your
- probe will not change the simulated state). It also makes it easy
- to mock some parts of the real system that are not under study.
+ are tracking. With SimGrid, you are *clairvoyant* about your
+ *reproducible experiments*: you can explore every part of the
+ system, and your probe will not change the simulated state. It also
+ makes it easy to mock some parts of the real system that are not
+ under study.
Depending on the context, you may see some parts of this process as
less important, but you should pay close attention if you want to be
of your input configuration, and we even encourage you to doubt (and
check) the provided performance models.
-To ease such questionning, you really should logically separate these
+To ease such questioning, you really should logically separate these
parts in your experimental setup. It is seen as a very bad practice to
merge the application, the platform and the deployment all together.
-SimGrid is versatile and your milleage may vary, but you should start
+SimGrid is versatile and your mileage may vary, but you should start
with your Application specified as a C++ or Java program, using one of
the provided XML platform file, and with your deployment in a separate
XML file.
Depending on the intended study, SimGrid can be run in several execution modes.
-** **Simulation Mode**. This is the most common execution mode, where you want
+**Simulation Mode**. This is the most common execution mode, where you want
to study how your application behaves on the virtual platform under
the experimental scenario.
your application, the amount of energy dissipated by the platform to
run your application and the detailed usage of each resource.
-** **Model-Checking Mode**. This can be seen as a sort of exhaustive
+**Model-Checking Mode**. This can be seen as a sort of exhaustive
testing mode, where every possible outcome of your application is
explored. In some sense, this mode tests your application for all
possible platforms that you could imagine (and more).
You just provide the application and its deployment (amount of
-processes and parameters), and the model-checker will litterally
+processes and parameters), and the model-checker will literally
explore all possible outcomes by testing all possible message
interleavings: if at some point a given process can either receive the
message A first or the message B depending on the platform
This is a very powerful mode, where you can evaluate the correction of
your application. It can verify either **safety properties** (asserts)
or **liveless properties** stating for example that if a given event
-occures, then another given event will occur in a finite amount of
+occurs, then another given event will occur in a finite amount of
steps. This mode is not only usable with the abstract algorithms
developed on top of the SimGrid APIs, but also with real MPI
applications (to some extend).
The main limit of Model Checking lays in the huge amount of scenarios
-to explore. SimGrid tries to explore only non-redundent scenarios
+to explore. SimGrid tries to explore only non-redundant scenarios
thanks to classical reduction techniques (such as DPOR and stateful
exploration) but the exploration may well never finish if you don't
carefully adapt your application to this mode.
prove the correction of your application in all generality with this
tool.
-** **Benchmark Recording Mode**. During debug sessions, continuous
+**Benchmark Recording Mode**. During debug sessions, continuous
integration testing and other similar use cases, you are often only
interested in the control flow. If your application apply filters to
huge images split in small blocks, the filtered image is probably not
This framework is by no means the perfect holly grail able to solve
every problem on earth.
-** **SimGrid scope is limited to distributed systems.** Real-time
-multithreaded systems are not in the scope. You could probably tweak
-SimGrid for such studies (or the framework could possibily be extended
+**SimGrid scope is limited to distributed systems.** Real-time
+multi-threaded systems are not in the scope. You could probably tweak
+SimGrid for such studies (or the framework could possibly be extended
in this direction), but another framework specifically targeting this
-usecase would probably be more suited.
+use case would probably be more suited.
-** **There is currently no support for IoT studies and wireless networks**.
+**There is currently no support for wireless networks**.
The framework could certainly be improved in this direction, but this
is still to be done.
-** **There is no perfect model, only models adapted to your study.**
+**There is no perfect model, only models adapted to your study.**
The SimGrid models target fast, large studies yet requesting a
realistic results. In particular, our models abstract away parameters
and phenomenon that are often irrelevant to the realism in our
with SimGrid**:
- Studying the effect of L3 vs L2 cache effects on your application
- - Comparing variantes of TCP
+ - Comparing kernel schedulers and policies
+ - Comparing variants of TCP
- Exploring pathological cases where TCP breaks down, resulting in
abnormal executions.
- Studying security aspects of your application, in presence of
SimGrid was cited in over 1,500 scientific papers (according to Google
Scholar). Among them
-`over 200 publications <http://simgrid.gforge.inria.fr/Usages.php>`_
+`over 200 publications <https://simgrid.org/Usages.html>`_
(written by about 300 individuals) use SimGrid as a scientific
instrument to conduct their experimental evaluation. These
numbers do not count the articles contributing to SimGrid.
`Network Architecture <http://dx.doi.org/10.1109/TPDS.2016.2613043>`_,
`Fog Computing <http://ieeexplore.ieee.org/document/7946412/>`_, or
`Batch Scheduling <https://hal.archives-ouvertes.fr/hal-01333471>`_
-`(more info) <http://simgrid.gforge.inria.fr/Usages.php>`_.
+`(more info) <https://simgrid.org/Usages.html>`_.
If your platform description is accurate enough (see
`here <http://hal.inria.fr/hal-00907887>`_ or
Unified Runtime System for Heterogeneous Multicore Architectures
developped by Inria Bordeaux) and
`TomP2P <https://tomp2p.net/dev/simgrid/>`_ (a high performance
-key-value pair storage library developped at University of Zurich).
+key-value pair storage library developed at University of Zurich).
Some of these applications enjoy large user communities themselves.
-Where to proceed next?
-----------------------
-
-Now that you know about the basic concepts of SimGrid, you can give it
-a try. If it's not done yet, first :ref:`install it <install>`. Then,
-proceed to the section on @ref application "describing the application" that
-you want to study.
+.. LocalWords: SimGrid
