-/*! @page getting_started SimGrid in 30mn
+/*! @page getting_started Getting Started: SimGrid Main Concepts
-This page does not exist yet. In the meanwhile, please refer to the
-tutorials on the project web page, looking for the "SimGrid User
-101" tutorial.
+@tableofcontents
+
+SimGrid is a framework to simulate distributed computer systems.
+
+It can be used to either assess abstract algorithms, or to profile and
+debug real distributed applications. SimGrid enables studies in the
+domains of (data-)Grids, IaaS Clouds, Clusters, High Performance
+Computing, Volunteer Computing and Peer-to-Peer systems.
+
+Technically speaking, SimGrid is a library. It is neither a graphical
+interface nor a command-line simulator running user scripts. The
+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
+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
+means that SimGrid is developed by a vivid community of users and
+developers. We hope that you will come and join us!
+
+SimGrid is the result of over 15 years of research from several
+groups, both in France and in the USA. It benefited of many funding
+from various research instances, including the ANR, Inria, CNRS,
+University of Lorraine, University of Hawai'i at Manoa, ENS Rennes and
+many others. Many thanks to our generous sponsors!
+
+@section starting_components Typical Study based on SimGrid
+
+Any SimGrid study entails the following components:
+
+ - 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)".
+
+ - The **Virtual Platform**. This is a description of a given
+ distributed system (machines, links, disks, clusters, etc). Most of
+ the platform files are written in XML althrough a Lua interface is
+ under development. SimGrid makes it easy to augment the Virtual
+ 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)".
+
+ - 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)".
+
+ - 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)".
+
+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:
+
+ - **Compare an Application to another**. This is the classical use
+ case for scientists, who use SimGrid to test how the solution that
+ they contribute compares to the existing solutions from the
+ literature.
+
+ - **Design the best Virtual Platform for a given Application.**
+ Tweaking the platform file is much easier than building a new real
+ platform for testing purpose. SimGrid also allows co-design of the
+ platform and the application by modifying both of them.
+
+ - **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.
+
+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
+confident in the results coming out of your simulations. In
+particular, you should not trust blindly your results but always
+strive to double-check them. Likewise, you should question the realism
+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
+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
+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.
+
+@section starting_gears SimGrid Execution Modes
+
+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
+to study how your application behaves on the virtual platform under
+the experimental scenario.
+
+In this mode, SimGrid can provide information about the time taken by
+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
+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
+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
+characteristics, the model-checker will explore the scenario where A
+arrives first, and then rewind to the same point to explore the
+scenario where B arrives first.
+
+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
+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
+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.
+
+A classical trap is that the Model Checker can only verify whether
+your application fits the provided properties, which is useless if you
+have a bug in your property. Remember also that one way for your
+application to never violate a given assert is to not start at all
+because of a stupid bug.
+
+Another limit of this mode is that it does not use the performance
+models of the simulation mode. Time becomes discrete: You can say for
+example that the application took 42 steps to run, but there is no way
+to know the amount of seconds that it took or the amount of watts that
+it dissipated.
+
+Finally, the model checker only explores the interleavings of
+computations and communications. Other factors such as thread
+execution interleaving are not considered by the SimGrid model
+checker.
+
+The model checker may well miss existing issues, as it computes the
+possible outcomes *from a given initial situation*. There is no way to
+prove the correction of your application in all generality with this
+tool.
+
+** **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
+what you are interested in. You are probably looking for a way to run
+each computation kernel only once, save on disk the time it takes and
+some other metadata. This code block can then be skipped in simulation
+and replaced by a synthetic block using the cached information. The
+virtual platform will take this block into account without requesting
+the real hosting machine to benchmark it.
+
+@section starting_limits SimGrid Limits
+
+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
+in this direction), but another framework specifically targeting this
+usecase would probably be more suited.
+
+** **There is currently no support for IoT studies and 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.**
+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
+context.
+
+SimGrid is simply not intended to any study that would mandate the
+abstracted phenomenon. Here are some **studies that you should not do
+with SimGrid**:
+
+ - Studying the effect of L3 vs L2 cache effects on your application
+ - Comparing variantes of TCP
+ - Exploring pathological cases where TCP breaks down, resulting in
+ abnormal executions.
+ - Studying security aspects of your application, in presence of
+ malicious agents.
+
+@section starting_successes SimGrid Success Stories
+
+SimGrid was cited in over 1,500 scientific papers (according to Google
+Scholar). Among them
+<a href="http://simgrid.gforge.inria.fr/Usages.php">over 200
+publications</a> (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.
+This instrument was used in many research communities, such as
+<a href="https://hal.inria.fr/inria-00580599/">High-Performance Computing</a>,
+<a href="http://dx.doi.org/10.1109/CLOUD.2015.125">Cloud Computing</a>,
+<a href="http://dl.acm.org/citation.cfm?id=2310096.2310195">Workflow Scheduling</a>,
+<a href="https://hal.inria.fr/hal-01199200/">Big Data</a> and
+<a href="http://dx.doi.org/10.1109/WSCAD-SSC.2012.18">MapReduce</a>,
+<a href="http://ieeexplore.ieee.org/document/7515695/">Data Grid</a>,
+<a href="http://www.sciencedirect.com/science/article/pii/S1569190X17301028">Volunteer Computing</a>,
+<a href="https://hal.archives-ouvertes.fr/hal-01152469/">Peer-to-Peer Computing</a>,
+<a href="http://dx.doi.org/10.1109/TPDS.2016.2613043">Network Architecture</a>,
+<a href="http://ieeexplore.ieee.org/document/7946412/">Fog Computing</a>, or
+<a href="https://hal.archives-ouvertes.fr/hal-01333471">Batch Scheduling</a>
+<a href="http://simgrid.gforge.inria.fr/Usages.php"><b>(more info)</b></a>.
+
+If your platform description is accurate enough (see
+<a href="http://hal.inria.fr/hal-00907887">here</a> or
+<a href="https://hal.inria.fr/hal-01523608">there</a>),
+SimGrid can provide high-quality performance predictions. For example,
+we determined the speedup achieved by the Tibidabo Arm-based
+cluster before its construction
+(<a href="http://hal.inria.fr/hal-00919507">paper</a>). In this case,
+some differences between the prediction and the real timings were due to
+misconfiguration or other problems with the real platforms. To some extent,
+SimGrid could even be used to debug the real platform :)
+
+SimGrid is also used to debug, improve and tune several large
+applications.
+<a href="http://bigdft.org">BigDFT</a> (a massively parallel code
+computing the electronic structure of chemical elements developped by
+the CEA), <a href="http://starpu.gforge.inria.fr/">StarPU</a> (a
+Unified Runtime System for Heterogeneous Multicore Architectures
+developped by Inria Bordeaux) and
+<a href="https://tomp2p.net/dev/simgrid/">TomP2P</a> (a high performance
+key-value pair storage library developped at University of Zurich).
+Some of these applications enjoy large user communities themselves.
+
+@section starting_next 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 "install it". Then,
+proceed to the section on @ref application "describing the application" that
+you want to study.
*/
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