316 research outputs found
Applying Formal Methods to Networking: Theory, Techniques and Applications
Despite its great importance, modern network infrastructure is remarkable for
the lack of rigor in its engineering. The Internet which began as a research
experiment was never designed to handle the users and applications it hosts
today. The lack of formalization of the Internet architecture meant limited
abstractions and modularity, especially for the control and management planes,
thus requiring for every new need a new protocol built from scratch. This led
to an unwieldy ossified Internet architecture resistant to any attempts at
formal verification, and an Internet culture where expediency and pragmatism
are favored over formal correctness. Fortunately, recent work in the space of
clean slate Internet design---especially, the software defined networking (SDN)
paradigm---offers the Internet community another chance to develop the right
kind of architecture and abstractions. This has also led to a great resurgence
in interest of applying formal methods to specification, verification, and
synthesis of networking protocols and applications. In this paper, we present a
self-contained tutorial of the formidable amount of work that has been done in
formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial
Compositional circuit design with asynchronous concepts
PhD ThesisSynchronous circuits are pervasive in modern digital systems, such as smart-phones,
wearable devices and computers. Synchronous circuits are controlled by a global clock
signal, which greatly simplifies their design but is also a limitation in some applications.
Asynchronous circuits are a logical alternative: they do not use a global clock to synchronise
their components. Instead, every component reacts to input events at the rate
they occur. Asynchronous circuits are not widely adopted by industry, because they are
often harder to design and require more sophisticated tools and formal models.
Signal Transition Graphs (STGs) is a well-studied formal model for the specification,
verification and synthesis of asynchronous circuits with state-of-the-art tool support.
STGs use a graphical notation where vertices and arcs specify the operation of
an asynchronous circuit. These graphical specifications can be difficult to describe compositionally,
and provide little reusability of useful sections of a graph. In this thesis
we present Asynchronous Concepts, a new design methodology for asynchronous circuit
design. A concept is a self-contained description of a circuit requirement, which is
composable with any other concept, allowing compositional specification of large asynchronous
circuits. Concepts can be shared, reused and extended by users, promoting the
reuse of behaviours within single or multiple specifications. Asynchronous Concepts can
be translated to STGs to benefit from the existing theory and tools developed by the
asynchronous circuits community.
Plato is a software tool developed for Asynchronous Concepts that supports the
presented design methodology, and provides automated methods for translation to STGs.
The design flow which utilises Asynchronous Concepts is automated using Plato and
the open-source toolsuite Workcraft, which can use the translated STGs in verification
and synthesis using integrated tools. The proposed language, the design flow, and the
supporting tools are evaluated on real-world case studies
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Compiling Irregular Software to Specialized Hardware
High-level synthesis (HLS) has simplified the design process for energy-efficient hardware accelerators: a designer specifies an accelerator’s behavior in a “high-level” language, and a toolchain synthesizes register-transfer level (RTL) code from this specification. Many HLS systems produce efficient hardware designs for regular algorithms (i.e., those with limited conditionals or regular memory access patterns), but most struggle with irregular algorithms that rely on dynamic, data-dependent memory access patterns (e.g., traversing pointer-based structures like lists, trees, or graphs). HLS tools typically provide imperative, side-effectful languages to the designer, which makes it difficult to correctly specify and optimize complex, memory-bound applications.
In this dissertation, I present an alternative HLS methodology that leverages properties of functional languages to synthesize hardware for irregular algorithms. The main contribution is an optimizing compiler that translates pure functional programs into modular, parallel dataflow networks in hardware. I give an overview of this compiler, explain how its source and target together enable parallelism in the face of irregularity, and present two specific optimizations that further exploit this parallelism. Taken together, this dissertation verifies my thesis that pure functional programs exhibiting irregular memory access patterns can be compiled into specialized hardware and optimized for parallelism.
This work extends the scope of modern HLS toolchains. By relying on properties of pure functional languages, our compiler can synthesize hardware from programs containing constructs that commercial HLS tools prohibit, e.g., recursive functions and dynamic memory allocation. Hardware designers may thus use our compiler in conjunction with existing HLS systems to accelerate a wider class of algorithms than before
Analysis Techniques for Concurrent Programming Languages
Los lenguajes concurrentes est an cada d a m as presentes en nuestra sociedad,
tanto en las nuevas tecnolog as como en los sistemas utilizados de manera cotidiana. M as a un, dada la actual distribuci on de los sistemas y su arquitectura interna,
cabe esperar que este hecho siga siendo una realidad en los pr oximos a~nos. En
este contexto, el desarrollo de herramientas de apoyo al desarrollo de programas
concurrentes se vuelve esencial. Adem as, el comportamiento de los sistemas concurrentes es especialmente dif cil de analizar, por lo que cualquier herramienta que
ayude en esta tarea, a un cuando sea limitada, ser a de gran utilidad. Por ejemplo, podemos encontrar herramientas para la depuraci on, an alisis, comprobaci on,
optimizaci on, o simpli caci on de programas. Muchas de ellas son ampliamente
utilizadas por los programadores hoy en d a.
El prop osito de esta tesis es introducir, a trav es de diferentes lenguajes de
programaci on concurrentes, t ecnicas de an alisis que puedan ayudar a mejorar la
experiencia del desarrollo y publicaci on de software para modelos concurrentes.
En esta tesis se introducen tanto an alisis est aticos (aproximando todas las posibles ejecuciones) como din amicos (considerando una ejecuci on en concreto). Los
trabajos aqu propuestos di eren lo su ciente entre s para constituir ideas totalmente independientes, pero manteniendo un nexo com un: el hecho de ser un
an alisis para un lenguaje concurrente. Todos los an alisis presentados han sido
de nidos formalmente y se ha probado su correcci on, asegurando que los resultados obtenidos tendr an el grado de abilidad necesario en sistemas que lo requieran,
como por ejemplo, en sistemas cr ticos. Adem as, se incluye la descripci on de las
herramientas software que implementan las diferentes ideas propuestas. Esto le da
al trabajo una utilidad m as all a del marco te orico, permitiendo poner en pr actica
y probar con ejemplos reales los diferentes an alisis.
Todas las ideas aqu presentadas constituyen, por s mismas, propuestas aplicables en multitud de contextos y problemas actuales. Adem as, individualmente sirven de punto de partida para otros an alisis derivados, as como para la adaptaci on
a otros lenguajes de la misma familia. Esto le da un valor a~nadido a este trabajo,
como bien atestiguan algunos trabajos posteriores que ya se est an bene ciando de
los resultados obtenidos en esta tesis.Concurrent languages are increasingly present in our society, both in new
technologies and in the systems used on a daily basis. Moreover, given the
current systems distribution and their internal architecture, one can expect
that this remains so in the coming years. In this context, the development of
tools to support the implementation of concurrent programs becomes essential.
Futhermore, the behavior of concurrent systems is particularly difficult
to analyse, so that any tool that helps in this task, even if in a limited way,
will be very useful. For example, one can find tools for debugging, analysis,
testing, optimisation, or simplification of programs, which are widely used
by programmers nowadays.
The purpose of this thesis is to introduce, through various concurrent programming
languages, some analysis techniques that can help to improve the
experience of the software development and release for concurrent models.
This thesis introduces both static (approximating all possible executions) and
dynamic (considering a specific execution) analysis. The topics considered
here differ enough from each other to be fully independent. Nevertheless,
they have a common link: they can be used to analyse properties of a concurrent
programming language. All the analyses presented here have been
formally defined and their correctness have been proved, ensuring that the
results will have the reliability degree which is needed for some systems (for
instance, for critical systems). It also includes a description of the software
tools that implement the different ideas proposed. This gives the work a usefulness
well beyond the theoretical aspect, allowing us to put it in practice
and to test the different analyses with real-world examples All the ideas here presented are, by themselves, approaches that can be applied
in many current contexts and problems. Moreover, individually they
serve as a starting point for other derived analysis, as well as for the adaptation
to other languages of the same family. This gives an added value to
this work, a fact confirmed by some later works that are already benefiting
from the results obtained in this thesis.Tamarit Muñoz, S. (2013). Analysis Techniques for Concurrent Programming Languages [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31651TESI
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