Automatic parallelization for embedded multi-core systems using high level cost models

Nowadays, embedded and cyber-physical systems are utilized in nearly all operational areas in order to support and enrich peoples' everyday life. To cope with the demands imposed by modern embedded systems, the employment of MPSoC devices is often the most profitable solution. However, many embedded applications are still written in a sequential way. In order to benefit from the multiple cores available on those devices, the application code has to be divided into concurrently executed tasks. Since performing this partitioning manually is an error-prone and also time-consuming job, many automatic parallelization approaches were developed in the past. Most of these existing approaches were developed in the context of high-performance and desktop computers so that their applicability to embedded devices is limited. Many new challenges arise if applications should be ported to embedded MPSoCs in an efficient way. Therefore, novel parallelization techniques were developed in the context of this thesis that are tailored towards special requirements demanded by embedded multi-core devices. All approaches presented in this thesis are based on sophisticated parallelization techniques employing high-level cost models to estimate the benefit of parallel execution. This enables the creation of well-balanced tasks, which is essential if applications should be parallelized efficiently. In addition, several other requirements of embedded devices are covered, like the consideration of multiple objectives simultaneously. As a result, beneficial trade-offs between several objectives, like, e.g., energy consumption and execution time can be found enabling the extraction of solutions which are highly optimized for a specific application scenario. To be applicable to many embedded application domains, approaches extracting different kinds of parallelism were also developed. The structure of the global parallelization approach facilitates the combination of different approaches in a plug-and-play fashion. Thus, the advantages of multiple parallelization techniques can easily be combined. Finally, in addition to parallelization approaches for homogeneous MPSoCs, optimized ones for heterogeneous devices were also developed in this thesis since the trend towards heterogeneous multi-core architectures is inexorable. To the best of the author's knowledge, most of these objectives and especially their combination were not covered by existing parallelization frameworks, so far. By combining all of them, a parallelization framework that is well optimized for embedded multi-core devices was developed in the context of this thesis

Programming MPSoC platforms: Road works ahead

This paper summarizes a special session on multicore/multi-processor system-on-chip (MPSoC) programming challenges. The current trend towards MPSoC platforms in most computing domains does not only mean a radical change in computer architecture. Even more important from a SW developer´s viewpoint, at the same time the classical sequential von Neumann programming model needs to be overcome. Efficient utilization of the MPSoC HW resources demands for radically new models and corresponding SW development tools, capable of exploiting the available parallelism and guaranteeing bug-free parallel SW. While several standards are established in the high-performance computing domain (e.g. OpenMP), it is clear that more innovations are required for successful\ud deployment of heterogeneous embedded MPSoC. On the other hand, at least for coming years, the freedom for disruptive programming technologies is limited by the huge amount of certified sequential code that demands for a more pragmatic, gradual tool and code replacement strategy

Tackling Exascale Software Challenges in Molecular Dynamics Simulations with GROMACS

GROMACS is a widely used package for biomolecular simulation, and over the last two decades it has evolved from small-scale efficiency to advanced heterogeneous acceleration and multi-level parallelism targeting some of the largest supercomputers in the world. Here, we describe some of the ways we have been able to realize this through the use of parallelization on all levels, combined with a constant focus on absolute performance. Release 4.6 of GROMACS uses SIMD acceleration on a wide range of architectures, GPU offloading acceleration, and both OpenMP and MPI parallelism within and between nodes, respectively. The recent work on acceleration made it necessary to revisit the fundamental algorithms of molecular simulation, including the concept of neighborsearching, and we discuss the present and future challenges we see for exascale simulation - in particular a very fine-grained task parallelism. We also discuss the software management, code peer review and continuous integration testing required for a project of this complexity.Comment: EASC 2014 conference proceedin

An overview of the ciao multiparadigm language and program development environment and its design philosophy

We describe some of the novel aspects and motivations behind the design and implementation of the Ciao multiparadigm programming system. An important aspect of Ciao is that it provides the programmer with a large number of useful features from different programming paradigms and styles, and that the use of each of these features can be turned on and off at will for each program module. Thus, a given module may be using e.g. higher order functions and constraints, while another module may be using objects, predicates, and concurrency. Furthermore, the language is designed to be extensible in a simple and modular way. Another important aspect of Ciao is its programming environment, which provides a powerful preprocessor (with an associated assertion language) capable of statically finding non-trivial bugs, verifying that programs comply with specifications, and performing many types of program optimizations. Such optimizations produce code that is highly competitive with other dynamic languages or, when the highest levéis of optimization are used, even that of static languages, all while retaining the interactive development environment of a dynamic language. The environment also includes a powerful auto-documenter. The paper provides an informal overview of the language and program development environment. It aims at illustrating the design philosophy rather than at being exhaustive, which would be impossible in the format of a paper, pointing instead to the existing literature on the system