5,697 research outputs found

    Improving Memory Hierarchy Utilisation for Stencil Computations on Multicore Machines

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    Although modern supercomputers are composed of multicore machines, one can find scientists that still execute their legacy applications which were developed to monocore cluster where memory hierarchy is dedicated to a sole core. The main objective of this paper is to propose and evaluate an algorithm that identify an efficient blocksize to be applied on MPI stencil computations on multicore machines. Under the light of an extensive experimental analysis, this work shows the benefits of identifying blocksizes that will dividing data on the various cores and suggest a methodology that explore the memory hierarchy available in modern machines

    Autonomic State Management for Optimistic Simulation Platforms

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    We present the design and implementation of an autonomic state manager (ASM) tailored for integration within optimistic parallel discrete event simulation (PDES) environments based on the C programming language and the executable and linkable format (ELF), and developed for execution on x8664 architectures. With ASM, the state of any logical process (LP), namely the individual (concurrent) simulation unit being part of the simulation model, is allowed to be scattered on dynamically allocated memory chunks managed via standard API (e.g., malloc/free). Also, the application programmer is not required to provide any serialization/deserialization module in order to take a checkpoint of the LP state, or to restore it in case a causality error occurs during the optimistic run, or to provide indications on which portions of the state are updated by event processing, so to allow incremental checkpointing. All these tasks are handled by ASM in a fully transparent manner via (A) runtime identification (with chunk-level granularity) of the memory map associated with the LP state, and (B) runtime tracking of the memory updates occurring within chunks belonging to the dynamic memory map. The co-existence of the incremental and non-incremental log/restore modes is achieved via dual versions of the same application code, transparently generated by ASM via compile/link time facilities. Also, the dynamic selection of the best suited log/restore mode is actuated by ASM on the basis of an innovative modeling/optimization approach which takes into account stability of each operating mode with respect to variations of the model/environmental execution parameters

    Towards Lattice Quantum Chromodynamics on FPGA devices

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    In this paper we describe a single-node, double precision Field Programmable Gate Array (FPGA) implementation of the Conjugate Gradient algorithm in the context of Lattice Quantum Chromodynamics. As a benchmark of our proposal we invert numerically the Dirac-Wilson operator on a 4-dimensional grid on three Xilinx hardware solutions: Zynq Ultrascale+ evaluation board, the Alveo U250 accelerator and the largest device available on the market, the VU13P device. In our implementation we separate software/hardware parts in such a way that the entire multiplication by the Dirac operator is performed in hardware, and the rest of the algorithm runs on the host. We find out that the FPGA implementation can offer a performance comparable with that obtained using current CPU or Intel's many core Xeon Phi accelerators. A possible multiple node FPGA-based system is discussed and we argue that power-efficient High Performance Computing (HPC) systems can be implemented using FPGA devices only.Comment: 17 pages, 4 figure

    VIRTUALIZED BASEBAND UNITS CONSOLIDATION IN ADVANCED LTE NETWORKS USING MOBILITY- AND POWER-AWARE ALGORITHMS

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    Virtualization of baseband units in Advanced Long-Term Evolution networks and a rapid performance growth of general purpose processors naturally raise the interest in resource multiplexing. The concept of resource sharing and management between virtualized instances is not new and extensively used in data centers. We adopt some of the resource management techniques to organize virtualized baseband units on a pool of hosts and investigate the behavior of the system in order to identify features which are particularly relevant to mobile environment. Subsequently, we introduce our own resource management algorithm specifically targeted to address some of the peculiarities identified by experimental results

    On the co-design of scientific applications and long vector architectures

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    The landscape of High Performance Computing (HPC) system architectures keeps expanding with new technologies and increased complexity. To improve the efficiency of next-generation compute devices, architects are looking for solutions beyond the commodity CPU approach. In 2021, the five most powerful supercomputers in the world use either GP-GPU (General-purpose computing on graphics processing units) accelerators or a customized CPU specially designed to target HPC applications. This trend is only expected to grow in the next years motivated by the compute demands of science and industry. As architectures evolve, the ecosystem of tools and applications must follow. The choices in the number of cores in a socket, the floating point-units per core and the bandwidth through the memory hierarchy among others, have a large impact in the power consumption and compute capabilities of the devices. To balance CPU and accelerators, designers require accurate tools for analyzing and predicting the impact of new architectural features on the performance of complex scientific applications at scale. In such a large design space, capturing and modeling with simulators the complex interactions between the system software and hardware components is a defying challenge. Moreover, applications must be able to exploit those designs with aggressive compute capabilities and memory bandwidth configurations. Algorithms and data structures will need to be redesigned accordingly to expose a high degree of data-level parallelism allowing them to scale in large systems. Therefore, next-generation computing devices will be the result of a co-design effort in hardware and applications supported by advanced simulation tools. In this thesis, we focus our work on the co-design of scientific applications and long vector architectures. We significantly extend a multi-scale simulation toolchain enabling accurate performance and power estimations of large-scale HPC systems. Through simulation, we explore the large design space in current HPC trends over a wide range of applications. We extract speedup and energy consumption figures analyzing the trade-offs and optimal configurations for each of the applications. We describe in detail the optimization process of two challenging applications on real vector accelerators, achieving outstanding operation performance and full memory bandwidth utilization. Overall, we provide evidence-based architectural and programming recommendations that will serve as hardware and software co-design guidelines for the next generation of specialized compute devices.El panorama de las arquitecturas de los sistemas para la Computación de Alto Rendimiento (HPC, de sus siglas en inglés) sigue expandiéndose con nuevas tecnologías y complejidad adicional. Para mejorar la eficiencia de la próxima generación de dispositivos de computación, los arquitectos están buscando soluciones más allá de las CPUs. En 2021, los cinco supercomputadores más potentes del mundo utilizan aceleradores gráficos aplicados a propósito general (GP-GPU, de sus siglas en inglés) o CPUs diseñadas especialmente para aplicaciones HPC. En los próximos años, se espera que esta tendencia siga creciendo motivada por las demandas de más potencia de computación de la ciencia y la industria. A medida que las arquitecturas evolucionan, el ecosistema de herramientas y aplicaciones les debe seguir. Las decisiones eligiendo el número de núcleos por zócalo, las unidades de coma flotante por núcleo y el ancho de banda a través de la jerarquía de memoría entre otros, tienen un gran impacto en el consumo de energía y las capacidades de cómputo de los dispositivos. Para equilibrar las CPUs y los aceleradores, los diseñadores deben utilizar herramientas precisas para analizar y predecir el impacto de nuevas características de la arquitectura en el rendimiento de complejas aplicaciones científicas a gran escala. Dado semejante espacio de diseño, capturar y modelar con simuladores las complejas interacciones entre el software de sistema y los componentes de hardware es un reto desafiante. Además, las aplicaciones deben ser capaces de explotar tales diseños con agresivas capacidades de cómputo y ancho de banda de memoria. Los algoritmos y estructuras de datos deberán ser rediseñadas para exponer un alto grado de paralelismo de datos permitiendo así escalarlos en grandes sistemas. Por lo tanto, la siguiente generación de dispósitivos de cálculo será el resultado de un esfuerzo de codiseño tanto en hardware como en aplicaciones y soportado por avanzadas herramientas de simulación. En esta tesis, centramos nuestro trabajo en el codiseño de aplicaciones científicas y arquitecturas vectoriales largas. Extendemos significativamente una serie de herramientas para la simulación multiescala permitiendo así obtener estimaciones de rendimiento y potencia de sistemas HPC de gran escala. A través de simulaciones, exploramos el gran espacio de diseño de las tendencias actuales en HPC sobre un amplio rango de aplicaciones. Extraemos datos sobre la mejora y el consumo energético analizando las contrapartidas y las configuraciones óptimas para cada una de las aplicaciones. Describimos en detalle el proceso de optimización de dos aplicaciones en aceleradores vectoriales, obteniendo un rendimiento extraordinario a nivel de operaciones y completa utilización del ancho de memoria disponible. Con todo, ofrecemos recomendaciones empíricas a nivel de arquitectura y programación que servirán como instrucciones para diseñar mejor hardware y software para la siguiente generación de dispositivos de cálculo especializados.Postprint (published version

    The Design of a System Architecture for Mobile Multimedia Computers

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    This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies
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