182 research outputs found

    Low‐latency Java communication devices on RDMA‐enabled networks

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    This is the peer reviewed version of the following article: Expósito, R. R., Taboada, G. L., Ramos, S., Touriño, J., & Doallo, R. (2015). Low‐latency Java communication devices on RDMA‐enabled networks. Concurrency and Computation: Practice and Experience, 27(17), 4852-4879., which has been published in final form at https://doi.org/10.1002/cpe.3473. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.[Abstract] Providing high‐performance inter‐node communication is a key capability for running high performance computing applications efficiently on parallel architectures. In fact, current systems deployments are aggregating a significant number of cores interconnected via advanced networking hardware with Remote Direct Memory Access (RDMA) mechanisms, that enable zero‐copy and kernel‐bypass features. The use of Java for parallel programming is becoming more promising thanks to some useful characteristics of this language, particularly its built‐in multithreading support, portability, easy‐to‐learn properties, and high productivity, along with the continuous increase in the performance of the Java virtual machine. However, current parallel Java applications generally suffer from inefficient communication middleware, mainly based on protocols with high communication overhead that do not take full advantage of RDMA‐enabled networks. This paper presents efficient low‐level Java communication devices that overcome these constraints by fully exploiting the underlying RDMA hardware, providing low‐latency and high‐bandwidth communications for parallel Java applications. The performance evaluation conducted on representative RDMA networks and parallel systems has shown significant point‐to‐point performance increases compared with previous Java communication middleware, allowing to obtain up to 40% improvement in application‐level performance on 4096 cores of a Cray XE6 supercomputer.Ministerio de Economía y Competitividad; TIN2013-42148-PXunta de Galicia; GRC2013/055Ministerio de Educación y Ciencia; AP2010-434

    Analyzing the impact of supporting out-of-order communication on in-order performance with iWARP

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    Towards the Teraflop CFD

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    We are surveying current projects in the area of parallel supercomputers. The machines considered here will become commercially available in the 1990 - 1992 time frame. All are suitable for exploring the critical issues in applying parallel processors to large scale scientific computations, in particular CFD calculations. This chapter presents an overview of the surveyed machines, and a detailed analysis of the various architectural and technology approaches taken. Particular emphasis is placed on the feasibility of a Teraflops capability following the paths proposed by various developers

    RDMA mechanisms for columnar data in analytical environments

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    Dissertação de mestrado integrado em Engenharia InformáticaThe amount of data in information systems is growing constantly and, as a consequence, the complexity of analytical processing is greater. There are several storage solutions to persist this information, with different architectures targeting different use cases. For analytical processing, storage solutions with a column-oriented format are particularly relevant due to the convenient placement of the data in persistent storage and the closer mapping to in-memory processing. The access to the database is typically remote and has overhead associated, mainly when it is necessary to obtain the same data multiple times. Thus, it is desirable to have a cache on the processing side and there are solutions for this. The problem with the existing so lutions is the overhead introduced by network latency and memory-copy between logical layers. Remote Direct Memory Access (RDMA) mechanisms have the potential to help min imize this overhead. Furthermore, this type of mechanism is indicated for large amounts of data because zero-copy has more impact as the data volume increases. One of the problems associated with RDMA mechanisms is the complexity of development. This complexity is induced by its different development paradigm when compared to other network commu nication protocols, for example, TCP. Aiming to improve the efficiency of analytical processing, this dissertation presents a dis tributed cache that takes advantage of RDMA mechanisms to improve analytical processing performance. The cache abstracts the intricacies of RDMA mechanisms and is developed as a middleware making it transparent to take advantage of this technology. Moreover, this technique could be used in other contexts where a distributed cache makes sense, such as a set of replicated web servers that access the same database.A quantidade de informação nos sistemas informáticos tem vindo a aumentar e consequentemente, a complexidade do processamento analítico torna-se maior. Existem diversas soluções para o armazenamento de dados com diferentes arquiteturas e indicadas para determinados casos de uso. Num contexto de processamento analítico, uma solução com o modelo de dados colunar e especialmente relevante devido à disposição conveniente dos dados em disco e a sua proximidade com o mapeamento em memória desses mesmos dados. Muitas vezes, o acesso aos dados é feito remotamente e isso traz algum overhead, principalmente quando é necessário aceder aos mesmos dados mais do que uma vez. Posto isto, é vantajoso fazer caching dos dados e já existem soluções para esse efeito. O overhead introduzido pela latência da rede e cópia de buffers entre camadas lógicas é o principal problema das soluções existentes. Os mecanismos de acesso direto à memória remota (RDMA - Remote Direct Memory Access) tem o potencial de melhorar o desempenho neste cenário. Para além disso, este tipo de tecnologia faz sentido em sistemas com grandes quantidades de dados, nos quais o acesso direto pode ter um impacto ainda maior por ser zero-copy. Um dos problemas associados com mecanismos RDMA é a complexidade de desenvolvimento. Esta complexidade é causada pelo paradigma de desenvolvimento completamente diferente de outros protocolos de comunicação, como por exemplo, TCP. Tendo em vista melhorar a eficiência do processamento analítico, esta dissertação propõe uma solução de cache distribuída que tira partido de mecanismos de acesso direto a memoria remota (RDMA). A cache abstrai as particularidades dos mecanismos RDMA e é disponibilizada como middleware, tornando a utilização desta tecnologia completamente transparente. Esta solução visa os sistemas de processamento analítico, mas poderá ser utilizada noutros contextos em que uma cache distribuída faça sentido, como por exemplo num conjunto de servidores web replicados que acedem a mesma base de dados

    High Performance Computing using Infiniband-based clusters

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    A parallel implementation of a multisensor feature-based range-estimation method

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    There are many proposed vision based methods to perform obstacle detection and avoidance for autonomous or semi-autonomous vehicles. All methods, however, will require very high processing rates to achieve real time performance. A system capable of supporting autonomous helicopter navigation will need to extract obstacle information from imagery at rates varying from ten frames per second to thirty or more frames per second depending on the vehicle speed. Such a system will need to sustain billions of operations per second. To reach such high processing rates using current technology, a parallel implementation of the obstacle detection/ranging method is required. This paper describes an efficient and flexible parallel implementation of a multisensor feature-based range-estimation algorithm, targeted for helicopter flight, realized on both a distributed-memory and shared-memory parallel computer
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