High Performance Computing using Infiniband-based clusters

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Building a Framework for High-performance In-memory Message-Oriented Middleware

Message-Oriented Middleware (MOM) is a popular class of software used in many distributed applications, ranging from business systems and social networks to gaming and streaming media services. As workloads continue to grow both in terms of the number of users and the amount of content, modern MOM systems face increasing demands in terms of performance and scalability. Recent advances in networking such as Remote Direct Memory Access (RDMA) offer a more efficient data transfer mechanism compared to traditional kernel-level socket networking used by existing widely-used MOM systems. Unfortunately, RDMA’s complex interface has made it difficult for MOM systems to utilize its capabilities. In this thesis, we introduce a framework called RocketBufs, which provides abstractions and interfaces for constructing high-performance MOM systems. Applications implemented using RocketBufs produce and consume data using regions of memory called buffers while the framework is responsible for transmitting, receiving and synchronizing buffer access. RocketBufs’ buffer abstraction is designed to work efficiently with different transport protocols, allowing messages to be distributed using RDMA or TCP using the same APIs (i.e., by simply changing a configuration file). We demonstrate the utility and evaluate the performance of RocketBufs by using it to implement a publish/subscribe system called RBMQ. We compare it against two widely-used, industry-grade MOM systems, namely RabbitMQ and Redis. Our evaluations show that when using TCP, RBMQ achieves up to 1.9 times higher messaging throughput than RabbitMQ, a message queuing system with an equivalent flow control scheme. When RDMA is used, RBMQ shows significant gains in messaging throughput (up to 3.7 times higher than RabbitMQ and up to 1.7 times higher than Redis), as well as reductions in median delivery latency (up to 81% lower than RabbitMQ and 47% lower than Redis). In addition, on RBMQ subscriber hosts configured to use RDMA, data transfers occur with negligible CPU overhead regardless of the amount of data being transferred. This allows CPU resources to be used for other purposes like processing data. To further demonstrate the flexibility of RocketBufs, we use it to build a live streaming video application by integrating RocketBufs into a web server to receive disseminated video data. When compared with the same application built with Redis, the RocketBufs-based dissemination host achieves live streaming throughput up to 73% higher while disseminating data, and the RocketBufs-based web server shows a reduction of up to 95% in CPU utilization, allowing for up to 55% more concurrent viewers to be serviced

A protocol reconfiguration and optimization system for MPI

Modern high performance computing (HPC) applications, for example adaptive mesh refinement and multi-physics codes, have dynamic communication characteristics which result in poor performance on current Message Passing Interface (MPI) implementations. The degraded application performance can be attributed to a mismatch between changing application requirements and static communication library functionality. To improve the performance of these applications, MPI libraries should change their protocol functionality in response to changing application requirements, and tailor their functionality to take advantage of hardware capabilities. This dissertation describes Protocol Reconfiguration and Optimization system for MPI (PRO-MPI), a framework for constructing profile-driven reconfigurable MPI libraries; these libraries use past application characteristics (profiles) to dynamically change their functionality to match the changing application requirements. The framework addresses the challenges of designing and implementing the reconfigurable MPI libraries, which include collecting and reasoning about application characteristics to drive the protocol reconfiguration and defining abstractions required for implementing these reconfigurations. Two prototype reconfigurable MPI implementations based on the framework - Open PRO-MPI and Cactus PRO-MPI - are also presented to demonstrate the utility of the framework. To demonstrate the effectiveness of reconfigurable MPI libraries, this dissertation presents experimental results to show the impact of using these libraries on the application performance. The results show that PRO-MPI improves the performance of important HPC applications and benchmarks. They also show that HyperCLaw performance improves by approximately 22% when exact profiles are available, and HyperCLaw performance improves by approximately 18% when only approximate profiles are available

RDMA mechanisms for columnar data in analytical environments

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

Implementation and comparison of iSCSI over RDMA

iSCSI is an emerging storage network technology that allows for block-level access to disk drives over a computer network. Since iSCSI runs over the very ubiquitous TCP/IP protocol it has many advantages over its more proprietary alternatives. Due to the recent movement toward 10 gigabit Ethernet, storage vendors are interested to see how this large increase in network bandwidth could benefit the iSCSI protocol. In order to make full use of the bandwidth provided by a 10 gigabit Ethernet link, specialized Remote Direct Memory Access hardware is being developed to offload processing and reduce the data-copy-overhead found in a standard TCP/IP network stack. This thesis focuses on the development of an iSCSI implementation that is capable of supporting this new hardware and the evaluation of its performance. This thesis depicts the approach used to implement the iSCSI Extensions for Remote Direct Memory Access (iSER) with the UNH iSCSI reference implementation. This approach involves a three step process: moving UNH-iSCSI from the Linux kernel to the Linux user-space, adding support for the iSER extensions to our user-space iSCSI and finally moving everything back into the Linux kernel. In addition to a description of the implementation, results are given that demonstrate the performance of the completed iSER-assisted iSCSI implementation