MPSoCBench : um framework para avaliação de ferramentas e metodologias para sistemas multiprocessados em chip

Orientador: Rodolfo Jardim de AzevedoTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Recentes metodologias e ferramentas de projetos de sistemas multiprocessados em chip (MPSoC) aumentam a produtividade por meio da utilização de plataformas baseadas em simuladores, antes de definir os últimos detalhes da arquitetura. No entanto, a simulação só é eficiente quando utiliza ferramentas de modelagem que suportem a descrição do comportamento do sistema em um elevado nível de abstração. A escassez de plataformas virtuais de MPSoCs que integrem hardware e software escaláveis nos motivou a desenvolver o MPSoCBench, que consiste de um conjunto escalável de MPSoCs incluindo quatro modelos de processadores (PowerPC, MIPS, SPARC e ARM), organizado em plataformas com 1, 2, 4, 8, 16, 32 e 64 núcleos, cross-compiladores, IPs, interconexões, 17 aplicações paralelas e estimativa de consumo de energia para os principais componentes (processadores, roteadores, memória principal e caches). Uma importante demanda em projetos MPSoC é atender às restrições de consumo de energia o mais cedo possível. Considerando que o desempenho do processador está diretamente relacionado ao consumo, há um crescente interesse em explorar o trade-off entre consumo de energia e desempenho, tendo em conta o domínio da aplicação alvo. Técnicas de escalabilidade dinâmica de freqüência e voltagem fundamentam-se em gerenciar o nível de tensão e frequência da CPU, permitindo que o sistema alcance apenas o desempenho suficiente para processar a carga de trabalho, reduzindo, consequentemente, o consumo de energia. Para explorar a eficiência energética e desempenho, foram adicionados recursos ao MPSoCBench, visando explorar escalabilidade dinâmica de voltaegem e frequência (DVFS) e foram validados três mecanismos com base na estimativa dinâmica de energia e taxa de uso de CPUAbstract: Recent design methodologies and tools aim at enhancing the design productivity by providing a software development platform before the definition of the final Multiprocessor System on Chip (MPSoC) architecture details. However, simulation can only be efficiently performed when using a modeling and simulation engine that supports system behavior description at a high abstraction level. The lack of MPSoC virtual platform prototyping integrating both scalable hardware and software in order to create and evaluate new methodologies and tools motivated us to develop the MPSoCBench, a scalable set of MPSoCs including four different ISAs (PowerPC, MIPS, SPARC, and ARM) organized in platforms with 1, 2, 4, 8, 16, 32, and 64 cores, cross-compilers, IPs, interconnections, 17 parallel version of software from well-known benchmarks, and power consumption estimation for main components (processors, routers, memory, and caches). An important demand in MPSoC designs is the addressing of energy consumption constraints as early as possible. Whereas processor performance comes with a high power cost, there is an increasing interest in exploring the trade-off between power and performance, taking into account the target application domain. Dynamic Voltage and Frequency Scaling techniques adaptively scale the voltage and frequency levels of the CPU allowing it to reach just enough performance to process the system workload while meeting throughput constraints, and thereby, reducing the energy consumption. To explore this wide design space for energy efficiency and performance, both for hardware and software components, we provided MPSoCBench features to explore dynamic voltage and frequency scalability (DVFS) and evaluated three mechanisms based on energy estimation and CPU usage rateDoutoradoCiência da ComputaçãoDoutora em Ciência da Computaçã

Comparative performance evaluation of latency and link dynamic power consumption modelling algorithms in wormhole switching networks on chip

The simulation of interconnect architectures can be a time-consuming part of the design flow of on-chip multiprocessors. Accurate simulation of state-of-the art network-on-chip interconnects can take several hours for realistic application examples, and this process must be repeated for each design iteration because the interactions between design choices can greatly affect the overall throughput and latency performance of the system. This paper presents a series of network-on-chip transaction-level model (TLM) algorithms that provide a highly abstracted view of the process of data transmission in priority preemptive and non-preemptive networks-on-chip, which permit a major reduction in simulation event count. These simulation models are tested using two realistic application case studies and with synthetic traffic. Results presented demonstrate that these lightweight TLM simulation models can produce latency figures accurate to within mere flits for the majority of flows, and more than 93% accurate link dynamic power consumption modelling, while simulating 2.5 to 3 orders of magnitude faster when compared to a cycle-accurate model of the same interconnect

Fast simulation of networks-on-chip with priority-preemptive arbitration

An increasingly time-consuming part of the design flow of on-chip multiprocessors is the simulation of the interconnect architecture. The accurate simulation of state-of-the art network-on-chip interconnects can take hours, and this process is repeated for each design iteration because it provides valuable insights on communication latencies that can greatly affect the overall performance of the system. In this article, we identify a time-predictable network-on-chip architecture and show that its timing behaviour can be predicted using models which are far less complex than the architecture itself. We then explore such a feature to produce simplified and lightweight simulation models that can produce latency figures with more than 90% accuracy and simulate more than 1,000 times faster when compared to a cycle-accurate model of the same interconnect